Corn (Zea mays L.) is one of the major crops in world agriculture with versatile applications. Approximately 20% of corn grain is used for food purposes, 15-20% for technical purposes, and about two-thirds for feed purposes.
In the United States, Canada, and Australia, the crop is commonly referred to as “corn.” “Corn” has been a common term for grain or cereal, such as wheat in England and oats in Ireland and Scotland. It is not surprising, therefore, that the name “corn” was applied to the new kinds of grain that settlers discovered in the Americas. Nevertheless, most of the world’s population recognizes Zea mays as “maize. Corn’s relatively wide adaptability to growth allows it to be grown in most parts of the globe. Only wheat and rice are ahead of corn in terms of production.
Contents
- Economic importance
- History of crop
- Cultivation areas and yields
- Botanical description
- Subspecies
- Biological features
- Vegetation
- Crop rotation
- Fertilizer system
- Tillage system
- Seeding
- Crop care
- Diseases
- Pests
- Harvesting
- Specifics of cultivation under irrigation
- Modern corn cultivation technologies
- The use of hybrid seeds and methods of their cultivation
- Sources
Economic importance
Corn kernels contain 65-70% carbohydrates, 9-12% protein, 4-8% fat, 1.5% mineral salts, 2.5% fiber, vitamins, and 14-15% water. Grains are used for making flour, groats, flakes, preserves (sugar corn), starch, ethyl alcohol, dextrin, beer, glucose, sugar, molasses, syrups, honey, corn oil (the germ of the grain contains up to 30% fat), vitamin E, ascorbic and glutamic acids. Unripe cobs are eaten raw, boiled, and canned. Pistillate stalks are used in medicine. The stems, leaves, and cobs can be used to make paper, linoleum, viscose, activated carbon, artificial cork, plastics, and anesthetics.
Corn flour contains little gluten, so it is not suitable for baking, it is added to bakery and confectionery products. Corn oil is semi-dry, with an iodine number of 111-133.
Corn grain serves as a fodder for farm animals. 1 kg of corn equals 1.34 fodder unit, contains 78 g of digestible protein. Valuable component of compound feeds. Corn grain protein contains few essential amino acids – lysine and tryptophan, it is rich in low-value forage protein – zeine.
In Russia corn is the main silage crop. For this purpose cobs in a phase of milky-wax or wax maturity separately or together with leaves and stalks are used. Dry stems mixed with succulent crops such as forage gourds, pumpkins, and beet tops can be used for silage. Silage has good digestibility and dietary properties. 100 kg of silage made from corn in the lactiferous maturity phase contains 21-28 fodder units and up to 1.8 kg of digestible protein. To increase the protein content of the silage, leguminous grasses or fodder beans are added to it in mixed compacted crops.
Corn can be used for carotene-rich green fodder. Dry leaves, stems and cob cores left after harvesting for grain can also be used for fodder, sometimes mixed with succulent fodder. 100 kilos of maize straw equals 37 feed units, while 100 kilos of shredded cob stalks equals 35 feed units. Green leaves and stems are also used as fodder.
As a row crop, corn is a good preceding crop in the crop rotation. Its sowing promotes clearing of fields from weeds, almost has no pests and pathogens common with grain crops. After corn a large amount of crop residues remains. Corn is a good preceding crop for grain harvesting, and it is a vaporizer crop for green fodder. It is widespread in cuttings, in stubble and repeated crops. It is also used as a sward, and in the Central Black Earth Zone and the Northern Caucasus as a vaporizer for green fodder and silage.
When corn is cultivated for grain, pumpkin and beans are planted in between the rows as compaction crops.
History of crop
Corn is the oldest cultivated plant. It comes from Central and South America, the tropics and subtropics, as indicated by archaeological finds of pollen, panicles, grains and cobs of primitive forms of corn and the results of genetic and cytoembryological studies. It was introduced into culture about 5,000 years B.C. In the pre-Columbian era, it was one of the principal food crops of the aborigines of these areas.
The origin of the corn species Zea mays L. has not yet been deciphered by phylogenetic systematics at this time. In Mexico, new species of the tribe Maydeae belonging to theo-synths, the maize species Zea perennis and Z. diploperennis.
Columbus reported the discovery of the new plant shortly after his discovery of America. The first specimens came to Europe at the end of the 15th century. Originally corn was cultivated as an ornamental plant. Later in France, Italy, and Portugal it was recognized as a food, then as a fodder crop. In the 16th century corn quickly spread in areas with favorable conditions for its cultivation: in Northern Africa, India, and China. In Russia it became known in the XII century and spread rapidly in the steppe zone. In the second half of the 19th century attempts were made to cultivate it in Moscow, Smolensk, and some other provinces, but it was not successful.
At the moment corn is a highly cultivated plant, incapable of growing without human help, because the grain almost never shatters, the cobs are rarely broken and the stalk is sufficiently strong.
Cultivation areas and yields
Corn is widely used around the world because of its high nutritional quality and good productivity and ability to adapt to growing conditions. The areas of cultivation stretch from tropical latitudes to Scandinavia. In the world agriculture the area sown is 130-140 millions ha with 22-23% of it being in the USA and yielding up to 60% of the gross world cereal yield. Corn crops account for 20% of the world’s cereal cropping area. Brazil has 12.4 million hectares under crops, India has 5.8 million hectares and Argentina has 3.2 million hectares. There are large areas of crops in Mexico, some countries of south-eastern Europe (Romania, Bulgaria, Hungary), China.
The gross harvest of grain in the world is 600 million tons, or 29% of the gross cereal yield. The average yield is 4.2 t/ha. There are no statistics (on the whole world-wide) on production for green fodder and silage.
In the USSR in 1982 the area of maize sown for grain was 4.2 million ha, for silage and green fodder – 18.1 million ha. The main areas of cultivation are in the Stavropol and Krasnodar regions, in the Central Black Earth zone, Volga region, south of Siberia, as well as in Transcaucasia, Ukraine, Moldova, and Central Asia. For silage and green fodder, also in the Non-Black Soil Zone, Siberia and the Far East.
The average grain yield in 1980-1982 was 2.8 t/ha. The maximum yield under favorable climatic conditions in the main areas of cultivation (in the Ukraine, North Caucasus, Georgia, Azerbaijan and Central Asia) and a high level of agricultural technique reached 5.0-6.0 t/ha of dry grain, under irrigation conditions – up to 8.0-10.0 t/ha, silage mass – 80-100 t/ha.
Introduction of industrial technology of cultivation in the USSR in 1981 on the area of 2.37 mln ha provided an increase in yield compared with the traditional mechanized technology by 9.7 c/ha or 55%.
In the Non-Black Soil Zone, as well as in Belarus and the Baltic states, silage yields reach 50-60 t/ha of green matter.
In Russia the area under crops in 1997 was 0.92 mln ha (for grain), and in 2001-2005 – 0.7 mln ha (for grain). – In 2001-2005 the area under crops amounted to 0.7 mln ha. The areas sown for green fodder and silage in 1997 were 5.0 mln ha and 2.5 mln ha in 2001-2005. The average yield was 2.9 t/ha. The gross harvest of grain in 2001-2005 was 2 million tons. The gross harvest of fodder mass in 2001-2005 was 32.2 mln tons. – 32.2 million tons, with an average yield of 13.7 t/ha.
Botanical description
Corn is an annual plant, belonging to the Poaceae family. It is monoecious, separately-sexed, cross-pollinating. It is not found in the wild.
Root system
Corn root system is powerful, fibrous, multibranch, strongly branched, on soils with a loose subsoil layer can penetrate to a depth of 3 m, on chernozems – to 4 m. The radius of horizontal spreading is more than 1-1.5 m. The main mass of roots is located at a depth of 30-60 cm.
Anatomical peculiarity of the root system is the presence of air cavities which indicates that the roots are highly sensitive to the presence of oxygen. Up to 60% of the cavities are located in the arable layer.
Corn has a pattern: a new tier of root system is formed with the formation of a new pair of leaves.
The grain germinates with a single germinal root. Nodular roots of the first tier are formed on the underground nodes of the stem when 3-4 leaves appear, and those of the second tier when 5-6 leaves appear. During the phase of panicle formation, aerial (support) roots form from the stem nodes, which are closer to the soil surface, and prevent lodging of plants, and if there is enough moisture and dip, rooting takes place. The maximum development of the root system is in the phase of wax maturity. Its development is promoted by moisture content 70-80% of the lowest moisture capacity and optimum soil density equal to 1.1-1.3 g/cm3, the provision of accessible nutrients, especially phosphorus during the initial period. Under soil drought conditions root growth is suppressed, their branching decreases, the appearance of successive tiers of nodule roots is delayed, and the proportional formation of above-ground and underground parts of plants is disturbed.
Stem
The corn stem is 1.5 to 7 cm thick, well foliated, erect, rounded, smooth. Plant height varies from 50 cm to 7 m. The taller the stalk, the later the maturity comes.
The stem consists of heart-filled internodes separated by thickened stem nodes. The 3 to 5 converged internodes are located in the soil. Each node is covered by a leaf sheath. The number of nodes and, consequently, of leaves is a characteristic varietal trait. The stem is capable of branching, laying up to 2-3 lateral shoots.
The formation of grain yield depends on the photosynthetic activity of the stem. In experiments, when the stem was covered with light-tight paper, the grain yield decreased by 30%, when the cobs were covered – by 14%.
Leaves
The leaves are large, linear, entire-edged, parallel-nerved, pubescent on top, alternately arranged on two opposite sides of the stem. Leaf sheaths tightly enclose the stem. Tongue short, transparent, lugs often absent. The number of leaves on one plant varies from 8 to 45. Varieties common in Russia have 12 to 26 leaves. Early-ripening varieties have fewer leaves than late-ripening ones. Plants with narrow leaves bending at an acute angle to the stem have a higher yield because they shade each other less. Due to the grooved shape and oblique vertical arrangement of the leaves, the plants can use even small precipitation and dew flowing down the leaves and stem to the roots. This characteristic of corn increases the effectiveness of nesting or row fertilization.
The total leaf surface area is 0.3-1.5 m2, depending on variety and farming technique. The maximum leaf surface area is at the end of the flowering phase.
Leaves of one plant have up to 100-200 million stomata, which creates favorable conditions for gas exchange. Leaves contain more nutrients than the stem, so higher foliage of plants increases the quality of silage and green fodder.
Inflorescence
Each corn plant has two types of inflorescences: a male panicle and a female cob. The panicle consists of a central axis, which is a continuation of the upper internode, and lateral axes. The panicles are bicolored, with three anthers in a flower. A well-developed panicle contains 800-1200 spikelets or 2-2.5 thousand flowers. One anther yields up to 2,500 pollen grains, while the whole panicle counts 15 to 20 million.
The cobs are modified side-sprouts, located in leaf axils on the tips of side-sprouts with shortened internodes and modified leaves that form a wrapper. The number of developed cobs per plant may vary. Starchy, sugar and bursting late-ripening corn have the greatest number of cobs. Siliceous and toothed corn forms one or, less often, two cobs each.
The cob consists of an inflorescence axis (shaft), on which rows of spikelets with female flowers (200-1,000) are arranged in pairs. The spikelet contains two flowers, of which only the upper one develops while the lower one atrophies. The number of longitudinal rows of flowers (grains) is even, ranging from 8 to 16; some varieties may have as many as 30. The pistil has a large ovary and a very long column. During flowering, the pistils extend beyond the wrapper.
Most often, 1-3 cobs are formed on one plant, with the upper one being the most developed. The average weight of the cob is 200-300 grams.
Corn is pollinated by the wind. The panicle and cobs do not bloom on the same plant at the same time: the panicle blossoms 3 to 8 days earlier, thus cross-pollinating. Pollination benefits from warm, humid weather and a light breeze. Rainy weather washes away pollen and air drought kills it. Drought conditions increase the period between the flowering of male and female inflorescences. Unfavorable pollination conditions result in over-grain.
Fruit
The fruit of corn is a grain, usually glabrous and large. Weight of 1000 seeds in small-seeded varieties is 100-150 g, in large-seeded – 300-400 g. Grain color varies depending on the group and variety (hybrid), and may be white, cream, yellow, orange, red, etc. Depending on the variety and cultivation conditions, a corncob contains 200 to 1000 seeds, with an average of 500 to 600 seeds. Kernels consist of a shell, an endosperm, and a germ. The endosperm contains a floury and a horny part.
Leaves, stem, panicle, stem with stalk and wrapper account for an average of 55-60% of the total dry above-ground mass of the plant, while grains account for 40-45%. The latter accounts for 15-18% of the total mass of grain and stem.
Grain yield from the cob weight is 75-85%.
The male inflorescence accounts for 1-1.5% of the total aboveground mass. The ratios may differ for different varieties and depending on environmental factors and agricultural practices.
Subspecies
There are eight subspecies of corn based on the shape, chemical composition, and internal structure of the grains:
- toothed;
- siliceous;
- starchy;
- sugary;
- starchy-sugar;
- bursting;
- waxy;
- filmy.
In Russia, the most widespread are the toothed and siliceous corn, which are well suited for growing for grain and silage.
Tooth
Tooth corn (Zea mays L., indentata) is a common subspecies, relatively new to the crop.
Plants are tall; ears are short and thick.
The grain is large, elongate-prismatic, with an indentation on top. The dent on the top surface of the grain appears when the central soft-starch kernel is compressed during drying more than the surrounding hard endosperm.
On the sides of the grain, the endosperm is vitreous; in the center of the grain and at the top, it is floury.
Kernels contain 68-75.7% starch, 8-13.5% protein, and about 5% fat. Varieties and hybrids of this subspecies are relatively late maturing. It is mainly of fodder value.
Siliceous
Siliceous corn (Zea mays L., indurata) is one of the oldest subspecies by origin and has the largest area of distribution. It is the most cold-resistant, does not lodge, is resistant to diseases, less demanding to growing conditions, and has late-ripening and extremely early-ripening forms with small cobs. Has a food and fodder value.
Grain is large, hard, rounded, smooth, squeezed, glossy, with a thick pericarp. The endosperm is vitreous, has a high ratio of hard to soft starch with a small amount of soft floury opaque tissue in the center of the grain. Grain starch content is 65-83%, protein 7.7-18%, and fat up to 5%. Kernels of siliceous corn are the raw material for the production of flour used to make grits, bread products and groats.
The spikes are long and thin. Although sugar accumulation is much lower than sweet corn, immature ears are sometimes used as a vegetable, called “fried cobs.”
Starchy
Starchy corn (Zea mays L., amylacea) has the same grain shape as siliceous corn. Most of the grain is filled with soft floury (amylaceous) starch in the endosperm. The horn-like endosperm is absent or is represented only by a thin outer layer.
Grain starch content is 71.5-82.6%, protein 6.9-12.1%, fat 5%. It is widely distributed in the countries of Central Asia. Its grain is a raw material for the starch-making, distilling and butter-making industries.
Because of the thin pericarp, the grains are easily crushed, yielding high quality white flour that is used to make tortillas.
Sugar
Sugar or sweet corn (Zea mays L., sacharata or rugosa) comes from a mutation of the toothy and flinty varieties. It is considered relatively young in culture. In Russia, its cultivation is expanding.
It is distinguished by a large wrinkled angular grain, consisting of a translucent vitreous endosperm with luster at the break. The endosperm of the kernels initially accumulates sugars, but with increasing maturity accumulates various forms of starch, including water-soluble dextrin. Mature kernels are wrinkled, somewhat translucent. Kernels contain 13-20% protein, up to 74% carbohydrates, of which 32% are dextrin, and 8-9% fat. Pericarp tissue varies from thin to thick. Plant height is short to medium; cobs are small to medium.
Sugarcane corn is a vegetable crop, used in the canning industry. For food purposes the grain is used in the milk ripeness. The peculiarity is multistemming.
Bursting
Bursting or rice or popcorn corn (Zea mays L., everta) is the most ancient subspecies. It is characterized by a hard horny endosperm and a very thick pericarp, as well as small grains, often pointed. Moisture trapped in the grains when heated turns to steam and explodes the seed coat, exposing the expanded endosperm as white flakes. The kernels have a high ratio of starch to sugar. The plants and ears are usually small.
It is represented by two forms: rice with pointed kernels and pearl with rounded kernels.
The starch content of the grain is 62-72%, protein 10-16%. Used for the manufacture of cereals and flakes. Plants are characterized by good bushiness, foliage and multicobiety.
Waxy
Waxy corn (Zea mays L., ceratina) is a relatively new subspecies in culture.
Grain shape and hardness is similar to that of siliceous corn. The outer part of the endosperm is opaque, resembling wax in appearance because of its matte hue; the inner part is powdery. The grain consists almost entirely of amylopectin starch, which distinguishes it from other corn varieties with different ratios of amylopectin to amylose starch.
It is characterized by a high dextrin content. It is used to produce dextrin. Cultivated mainly in the USA and some European countries.
Filmy
Filmy corn (Zea mays L., tunicata) is characterized by loose cob structure and strongly developed bracts of female flowers that tightly cover the grain. It has no production importance.
Biological features
Temperature requirements
Corn is a thermophilic plant. Seed germination temperature is 7-10°C, and seedlings appear at 10-12°C. According to V.N. Stepanov and I.S. Shatilov (1959), the biological minimum of appearance of viable seedlings in siliceous varieties is noted at 10-11 °C, in toothy varieties – at 11-12 °C. The optimum germination temperature is 16-20°C. Too early sowing in cold and overwatered soil leads to seed failure and thinning of shoots. The optimal temperature for growth is 20-30°C; before the stage of hatching, it is 20-23°C. The maximum temperature at which growth stops is 45-47°C.
Sprouts appear at a sufficiently moist soil at a temperature of 20-25°C in 5-6 days.
Corn pollen contains about 60% of water and has a weak water-holding capacity. At temperatures above 30-35°C and relative humidity of less than 30%, it dries out and loses its ability to germinate within 1-2 hours after anthers cracking. This leads to poor cob performance.
Sprouts are damaged at 2-3 °C (according to other data, they satisfactorily tolerate frosts of -2 … -3 °C [V.V. Kolomeychenko, Plant Breeding], and leaves in autumn. Autumn frosts of -1,5 … -2 °C lead to frosting of leaves, resulting in a sharp decrease in the quality of green mass, for example, reduced carotene content. At the same time, such frosts in a phase of wax maturity of grain are not dangerous for cobs.
Corn is less susceptible to spring frosts than fall frosts. Damaged seedlings may regrow within a week. Northern early-ripening varieties are better at tolerating low temperatures and frosts than southern late-ripening varieties and hybrids. Plants killed by autumn frosts are suitable for haying or ensilaging. But do it immediately after frosts, as frozen plants tend to rot quickly. A frost of 3 °C leads to loss of germination of moist, unripe grain.
In the Non-Black Soil Zone, there is a correlation between the daily leaf productivity and the daytime air temperature (correlation coefficient +0.8). The higher the daytime temperature, the higher the leaf productivity. Biologically active temperature for corn is higher than 10-12 ° C, at lower temperatures growth and development processes are practically stopped. At the same time plants begin to turn yellow, are more susceptible to damage by pests and diseases. The sum of biologically active temperatures for ripening early maturing varieties is 1800-2100 °C, medium maturing and late maturing varieties – 2300-3000 ° C. Medium-ripening and late-ripening hybrids differ in the sum of temperatures necessary to reach the phase of panicle formation, and require almost the same sum of temperatures for subsequent phases.
Moisture requirements
Corn is a mesophyte in terms of moisture requirements. It takes from 160 to 406 m3 of water to create 1 ton of dry matter, which is less than that of oats and barley. However, due to significantly higher yields, the total amount of moisture consumed during the growing season reaches 3000-6000 m3/ha. At high yields water consumption increases. Corn effectively uses precipitation of the second half of summer and partly of autumn. The plants are able to accumulate a large organic mass even in arid regions, aided by a well-developed root system.
During swelling, the seeds consume about 44% of water of their own mass.
In the initial phases of development, the average daily consumption of water is 30-40 m3/ha, in the period from the formation of panicles to the milky state of the grain – 80-100 m3/ha. Under rainfed conditions in arid areas, corn gives a good yield in years with precipitation of at least 200 mm in June-August, and with good reserves of moisture in the soil in spring – at least 100 mm with a predominance in July during flowering.
According to the data of the Department of Crop Production of the Kuban Agricultural Institute, water consumption per 1 ton of grain in the conditions of the central zone of Krasnodar Territory is 60-92 mm, depending on moisture conditions and agrotechnics. In the southern arid regions, there is a positive correlation between leaf productivity and precipitation and a weak positive or negative correlation between leaf productivity and increased temperature (Volodarsky, 1975).
Corn tolerates drought relatively well until the emergence of the tube phase. The critical period occurs 10 days before emergence and lasts up to 20 days after, the lack of moisture during this period leads to a sharp decrease in yield. During this period, pollen is formed and seed formation begins. Abundant water supply at the beginning of vegetation, irregular or insufficient watering in the subsequent period reduces the grain yield. Lack of moisture during the critical period, including due to violation of agrotechnics, becomes the cause of unstable yields in the arid steppe.
With a high level of agrotechnique corn resists soil and air drought quite well. This is due to the fact that by the time of the most intensive water consumption, plants have time to develop a powerful root system, which provides the needs of plants. Corn is inferior to sorghum and millet in drought tolerance.
Corn plants can tolerate temporary lack of moisture in the soil and low relative air humidity. However, prolonged leaf binding results in inhibition of growth processes and disturbance of reproductive organs formation. Optimal wetting conditions are created when the humidity of root-containing layer is not less than 75-80% of the lowest moisture capacity. Under irrigation, active root absorbing surface increases, photosynthesis productivity, water content and water-holding capacity of leaves increase, and non-productive respiration decreases.
Corn negatively tolerates overwatering of soil, while sharply reducing grain yields. Excessive moisture leads to lack of oxygen, slows down the flow of phosphorus into the roots, resulting in decrease of total, organic and nucleic phosphorus, disrupts phosphorylation and energy metabolism in roots, protein metabolism.
Light requirements
Corn is a short-daylight plant. It blossoms most quickly when the daylight hours are 8-9 hours. The 12-14 hours of daylight lengthens the growing season. Corn requires intensive sunshine, especially in the initial stages of development. Therefore, excessive overgrowth or overgrowth leads to a decrease in cob yield. In experiments, the Department of Plant Industry, Moscow Agricultural Academy at the density of 63 thousand / ha of plants illumination of the leaves of the middle layer was 53%, the lower – 29% of the illumination of the upper leaves, whereas at densification of 150 thousand / ha of plants 23% and 10%, respectively. Net photosynthetic productivity in this case decreased by 15-30%.
Lack of light leads to inhibition of formation of fruiting organs, increasing the period between flowering of male and female inflorescences and the number of barren plants.
Soil requirements
Corn yields are high on clean, loose, air-permeable soils with a thick humus layer, sufficiently supplied with nutrients and moisture, pH of 5.5-7.5. Black-soil, dark chestnut, dark gray loamy and sandy loam soils, as well as floodplain soils are optimal.
High yields of corn for silage may be obtained on sod-podzolic soils, dried peat-bog (with deep groundwater) soils of the Non-Black Soil Zone under the condition of high agrotechnics. Unsuitable for growing prone to swamping, highly saline and acidic (pH below 5) soils. Heavy and compacted soils are also undesirable for its cultivation.
At germination seeds require good aeration, as large germs absorb a lot of oxygen. High yields are ensured when the oxygen content in the soil air is at least 18-20%. At less than 10% oxygen content, root growth slows down, and at 5% it stops. This disturbs the absorption of water and nutrients, metabolism in the roots and above-ground parts of plants.
Optimal soil density is 1.1-1.3 g/cm3.
Nutritional requirements
Absorption of the main nutrients follows a single-vein curve and corresponds to the course of dry matter accumulation.
Nitrogen is of great importance in the early stages of development. Its deficiency during this period leads to delayed growth and development of plants. The maximum nitrogen intake is observed during 2-3 weeks before the formation of the panicle. The critical period of nitrogen consumption is during the phases of flowering and seed formation. Nitrogen consumption stops after the beginning of milk maturity phase of grain.
Phosphorus is needed at the beginning of plant growth, especially when future inflorescences are put in place, i.e. in the phase of 4-6 leaves. Lack of phosphorus during this period leads to incomplete development of the cobs and the formation of irregular rows of seeds. Sufficient supply of plants with phosphorus promotes root development, increases resistance to drought, and accelerates cob formation and yield ripening. Phosphorus is absorbed by plants in smaller amounts, and its intake is slower and more even than that of potassium and nitrogen. Maximum intake occurs during grain formation and lasts almost until ripening.
Lack of potassium leads to slow movement of carbohydrates, reduces the synthetic activity of leaves, weakens the root system and lowers the resistance of corn to lodging. Potassium starts to be intensively absorbed by plants from the first days of seedling emergence. By the beginning of the phase of panicle formation, plants absorb up to 90% of potassium. After flowering, potassium intake stops (or rather stabilizes). From the phase of milk maturity of the grain, the content of potassium in plant tissues decreases due to its leaching by precipitation and exo-osmosis through the root system into the soil.
According to K.P. Afendulov and A.I. Lantukhova (1978), accumulation of dry matter in stems and in the phase of milk-wax maturity of grain in leaves stops and the increased transfer of nutrients from vegetative organs to reproductive organs starts with the beginning of grain formation. At the same time, up to 59% of nitrogen from other plant organs, 36% of phosphorus and 82% of potassium are used to fill the grains. The remaining amounts of nitrogen, phosphorus and, in some cases, potassium go into the grain due to the continuing consumption of elements from the soil.
On sod-podzolic and gray forest soils, on leached and podzolized chernozems, corn responds primarily to nitrogen fertilizers; phosphorus fertilizers are most effective on typical and ordinary chernozems; potassium ones – on sandy loam, peat and flood plain soils, and also in case of potassium-loving predecessors – beets, potatoes, grass.
Vegetation
Vegetation phases:
- sprouting;
- leaf formation;
- emerging into the tube;
- lancing (forming) of panicles;
- flowering;
- milky state;
- waxing ripeness;
- full ripeness.
The duration of the phases depends on the variety, weather conditions, and agricultural practices.
In the middle belt of the European part of Russia for common hybrids and varieties, the period from sprouting to flowering is 50-55 days, from fertilization to grain ripening is 35-60 days.
In the first 25-30 days after sprouting, before the formation of the first above-ground stem knot, plants develop slowly, which should be taken into account when building a plant protection system against weeds. The most intensive growth occurs during the period from the beginning of internodes growth to panicle formation. During this period, under favorable conditions, the growth rate reaches 10-12 cm/day. Growth in height stops after the flowering phase.
The critical growth phases of corn that determine yield are:
- phase 2-3 leaves, when rudimentary stem differentiation occurs;
- phase of 6-7 leaves, which determines the size of the cob.
Important developmental phases also include:
- formation of the panicle, occurs in early maturing varieties in the phase of 4-7 leaves, medium maturing – 5-8 leaves, late maturing – 7-11 leaves;
- forming the cob comes in early maturing varieties at the phase of 7-11 leaves, medium maturing – 8-12 leaves, late maturing – 11-16 leaves.
Corn accumulates up to 75% of organic mass 10 days before and 20 days after flowering (i.e. in the critical period of moisture consumption). Drought, excessive moisture in the soil, lack of mineral nutrition during flowering and fertilization reduce fertilization and the number of grains (granularity) of cobs.
Plants accumulate the maximum amount of crude weight in the milky phase; dry matter is accumulated at the end of the waxy-ripening phase of the grain. To get a high yield of grain crops should form the total area of the leaf surface of not less than 40-50 thousand m2/ha, for green mass – not less than 60-70 thousand m2/ha.
The correlation between the length of vegetation period and the number of leaves per plant (correlation coefficient 0.82-0.99), and between the length of vegetation period and grain yield (0.70) was established (Volodarsky, 1975).
The growing season of corn lasts from 70 to 180 days. According to the length of the growing season, a distinction is made:
- early-ripening with a duration from sprouting to full grain maturity of 80-90 days, the number of leaves on the main stem 10-12 pieces;
- medium-early maturing – 90-100 days, the number of leaves 12-14;
- medium-ripening – 100-115 days, number of leaves 14-16;
- medium-late maturing – 115-130 days, number of leaves 16-18;
- late-ripening – 130-150 days, number of leaves 18-20;
- very late-ripening – more than 150 days, number of leaves more than 20.
Crop rotation
In field crop rotations corn is usually placed after winter cereals, leguminous crops, as well as after potatoes, sugar beets, melons and other row crops, also when harvesting for silage – in the fallow. In areas with insufficient moisture maize is not placed after sunflower and sugar beet, as they strongly dry out the soil to a great depth. In addition, sunflowers strongly clog crops with shattered seeds, and placement after beets reduces the availability of phosphates.
Millet is considered an unfavorable forecrop for corn, as they have a common pest, the corn moth.
In Siberia, spring wheat is a good precedent for corn, coming after perennial grasses or one year after them.
The predecessor is especially important in dry years.
At Zherebkovskaya experimental station All-Union Scientific Research Institute of Corn in Odessa region of Ukraine on average over 7 years, corn yield after peas 6.21 t/ha, after winter wheat 5.99 t/ha, after corn 5.4 t/ha, after sugar beet 5.13 t/ha.
According to the Voronezh Experimental Station of the All-Union Corn Research Institute for three years, the corn yield after legumes was 3.66 t/ha, after corn for silage – 3.53 t/ha, after winter wheat – 3.28 t/ha, after sugar beet – 2.61 t/ha. In experiments Krasnograd experimental station All-Union Scientific Research Institute of maize in Kharkiv region of Ukraine on the chernozem soil on average for ten years, the maximum yield of 3.42-3.51 t/ha was after winter wheat and china. After corn for grain and silage yield of grain was 3.13 t/ha and 3.23 t/ha, after sugar beet – 0.20-0.29 t/ha less than after winter wheat and chinna.
Table. The influence of predecessors on corn yield (Erastov Experimental Station of the All-Russian Research Institute of Corn)
| Winter crops after fallow | ||
| Legumes | ||
| Sunflower | ||
| Barley | ||
According to the Don Research Institute of Agriculture, the best predecessors in the Rostov region are leguminous crops and winter wheat, after which the soil is cultivated on the type of half-fallow. In the southern regions, corn may be cultivated as a stubby crop, obtaining two crops per year and harvested in the phase of milk-wax ripeness. Post-mowing crops after fodder crops for green fodder and silage are also widespread.
Corn, especially grown for silage, is a good precedent for many crops, including winter wheat and spring cereals.
If it is necessary to saturate crop rotations with corn it may be cultivated repeatedly. High yields are possible if the fertilizer system and the full agrotechnical complex are followed. Yields decrease if fertilizers are not sufficiently applied and the system of plant protection against pests, diseases and weeds is not satisfactory.
According to the results of experimental data corn in the conditions of the central steppe of Ukraine can be grown continuously with periodic interruptions in specialized corn rotations with a short rotation:
1, 2, 3 – corn; 4 – peas;
1, 2 – corn; 3 – corn for silage; 4 – winter wheat.
These crop rotations are convenient for farms with dairy and meat (beef or pork) specialization.
In many regions of Russia corn-alfalfa rotations are effective, in which every 4-5 years corn and alfalfa alternate, and 7-10 thousand/ha of fodder units are obtained.
In the Non-Black Soil Zone corn can be grown in the non-rotation fields of crop rotations, on so-called permanent plots, with stable annual yields of green mass. Cultivation on lead fields is especially advisable in farms with little fertile land, and fields differ in fertility and are distant from farms. This is important in areas with poor soils, where corn is effectively placed in floodplains and other fertile areas. Placing it on permanent plots close to farms eliminates the need to transport fertilizer and crops over long distances.
The ability of corn to tolerate permanent crops is due to the large mass of organic residues that remain in the field each year, the small accumulation of bladderwort pathogens in the soil, and the reduction of infestation of repeated crops as a result of inter-row treatments and herbicide applications. Good results in the Non-Black Soil Zone are also obtained by including corn in forage crop rotations with a short rotation and by alternating with potatoes, root crops, and vegetable crops.
According to the data of a large experimental material and the experience of the advanced farms, the best corn predecessors in different soil and climatic zones are considered:
- in the Non-Black Soil Zone (for silage) – winter crops, potatoes, root crops and crops under which a sufficient amount of fertilizers, perennial grasses and one year after them; also permanent plots (non-rotation fields);
- in the Central Black Earth zone – leguminous crops, winter cereals, potatoes, in areas with sufficient moisture also sugar beet;
- in the South-East of Russia – leguminous crops, vegetable and melons, winter and spring cereals;
- in the North Caucasus, Ukraine and Moldova – winter cereals, leguminous crops and melons, in areas with sufficient moisture also root and tuber crops;
- in Transcaucasia – leguminous and cereal crops;
- in Central Asia and southern Kazakhstan – leguminous and cereal crops, cotton.
Fertilizer system
During the growing season corn consumes a large amount of nutrients. For the creation of 1 ton of grain and the corresponding amount of leaf-stem mass it consumes on average 24-30 kg of nitrogen, 10-12 kg of phosphorus and 25-30 kg of potassium. With a yield of 5-6 t/ha of grain or 50-60 t/ha of green matter about 150-180 kg N, 60-70 P2O5 and 160-190 kg K2O are absorbed from soil. More than half of the nutrients are absorbed from the soil during the second half of the growing season, so fertilizing in summer and the wide-spaced method of sowing, which allows fertilizing during the growing season, become important.
The corn fertilization system includes:
- basic fertilizer, which is applied in the fall or spring before sowing;
- pre-sowing (local);
- top dressing during the growing season.
Basic fertilizer
The basic fertilizer is designed to meet plant nutrient needs throughout the growing season. Depending on soil fertility apply 20-40 t/ha of manure and compost. Under conditions of insufficient moisture organic fertilizers are applied under the predecessor in an amount of 10-20 t/ha. For the Non-Black Soil Zone it is recommended to apply 30-40 t/ha of manure, in the southern regions – 15-20 t/ha.
According to the All-Russian Institute of Corn, the introduction of 20 t/ha of manure in the steppe zone on ordinary chernozem increases the yield of grain by an average of 0.4-0.6 t/ha. Under conditions of sufficient moisture on leached chernozems and podzolic soils of the forest-steppe and Polissya – by 1.0-1.5 t/ha. In the experiments of the Research Institute of Agriculture of the Central Black Earth zone grain yield with the application of 15 t/ha of manure was 4.74 t/ha, without fertilizers – 4.09 t/ha.
In the Non-Black Soil Zone, the average increase in green matter yield upon application of 20-40 t/ha of manure amounts to 8-10 t/ha. Corn is responsive to the effects of organic fertilizers. Their effectiveness increases when mixed with mineral fertilizers. Payback at the expense of 1 kg of nutrients, introduced with mineral fertilizers, depending on soil and climatic conditions is from 4 to 13 kg, under irrigation – up to 19 kg of grain.
To determine the norms of fertilizer application use balance methods that allow you to make fertilizers for the planned yield. When calculating the rates take into account the predecessors, the effect of previously made fertilizers, soil and climatic conditions.
Table. Approximate application rates of the main fertilizer for corn[1]Crop production / P.P. Vavilov, V.V. Gritsenko, V.S. Kuznetsov and others; Ed. P.P. Vavilov. – 5th ed., revised. and additional - M.: Agropromizdat, 1986. - 512 p.: ill. - (Textbook and textbooks … Continue reading
| Non-chernozem (sod-podzolic, gray forest) | |||||
| Forest-steppe (gray forest, podzolized, leached, typical chernozems) | |||||
| Steppe (ordinary chernozems, carbonate, southern, chestnut soils) | |||||
| Irrigated areas (chernozems, chestnut soils, gray soils) | |||||
* For Polissya and western regions of Ukraine.
Note. Under production conditions, the optimal application rates are specified in accordance with the results of agrochemical surveys.
On chernozem and dark chestnut soils 30-40 kg/ha of phosphorus and potassium are applied in the basic fertilizer. On sod-podzolic and other low fertility soils – 45-60 kg/ha of phosphorus, 40-50 kg/ha of potassium.
Pre-sowing (row) fertilizer
Row fertilization is designed to meet the needs of plants in phosphorus at the beginning of growth. For this purpose, granulated superphosphate in the rate of 5-15 kg/ha a.s. is applied in rows during sowing by seeding machines equipped with fertilizer sowing units, which allow placing fertilizer in the soil at 3-5 cm deeper than the seed sowing and at 2-3 cm to the side. Row fertilization promotes initial growth of corn, which is important when sowing in poorly warmed soil and when seedlings poorly absorb phosphorus.
Local application of superphosphate at the rate of 5-10 kg/ha a.s. in steppe areas increases corn yields by 0.25-0.5 t/ha.
Recommended fertilizer rates: for chernozems and dark chestnut soils during spring cultivation 20-30 kg/ha of nitrogen and phosphorus are applied in rows. On sod-podzolic and low fertility soils, 50-60 kg/ha of nitrogen is applied.
In the forest-steppe and more northern areas, joint application of phosphorus fertilizers with nitrogen and potassium 5-10 kg/ha N and K2O is more effective. In all zones, the addition of dry crushed poultry manure to mineral fertilizers during row application gives good results.
Top dressing
Top dressing is used when soils are insufficiently stocked with basic fertilizer on light soils, in years with a cold spring and during irrigation. However, it is not advisable to transfer part of the basic fertilizer application rate into top dressing. Early feeding with nitrogen fertilizers, such as ammonium nitrate or ammonia water, in the phase of 3-5 leaves is effective.
For fertilizing on the chernozem soils of the steppe zone it is better to use nitrogen and phosphorus fertilizers, in the forest-steppe and more northern areas – full mineral fertilizer. Rate of application is up to 20-30 kg/ha a.s.
Fertilizer composition can be determined by leaf diagnostics. In nitrogen deficiency, corn plants show low growth, with small leaves of pale green or pale yellow color. Excess nitrogen is manifested by intensive growth of the above-ground part, which further negatively affects the formation of cobs.
Deficiency of phosphorus is manifested by slow growth at the beginning of vegetation, the lower leaves are dark green or purple-purple color, purple color appears on the edges, the cobs are formed ugly with crooked rows of grains.
Potassium deficiency is manifested by stunted growth of the stem, wavy dark green leaves, pale at first, then turning yellowish-green or dark brown at the edges, later the leaves turn yellow, the tips and edges dry up. The cobs form puny with poor grain performance.
Magnesium deficiency is manifested by the appearance of longitudinal light yellow stripes along the veins of old green leaves, which then turn white. As a result, the leaves become striped. In this case, 50-60 kg/ha of MgO is applied. The same amount of magnesium is contained in 30 t/ha of manure.
Zinc deficiency is manifested by the light green color of the seedlings. Yellowish streaks appear between the leaf veins. An excess of phosphorus and calcium in the soil leads to signs of zinc deficiency.
Manganese deficiency, which often appears in carbonate soils, causes leaf chlorosis in the form of yellow and gray spots between the veins on older leaves.
Fertilizing is carried out in advance, before the onset of strong signs of plant starvation.
Nitrogen fertilizers are better to make fractional: 50-60% in the spring before tillage (in ammonium form), the remaining amount (in nitrate or amide form) – in top dressing. Fertilizing begins in the phase of formation of 4-6 leaves. Fertilizer is applied by cultivator-plant feeders in a moist layer of soil. Ammonia water can be used for top dressing in all Russian areas. Recommended fertilizer rates for black and dark chestnut soils – 20-30 kg/ha of nitrogen and phosphorus, 15-20 kg/ha of potassium; for sod-podzolic and low fertility soils – 20-30 kg/ha of nitrogen and phosphorus.
Fertilization with nitrogen fertilizers in the phase of grain formation, when growth is completed, contributes to an increase in crude protein content in corn plants. Nitrogen fertilizer absorbed by leaves increases protein and non-protein content in plant tissues. A 30% urea solution is used for foliar aerial top dressing. Norm of nitrogen, which is usually 30-60 kg/ha a.s., depends on the condition of the crops: the better developed the plants and the greater their vegetative mass, the higher dose of nitrogen can be made.
According to the All-Russian Scientific Research Institute of Corn, spraying of plants in 10-15 days after flowering with 30% urea solution at a rate of 45 kg/ha a.s. nitrogen increases the content of crude protein in green mass in the phase of milk-wax ripeness of grain on average by 22%.
Microfertilizers
Microfertilizers contribute to higher corn yields. Corn plants are often deficient in boron, manganese and zinc.
Boric fertilizers are used on sod-podzolic, sod-gley, red soil, humus-carbonate, leached chernozem, gray soil and marsh soils. Manganese fertilizers are applied to weakly leached chernozem, gray forest, solonetz and chestnut soils. Zinc fertilizers are used on sod-carbonate, chestnut, brown, gray soil, gray-meadow, neutral sandy and chernozem soils.
Deficiency of boron is especially strong in calcareous soils. Boron fertilizer is applied to soil in the form of boron-enriched superphosphate, boric fertilizer or boric acid; it is applied to seeds or carried out foliar fertilizing. Application of boric fertilizers increases corn yield by 0.4-0.7 t/ha, green mass by 4-8 t/ha. Superphosphate enriched with manganese or manganese sulfate can be used as manganese fertilizers. On acidic and over-moistened soils an excess of manganese can be noted. Higher doses of mineral fertilizers, especially phosphorus and calcium, increase the need for zinc, which is brought in the form of zinc sulfate (8-15 kg/ha) or polymicrofertilizer. Copper fertilizers are used on peat soils. Application of a full dose of organic fertilizer in most cases eliminates micronutrient deficiencies.
Diagnosis of corn nutrition
Main article: Diagnosis of corn nutrition
Tillage system
Main tillage
Methods and depth of main tillage for corn are determined depending on the predecessor, soil differences, thickness of the humus layer, weed infestation of the field. In autumn, in most cases, discing and deep autumn plowing are carried out. Disking is not carried out on fields clean of weeds.
According to the recommendations of the All-Russian Scientific Research Institute of Corn, stubble discing is carried out twice in fall on weedy fields: the first – shallow, the second, after weeds regrowth – deeper. Then the autumn plowing with plows with skimmers. The most complete destruction of weeds is achieved by discing to a depth of 6-10 cm, followed by plowing at 28-32 cm. In this case up to 80% of weeds are destroyed, the number of seeds in the soil is reduced by 50%, and corn yield increases by 0.30-0.33 t/ha of corn compared with plowing to the same depth without discing.
If the arable horizon is shallow, plowing to full depth with tillers and fertilizers is carried out.
Fields after row crops clean of weeds can be ploughed without prior discing.
On chernozems of the steppe zone when increasing the plowing depth to 30-35 cm, especially with the introduction of organic and mineral fertilizers, grain yield increases by 0.6-1.0 t/ha, green matter – by 4-6 t/ha, compared with conventional plowing at 20-22 cm.
Continuous plowing at the same depth leads to the formation of a plow pan. This compacted layer makes it difficult for the corn roots to penetrate deeper horizons, reducing water inflow and worsening plant nutrition conditions. Therefore, in the rotation use differently deep plowing, taking into account the biological properties of cultivated crops.
When corn is repeatedly sown on the same field, slow decomposition of stubble and root residues is observed. As a result harrowing, seeding, cultivation become complicated, soil nutritive regime worsens, and conditions for reproduction of stalk moths are created. Technology of soil preparation in case of repeated sowing consists of: low cutting of corn stalks (not more than 15 cm) during harvesting, pre-tillage discing of fields in one or two directions, and plowing to a depth of not less than 30 cm by mouldboard plows with skimmers. Qualitative entry into the soil stubble and root debris is also achieved by plowing plows equipped with special blades attached to the legs skimmers, and expanders bottom plow furrows, which are mounted on all plow bodies. Good results are also achieved with milling.
In the Kuban, Volga and Central Black Earth zones, the method of soil preparation by the type of half-fallow is often used.
In areas at risk of wind erosion, deep non-moldboard loosening is used. For this purpose, use special tools with flat-cut working tools, such as КПГ-250, КПГ-2-150, as well as flat-cut-deep-looseners, which allow to keep the stubble of crops on the soil surface.
Acidic soils are lime treated at the rate of 3-5 t/ha of lime.
In steppe areas, snow and melt water retention techniques are used.
Spring tillage
Spring tillage for corn includes moisture conservation and weed elimination techniques. It consists of early spring harrowing, 2-3 cultivations with simultaneous harrowing.
The first cultivation is carried out in early terms at a depth of 10-14 cm. After emergence of weeds perform pre-sowing cultivation to the depth of sowing seeds with simultaneous harrowing. In the absence of weeds it is enough to carry out one cultivation. Under conditions of sufficient moisture and manure application in spring, the first cultivation is substituted by spring plowing with plows with mouldboards removed but with skimmers set on depth 12-14 cm.
On heavy and very settled soils perform deep loosening chisel-cultivators or multi-ploughs without mouldboards with simultaneous harrowing.
Effective methods of soil preparation for corn are pre-sowing leveling and rolling the soil, which allow to further reduce damage to plants when harrowing on the shoots and the treatment of intercrops, and also contribute to a faster warming of the soil, the emergence of weeds and qualitative performance of subsequent techniques.
Application of minimum tillage methods, i.e. combination of several operations with one pass of machinery allows to carry out preparation, sowing, crop care and tillage of next crops faster and with higher quality without soil pulverization. Domestic or imported combined units are used for these purposes.
Seeding
Preparation of seeds
Preparation of corn seeds for sowing consists of calibration and dressing at special enterprises. Calibration allows the use of precision seeders and avoids sparse seedlings. Corn seeds germination should be not less than 96% for I class or 92% for II class.
Seeds are dressed with 80% solution of TMTD, fentiuram at the rate of 2 kg of the preparation per 1 ton of seeds. Under the threat of spreading of wireworms and moth caterpillars, seeds are treated with heptachlor (1 kg/100 kg of seeds) or HCCH (up to 2 kg/100 kg of seeds).
Additional treatment with microfertilizer solutions is possible: boric acid 0,01-0,03% solution; manganese sulfate 0,03-0,05% solution; copper sulfate 0,001-0,005% solution; zinc sulfate 0,03-0,05% solution.
To increase field germination, which is especially important under unfavorable weather conditions or early sowing, hydrophobization, incrustation or air-heat treatment (3-5 days) of seeds is carried out.
Incrustation is treatment of seeds with a solution of polymer and etchant mixture to create a protective film. Components included in the hydrophobic film are dissolved in technical chloroform and applied to seeds in the form of a solution. To treat 1 ton of corn seeds we need 11 liters of chloroform, 0.5 kg of polystyrene and 2 kg of fentiuram.
For seed dressing against dusty and bubble smut, seed mold, root and stem rot, the preparations Vitavax (375 g/kg carboxin + 375 g/kg thiram) and Premis Dvusti (200 g/l triticonazole) are used.
Timing of seeding
To determine the timing of seeding corn, take into account the weather conditions of spring and the warming of the soil. It is necessary to choose such an early sowing date, in which sprouts will appear quickly, and the subsequent development phases will pass at the most favorable temperature regime. Sowing begins when the soil warms up to 10-12°C at the seed embedding depth. On fertile, well fertilized, unweeded plots, sowing can be carried out at 8-10°C, using cold-resistant varieties and hybrids. Sowing is carried out in mature, well-tilled soil. Sowing is first carried out on weed-free and light, quickly warming soils.
Corn is also sown after mowing and in stubble crops (second crops). In this case, the stubby crops can produce large yields of silage with the cobs in the milk-wax ripeness and green fodder, and after mowing – also grain.
Methods of seeding
The methods of seeding corn for grain and silage are spaced and wide-row. Spaced sowing requires a higher culture of farming, the use of herbicides to control weeds. High efficiency is given by no-thinning spaced sowing, which sows exactly a given number of seeds, which is possible with quality tillage, high field germination of seeds, adjustment of precision planting machine and complete absence of wireworms and false wireworms, thinning sprouts.
With precision spaced sowing the distance between the plants in the row depends on the density of standing and can be from 13 to 43 cm. Row spacing in conditions of sufficient moisture, ie with an average annual rainfall of 500-600 mm, is 70 cm, in areas with unstable moisture – up to 100 cm. In the southern arid areas with an average annual rainfall of 300-400 mm, it is advisable to conduct drilling by the scheme 210 +3×140 cm crops with the processing of inter-row in the second half of the growing season highly wedge cultivators.
Spaced seeding is carried out by pneumatic seeders, for example, СУПН-8, СУПН-6, СПЧ-6М, СКПП-12.
In the Non-Black Soil Zone corn for silage and green fodder is usually sown in wide-row method with 70 cm row-spacing. With good moisture and growing for green fodder, the width of row spacing can be 45 cm, 30 cm, 15 cm.
In dry conditions and when cultivating high-stem hybrids, the width of the row spacing is 90-140 cm (maximum up to 210 cm), low-stem hybrids – 60 cm. In wet conditions, the width of inter-row space is reduced to 60 cm.
In the conditions of overwatering of the Far East, this culture is sown on ridges.
Sometimes, the practice of sowing in the furrows, which makes it possible to carry out dip, contributing to the development of additional aerial roots.
Seeding rates
The optimum density of corn crops of different early maturity for a particular soil and climate zone is determined taking into account the moisture reserves in the soil at the time of sowing, statistical data on the average annual precipitation during the growing season, and economic and biological characteristics of hybrids and varieties.
The sparse standing of plants leads to incomplete use of nutrients and soil moisture, resulting in lower yields, despite the fact that the productivity of individual plants can be high. As standing densities increase, the yield of total above-ground mass and grain increases, but only up to a certain limit, after which increasing standing densities leads to lower yields. With severe densification the plants begin to shade and suppress each other, which is associated with poor root development, inhibition of growth processes and reduced intensity of photosynthetic processes. Densification of crops leads to a decrease in the number of cobs per plant, average cob weight, incomplete grain formation in the cob, grain yield, weight of 1000 grains. Such crops are more severely affected by fusariosis, diplodiosis, corn moth.
Optimal density of plant stand allows plants to fully manifest useful productivity, effectively use the supply of moisture and nutrients of soil, provide a high intensity of leaf photosynthesis.
Table. Optimal density of corn plants depending on soil and climatic zone and hybrid at industrial technology of cultivation[2]Plant breeding/P.P. Vavilov, V.V. Gritsenko, V.S. Kuznetsov et al; Edited by P.P. Vavilov. - M.: Agropromizdat, 1986. - 512 p.: ill. - (Textbook and Tutorials for Higher Education Institutions). … Continue reading
| Central Black Earth | |||
| Volga Region | |||
| Krasnodar Territory, Rostov Region | |||
| Polesie | |||
| Steppe of Ukraine: | |||
| - southern | |||
| - central | |||
| - northern | |||
| Forest-steppe of Ukraine: | |||
| - southern | |||
| - central and northern | |||
| Kazakhstan | |||
| Moldova | |||
| Uzbekistan | |||
All-Russian Scientific Research Institute of Corn recommended in the most arid southern and southeastern regions with an annual rainfall of 300-400 mm to place 20-25 thousand plants/ha, in the steppe regions with unstable moisture and the amount of rainfall 400-500 mm – 30-40 thousand/ha, in areas with sufficient moisture – 40-60 thousand/ha. It is necessary to keep optimal number of plants by the time of harvesting. High-growing hybrids or varieties with strong development, give higher yields at lower density of standing than low-growing and more early-ripening varieties. For early-ripening varieties or hybrids, the density of sowing is increased by 20-25% compared to medium-ripening ones, for late-ripening ones it is reduced by 15-20%.
Under irrigation conditions in arid areas the density of plants is increased. In this case, provided a sufficient amount of nutrients in the soil, the limit of densification of crops is set by the lightness of plants, especially the leaves of the lower and middle tiers. Leaves of the lower tiers begin to be increasingly shaded, and at a certain point, the overall photosynthetic productivity of crops begins to decrease.
Sowings of corn for silage with cobs in milk-wax ripeness and for silage without cobs are thicker than when growing for grain. In the zone where the crop matures at harvesting for silage in the phase of milky-wax and wax maturity the density of standing can be 10-15% higher compared with sowing for dry grain.
When growing corn for green fodder the density of standing should be 100-120 ths./ha in dry areas, and 120-200 ths./ha of plants in more humid areas. Seeds for green fodder, especially when corn is planted by stubble, after mowing or in seeded fallow, are sown by ordinary grain drills with density up to 300-500 ths./ha. The earlier the harvesting dates of corn for green fodder, the higher the density can be. With late corn sowing high density of standing also allows you to get a higher yield of green mass.
In the Non-Black Soil Zone when growing corn for silage with cobs in the milk-wax maturity the density of plants is 80-120 thousand / ha, and when harvesting to this phase density increase to 200-300 thousand / ha. At 300,000/ha, there may be a strong lodging in the wind or in rainy weather.
To determine the weight norm of seeding take into account the size of seeds, field germination and thinning of plants during the growing season. Field germination is always less than laboratory germination. It is also necessary to take into account the additional thinning during mechanized maintenance of crops (harrowing, inter-row weeding with weeders, etc.). For this reason, to achieve optimum density of plants, the seeding rate is increased by 15-40% of the number of plants per hectare actually needed for harvesting. The correction can be reduced with favorable weather conditions, high level of agrotechnics and treatment of crops by experienced machine operators.
Calculation of increase of seeding rate for compensation of thinning from mechanical tillage may be made by the following conventional data: the rate is increased by 6-8% per each harrowing on sprouts; by 4-5% per each inter-row tillage.
The weight norm of corn seeding for grain is 10-25 kg/ha, for silage and green fodder – 30-100 kg/ha.
Seed sowing depth
The depth of sowing corn seeds for grain is 6-10 cm, with drying of the top layer, light soils, distribution of rooks – 10-12 cm.
In the Non-Black Soil Zone, especially on heavy soils, as well as when sowing in insufficiently warmed soil (9-10 ° C) and early sowing, the depth is 4-6 cm. It is important to sow in a moist, sufficiently compacted layer of soil.
During sowing, it is effective to conduct simultaneous rolling with ring-spiked rollers, except for heavy soils, especially in wet weather.
Joint crops with legumes and other crops
The cultivation of corn for silage and green fodder is widely used joint crops with leguminous crops. In the south of Russia the best components are high-stemmed soybeans, in the Non-Black Soil Zone – lupine and fodder beans.
Table. Efficiency of mixed crops of maize with soybeans in the steppe zone of Ukraine (All-Union Research Institute of Corn)
| Corn | ||||
| Soybean | ||||
| Corn + soybeans |
Sowing of corn with lupine is carried out by wide-row method with row spacing of 70 cm with standing density of 60-80 thousand plants/ha (seeding rate 30-40 kg/ha). Mixtures of corn with fodder lupine – 40-80 kg/ha or 265-530 thousand plants/ha.
Good results were shown by joint sowing of corn with white fodder lupine at the ratio of corn and lupine 2:4 and seeding of lupine to corn during inter-row tillage.
In the south of Russia joint sowing of corn with sunflower and sorghum is practiced to increase the yield of corn for silage and to improve its technological characteristics.
Mixed crops of corn for silage and sorghum can increase the yield of green mass by 3-5 t/ha and lengthen the silage period by 10-15 days. According to the Erastovsky experimental station (Dnepropetrovsk region, Ukraine), sowing of one row of corn gave 13.5 t/ha of green mass, the joint sowing of two rows of corn and one row of sorghum – 16.0 t/ha.
Thanks to the accumulated experience, the following corn-other-crops mixtures were recommended depending on the zones:
- European part of Russia, Belarus, Ukraine Polesie: corn with fodder lupine, corn with pelushka or vetch, corn with seradella;
- Krasnodar and Stavropol Krais and Rostov Oblast: corn with soybean for silage, corn with pumpkin, corn with zucchini, corn with sorghum, corn with Sudan grass;
- Ukraine and Moldova: maize with beans and soybeans, maize with pumpkin and squash, maize with sorghum and Sudan grass, maize with peas and vetch (in western Ukraine), maize with chickpeas in the steppe;
- Transcaucasia: maize with beans for grain, maize with soybeans for grain and silage, maize with pumpkin.
Seeding of compaction crops is carried out either simultaneously with corn or after the first inter-row cultivation.
Crop care
If necessary, after sowing, rolling is carried out.
In experiments of Chernihiv Agricultural Experimental Station, rolling with water after sowing increased grain yield by 0.95 t/ha with the control yield of 5.04 t/ha. Field germination increased from 71 to 80%. In studies of the Kharkov Agricultural Institute it was shown that unleveled crops lead to a decrease in grain yield by 10-12% (Kuleshov).
To destroy the resulting soil crust and destroy the germinating weeds on the 4-5th day after sowing or 4-5 days before the appearance of seedlings, carry out harrowing, for example, harrows БЗСС-1. The harrow tines should be deepened into the soil by 1-2 cm less than the seeding depth. Harrowing is carried out across the direction of sowing. After the emergence of seedlings, the formed crust is destroyed with rotary hoes.
In the initial period the corn is developing slowly, so there is a risk of weeds smothering its crops by fast-growing weeds. To control them, the crops are harrowed on shoots in the phase of 3-6 leaves, when their sensitive to mechanical damage point of growth is in the soil and protected by tightly folded leaves. Harrowing destroys 70-85% of weed shoots. To reduce damage to corn sprouts during harrowing, a thorough pre-sowing tillage is carried out. Plants often die during initial growth phases because they are pulled out by harrow teeth. During formation of 2-3 leaves plants die because they are covered with soil. At the phase of 5-6 leaves the harrow cannot pull out the plants or cover them with soil.
Harrowing is carried out in the middle of the day with light, medium or rotary hoes with weakened plant turgor for less damage to crops.
In case of good pre-sowing treatment and the use of soil herbicides, carry out 1-2 inter-row treatments. If thinning is necessary, it is carried out in the phase of 3-4 leaves.
On punctuated sowing, 2-3 inter-row treatments are carried out in a timely manner: the first – in the phase of 3-5 leaves, the second – two weeks after the first, the third – when the height of plants 60-70 cm. The depth of cultivation is gradually reduced.
After 6-7 leaves begin to form knot roots, which lie at a depth of 6-8 cm. Damage to the root system of young plants leads to a delay in development. In the zone of sufficient moisture the damaged roots regenerate relatively quickly, while in arid conditions regeneration is slow and the yield decreases. The depth of cultivation and width of the protective zone are set depending on weediness and compaction of soil between the rows, the development of the root system.
During cultivation of inter-row protection zones are simultaneously cultivated by weeding hoes or rotary hoes with needle discs. When loosening, they crumble and level the soil surface, destroy weed vegetation. During the last cultivation, the weeds remaining in the protective zones are covered with a layer of soil, using tines with mouldboards. As a rule, the depth of the first cultivation is 10-12 cm, later reducing it to 4-7 cm. During the first cultivation the width of the protective zones is 10-15 cm, the subsequent ones – 15-25 cm. Weeding harrows allow destroying 80-85% of annual weeds sprouts, rotary needle discs – 70-75%.
Effective arrangement of the cultivator working bodies depending on the location of roots in the soil. In this case the loosening depth increases gradually, with the distance from the row to the center of the row spacing. So, the depth of loosening in the phase of 3-4 leaves at the edges of the row is 6-7 cm, and in the center – 10-12 cm in the phase of 7-8 leaves, respectively, 5-6 cm and 12-14 cm in the phase of 10-12 leaves – 4-5 cm and 7-8 cm respectively.
Herbicides
Common weeds in corn crops include: annual weeds such as field mustard (Sinapis arvensis), shingles (Amaranthus), white vermilion (Chenopodium album), chicken millet (Echinochloa crus-galli), bristlewort (Setaria) and perennial weeds – pink thistle (Cirsium arvense), yellow thistle (Sonchus arvensis), field creeper (Convolvulus arvensis).
Agronomic techniques do not always allow to destroy weeds in the rows. Soil and post-emergent herbicides are used to control them. Highly effective herbicides are an essential element of zonal industrial corn production technologies. Herbicides are selected taking into account the type of weed infestation of fields, zonal features of cultivation, chemical and phytotoxic properties of preparations. Application of chemical control agents allows to reduce the number of cultivations.
Herbicides of soil action used in corn are eradican 6E (4-8 l/ra), agelon (4-6 kg/ha), atrazine (3-8 kg/ha), simazine (1,9-7,5 kg/ha), Prim-Extra* (4-6 kg/ha). Treatment with eradicin 6E is carried out as a spraying with immediate incorporation into the soil. Herbicides are applied taking into account moisture content in the soil layer: in areas with insufficient moisture – during the first or pre-sowing cultivation, in areas with sufficient moisture – in strips before or after (under pre-sowing harrowing) sowing. Atrazine, simazine, agelon, nitazin have negative effect on sensitive crops such as wheat, barley, oats, sunflower for 1-2 years. For this reason, the drugs are used on fields where corn is cultivated in repeated crops 2-3 years in a row or crops resistant to these herbicides, such as millet, sorghum, peas, fodder beans, and potatoes are sown after it.
If weeds cannot be completely suppressed by soil (main) herbicides, and their shoots or sprouts appear in the crops, post-emergent (insurance drugs) are used. The optimal rate of post-emergent herbicides: 2,4-D amine salt – 1.5-2.5 kg/ha, Dialen – 1.9-3 kg/ha, Mayosin (Zeapos-10) – 5.3-13.3 kg/ha, oleogesaprim – 40% mineral-oil suspension – 2-5 kg/ha. They are treated in the phase of 3-6 corn leaves. Mixtures of herbicides are effective due to which the spectrum of exterminating action expands, phytotoxicity in soil decreases and the total consumption of preparations decreases.
When using basic herbicides based on atrazine (agelon, primekstra, mixtures of eradican with atrazine) in corn cultivated in the rotation, post-emergent treatments with insurance herbicides based on oil solution of atrazine (mayazine, oleogesaprim) are not carried out. As this increases their negative effect on sensitive crops. Such fields are treated with 2,4-D amine salt or dialenol.
Diseases
Characteristic diseases of corn are vesicular and dusty mildew, helminthosporiosis, root and stem rot, fusarium, seed and seedling mold, and cob bacteriosis.
Seeds are treated by seed dressing, crop rotation, optimal timing of sowing and harvesting, and fertilization. To prevent the spread of bubbly and powdery mildew, the diseased plants are removed and then destroyed before harvesting.
Main bacterial and fungal pathogens of corn diseases:
- Colletotrichum graminicola (Anthracnose);
- Pseudomonas syringae, other Pseudomonas spp. (Bacterial soft rot);
- Puccinia sorghi (Common rust);
- Ustilago maydis (Common smut);
- Peronosclerospora spp. and Sclerophthora spp;
- Sphacelotheca reiliana (Head smut);
- Exserohilum turcicum (Northern corn leaf blight);
- Pythium and Fusarium spp;
- Bipolaris maydis (Helminthosporium maydis) (Southern corn leaf blight);
- Puccinia polysora (Southern rust);
- Diplodia maydis, Fusarium spp;
- Erwinia stewartii (Stewart’s bacterial wilt);
- Physopella zeae (Angiospora zeae) (Tropical rust);
- Mycosphaerella zea-maydis (Yellow leaf blight).
Southern corn leaf blight during the 1970-1971 epidemic was not a major problem in hybrid sweet corn production because the cytoplasmic male sterility (CMS) used was different from the susceptible form used for other corn hybrids.
Viral diseases:
- Cucumber mosaic virus (CMV);
- Maize chlorotic dwarf virus (MCDV);
- Maize dwarf mosaic virus (MDMV);
- Maize mosaic virus (MMV);
- Maize rough dwarf virus (MRDV);
- Maize streak virus (MSV);
- Sugarcane mosaic virus (SCMV).
Virus-like diseases:
- Corn blunt (Mycoplasma, Corn bush stunt, CBSM);
- Corn stunt (spiroplasma, Corn stunt, CSS);
- Corn wallaby ear (reaction to grasshopper toxin, Maize wallaby ear).
Pests
Characteristic pests of corn include cotton bollworm, winter moth, stem (corn) moth, meadow moth, wireworm, false moth, Swedish fly, bearfly, root and leaf aphids.
Low stem cutting height during harvesting, chopping crop residues and deep autumn plowing are recommended to control stem moths.
Loosening of row spacing during the egg laying period is effective against winter moths.
Chemical control methods are used against wireworms if their number is more than 3-10 units/m2.
Agrotechnical methods are the most effective against Swedish fly, such as sowing at the optimal time, the use of fertilizers. Edge treatments with chemicals are also carried out.
Nematode pests include stem and bulb nematodes (Ditylenchus spp) and spiny nematodes (Paratrichodorus spp). In addition, sweet corn is attacked by species of lesion nematodes, dagger, spear nematode and needle nematode.
Insect pests include the following:
- Spodoptera frugiperda and Pseudaletia unipuncta (Armyworms);
- Blissus leucopterus (Chinch bug);
- Heliothis zea (Corn earworm);
- Rhopalosiphum maidis (Corn leaf aphid);
- Agrotis and Feltia spp;
- Ostrinia nubilalis (European corn borer);
- Systena spp. (Flea beetles);
- Melanoplus spp;
- Diabrotica spp;
- Hylemya platura (Seed corn maggot);
- Tetranychus urticae (Spider mite);
- Papaipema nebris (Stalk borer);
- Lygus lineolaris (Tarnish plant bug);
- Anaphothrips obscurus (Thrips);
- Peridroma saucia (Variegated cutworm);
- Melanotus spp.
Mysin, a flavone glycoside found in corn silk, has antibiotic activity against corn ear larvae; genotypes differ in the content of mysin in the stigmas (silk).
Harvesting
Corn ripens late and irregularly, the cobs are at different heights, and if harvesting is delayed, the plants may bend and droop. Corn in the cob is firmly held, the filling stops when the humidity of the grain is 35-40%.
Corn harvesting begins at the beginning of full maturity, and is completed in 10-12 days. To reduce yield losses due to the extended harvesting time, it is advisable to sow several hybrids with different length of vegetation and maturity dates. This allows for the harvesting of each hybrid in optimal agronomic terms – for 10-12 days for a total harvesting time of 25-30 days.
The following technological schemes of corn harvesting are used:
- special corn harvesters with simultaneous cleaning of the cobs;
- the same corn harvesters with the subsequent cleaning of the cobs by stationary machines ОП-15C, for example, in Polissya, the southern regions of the Central Black Earth zone;
- self-propelled combine harvesters with special devices ППК-4 with the feed to the thresher for threshing only the cobs and simultaneous collection of shredded material. For this method combine harvesters are used, for example, СК-5 “Niva”, “Don-1500” with special attachments.
For harvesting the cobs are used combine harvesters ККП-3 and КСКУ-6, separating the cobs from the stalks and collect chopped leaf and stem mass.
The threshed grain at the latter method of harvesting preserved at moisture above 30% or after processing and drying is put in storage. This harvesting technology is the most rational according to technical and economic indicators. Seed corn is stored for seed purposes on the cob or in grain: the humidity of the cob should not exceed 16%, the humidity of the kernels – no higher than 13%.
The highest yield of dry weight, protein and fat collection is achieved at harvesting in the phase of waxy ripeness of grain. Therefore, it is better to harvest corn for silage in the phase of milk-wax and wax maturity of grain. Vegetative mass and cobs contain a lot of water and sugars, so they are good for silage. In areas where these phases do not come in time, harvesting is conducted before frosts, using forage harvesters and forage harvesters such as КСС-2,6, КСК-100, КСКУ-75, КС-1.8 “Vikhr”, which shred the plant material and load it into vehicles. Corn for green fodder is harvested when useful yield of green mass is reached. Its eatability by cattle decreases after the onset of the phase of flowering of panicles.
After drying till 14-15% corn corns may be kept on the cob or in threshed husked. However, undried corn quickly becomes bitter.
In regions where corn is not fully matured the corn can be used in canned form for feed. To do this, it is chopped into particles 2-3 mm in size at a humidity of 32-35% without drying. The walls of the trench are lined with film, the crushed grain is tramped with heavy tractors, then isolated from air access. The trench is filled and covered in 3-5 days. To grind grain, grinders or crushers are used.
Preservation of pre-shredded corn cobs with corn kernels is also used. The technology of preparation of such corn fodder was introduced in the 80s in the farm “Rossiya” of Shebekinsky district of Belgorod region. The technology made it possible to increase the collection of fodder units by 30-40% from 1 ha and reduce the cost by 35%.
Specifics of cultivation under irrigation
High and stable yields of corn grain and green mass are obtained in conditions of irrigated agriculture. Corn is one of the main fodder crops grown on irrigated plots. Yields can reach 7-10 t/ra of grain and 70-80 t/ha of green mass. According to the averaged for 24 years data of the Kabardino-Balkarian Agricultural Experimental Station, irrigation of corn crops against the background of making mineral fertilizers increased the yield from 3.8 to 7.1 t/ra, against the background of making organic and mineral fertilizers – from 4.0 to 7.41 t/ha.
Wide-row and punctuated methods of sowing contribute to furrow irrigation in the inter-row.
According to the All-Russian Institute of Corn, in the steppe regions of Ukraine, plant water consumption at the same yield reaches 6000 m3/ha. High and thus economically profitable yields are noted when maintaining the moisture of root-containing layer (up to 60-80 cm) at least 70% of the lowest moisture capacity on light soils and not less than 80% on heavy ones due to irrigation. This is achieved by a combination of autumn, winter, spring watering and vegetative irrigation.
According to the data of the Kabardino-Balkarian Agricultural Experimental Station, the efficiency of corn irrigation in the average 7 years was shown in the following experiments:
- without irrigation – grain yield 4.47 t/ha;
- with moisture-recharge irrigation – grain yield of 5.24 t/ha;
- with watering and two vegetation waterings in phases of 6-7 leaves and panicle formation – yield 7.22 t/ha of grain;
- with watering and 3 vegetation waterings in phases of 6-7 leaves, panicle formation and grain filling – yield 7.74 t/ha of grain;
- Irrigations at soil moisture of 80% of the lowest moisture capacity – yield 8.83 t/ha of grain.
Moisture-charge irrigation and precipitation during autumn-winter-spring period should ensure moistening of soil layer up to 1,2-2 m by 90-100% of the lowest moisture capacity. Irrigation norm is 1000-2000 m3/ha. Watering is carried out before or after the plowing, depending on the dryness of the soil. If the soil is not moistened enough due to precipitation and has not been made autumn watering, the pre-sowing watering is carried out. Norm of pre-sowing irrigation is 300-400 m3/hectare of water, if the autumn watering was not carried out, the norm increases to 800-1500 m3/hectare.
Moisture-charge irrigation promotes grain yield increase by 0.6-1.5 t/ha, silage mass increase by 3-12 t/ha.
In some cases, provocative waterings of 250-300 m3/ha are used to provoke the growth of weeds with their subsequent elimination.
The number of vegetative irrigations depends on the amount of precipitation, irrigation rates, irrigation technique, such as furrow irrigation or sprinkling. As a rule, their number is from 2 to 5 at the total irrigation norm of 2000-3000 m3/ha of water. To obtain a high yield of grain and green mass irrigation should be organized in such a way that the plants constantly vegetated under optimal moisture conditions and did not experience even short-term shortages of water. At the same time, temporary overwatering of the soil is undesirable for corn.
It is recommended to determine the timing of irrigation by morphological signs, development phases, soil moisture, physiological indicators and calculations. For example, timing and rates of irrigation are established in phases of 6-7 leaves, 13-14 leaves, hatching, grain formation and ripening, or when soil moisture content decreases below 70-80% of the lowest moisture capacity. Usually both methods produce approximately the same results.
When determining the timing and rates by phase of development, irrigations are set in the periods of greatest sensitivity of corn plants to the lack of moisture in the soil. In the south of Kuban, Central Black Earth zone, forest-steppe zone of the Volga region and Ukraine, where 500-600 mm of precipitation falls during a period, one irrigation is required. Additionally, it is advisable to irrigate during the critical period, i.e. 10-15 days before hatching, 600-800 m3/ha of water. In dry years in these regions and steppe areas of Moldova, Ukraine, Volga, North Caucasus, Transcaucasia and Central Asia with annual rainfall of 300-500 mm spend 2-4 watering with a rate of 600-800 m3 / ha, the first in the phase 6-8 leaves (during the formation of nodular roots, the second – before the release of panicles, the third – during the ripening of grain. If three irrigations are planned, one is given at the phase of 6-8 leaves. In dry years, the fourth irrigation is carried out in the period of milky state of the grain. Schemes can be adjusted depending on weather conditions.
In semi-desert areas with rainfall less than 300 mm per year, the number of irrigations can be increased to 5-7. They are carried out at the beginning and at the end of the growing season in 15-25 days, in the critical period – in 10-15 days.
To determine the timing of irrigation also apply physiological indicators of plants, such as the concentration of cell sap, sucking power, osmotic pressure, the degree of opening of stomata.
Water-physical properties of soil, depth of groundwater occurrence, and irrigation methods are taken into account when setting irrigation rates. On plots with deep groundwater occurrence higher irrigation rates are used – from 800 to 1000 m3/ha of water, with shallow occurrence and use of sprinkling – 400-700 m3/ha.
During the USSR, sprinkling was used on 83% of all irrigated land in Moldova, on 74% of irrigated land in Ukraine, on 40% of irrigated land in the RSFSR. In the south of Ukraine combined irrigations are used: 1-2 irrigations with the norm of 400-500 m3/ha by sprinkling, the subsequent ones – with the norm of 700-800 m3/ha by furrows.
The peculiarity of agrotechnics of corn cultivation under irrigation:
- application of increased doses of fertilizers, primarily nitrogen fertilizers;
- higher density of plants than in rainfed crops;
- effective system of plants protection against weeds;
- use of varieties and hybrids responsive to irrigation;
- loosening of row spacing after irrigation.
Quality requirements for soil treatment on irrigated lands are higher than on non-irrigated ones. For qualitative and effective irrigation the field after plowing should be level, without big piled ridges and deep split furrows.
Under irrigated conditions the limiting factors of yield are only fertilizers and water, so the conditions of getting programmed yields of grain and green mass of corn are formed.
Table. Approximate rates of fertilizer application for corn cultivated under irrigation, with a planned yield of 6-7 t/ha of grain, kg/ha a.s. (All-Russian Institute of Fertilizers and Agrosoil Science)
| Gray earths | |||
| Non-saline meadows | |||
| Meadow saline after washing | |||
| Takyr-like, enriched with mobile nitrogen | |||
| Takyr-like, poor in mobile nitrogen | |||
| Chestnut | |||
| Black earths |
Under irrigated conditions, the use of zoned hybrids and varieties of intensive type responsive to irrigation and fertilization, capable of accumulating at least 3.5-5% of PAR. For example:
- medium-early hybrids – Pioneer 3978M, Kuban 275M;
- middle-ripening hybrids – Krasnodar 440MV, Odessa 59MV, Ossetian 5TV, Stavropol 1MV, Kartuli 9MV;
- mid-late hybrids – Dneprovsky 758TB, Dneprovsky 201, Dneprovsky 85T, Krasnodar 303TB;
- late-ripening hybrids – Krasnodar 229TB, VIR 156TB, VIR 338TB, Chuysky 47, Iveria 503.
Water often limits the yield of green mass of maize in some areas of the Non-Chernozem zone. According to the experience of many farms of Moscow region, in dry periods of vegetation 1-2 sprinkling waterings increase the yield of green mass by 30-40%, reaching 90 t/ha.
Modern corn cultivation technologies
Industrial technology of corn cultivation provides for the comprehensive use of intensive varieties and hybrids, placement of crops on the best predecessors, quality tillage, timely and effective weed control with the use of highly effective fast degradable herbicides, application of optimal doses of fertilizers, work with modern agricultural equipment of high productivity, introduction of progressive forms of organization and labor remuneration, sowing of calibrated seeds The industrial cultivation technology combines certain types of field works, excludes manual weeding, reduces the number of inter-row treatments and the total number of operations, while labor costs for production are reduced by 1.5-2 times.
The Volgograd Agricultural Institute, the Moscow Agricultural Academy, the Southern Research Institute of Hydraulic Engineering and Land Reclamation, the All-Union Research Institute of Corn, the Ukrainian Scientific Research Institute of Irrigated Agriculture and other experienced institutions developed technologies of programmed cultivation of corn, which allow without manual labor to obtain a yield of grain up to 15 tons/ha, green mass – up to 150 tons/ha. These technologies, especially in conditions of irrigated agriculture, allow obtaining stable high yields of corn with good economic indicators.
Resource-saving intensive technology of grain corn cultivation
Experiments conducted by the Department of Agriculture and Crop Production of the State University of Agriculture (Niklyaev V.S., 1995-1998) in the Belgorod region on an area of 130-213 hectares, using resource-saving cultivation technologies, a corn crop of 3.3-4.0 tons was obtained /ha of grain. On an area of 78 ha, the yield was 4.4 t/ha. Corn crops were placed after winter wheat coming after bare fallow. After wheat harvesting, disking was carried out to a depth of 8-10 cm, plowing to a depth of 25-27 cm in compliance with quality requirements. In spring – harrowing of autumn arable land in the state of physical ripeness of the soil, pre-sowing cultivation by 6-8 cm. Such processing contributed to the accumulation and preservation of moisture and nutrients in the soil, improved air conditions, increased soil biogenicity, reduced weedy fields, the number of pests and pathogens . The field prepared for sowing was leveled with a dense seed bed, in the treated layer the content of lumps 1-5 cm in size was at least 80%, there were no lumps larger than 10 cm.
In the experiments, fertilizers were used, which were applied for pre-sowing cultivation at 150 kg/ha and for sowing 80-100 kg/ha of nitrophoska. Organic fertilizers were applied under the predecessor.
The plant protection system included the application of harnes herbicides at a dose of 3 kg/ha during pre-sowing cultivation. In the phase of 3-5 leaves, the treatment was carried out with 2,4-D ammine salt in the amount of 2 kg/ha.
For sowing, we used treated, calibrated seeds of high reproductions, the first class of hybrids Dnepropetrovsk 203MV, BEMO-182, Kulon MV.
Sowing began when the soil warmed up at a depth of seed placement to 10-12 ° C, usually at the end of April – the first decade of May. Sowing was carried out in a short time by the sweat method, in a dotted way with row spacing of 70 cm. The sowing depth was 4-6 cm in a wet layer. The seeding rate is 60-80 thousand/ha of germinating seeds. The estimated standing density is 50-60 thousand/ha of plants.
Crop care consisted of post-emergence harrowing in the phase of 3-5 leaves, 2-3 inter-row treatments, depending on the infestation of crops and soil compaction. The first inter-row cultivation was carried out to a depth of 6-8 cm, the second – 5-6 cm with a deepening to the middle of the inter-row spacing up to 8-10 cm, the third – hilling. KRN-52-53 paws were used for hilling.
Grain harvesting was carried out in the phase of full ripeness with a Don-1500 combine equipped with a KMD-6.
The energy consumption of the given technology per 100 kg of grain is 6-8% less compared to the traditional one (slightly differ by years and hybrids).
Resource-saving intensive technology of cultivation of maize for silage
The resource-saving intensive technology of growing corn for silage was tested in the experiments of the Department of Agriculture and Plant Growing (Niklyaev V.S., 1997-1998) in the Moscow Region on an area of 145 ha and 100 ha, the yield of green mass was 36 t/ha and 40 t / ha. The nutritional value was 0.24 and 0.26 feed units, the collection of crude protein was 720 kg/ha and 800 kg/ha.
This technology is based on rational methods of tillage, sowing of early-ripening and mid-early hybrids, optimal rates of fertilizer and herbicide application, improvement of the territorial structure of fodder production, advanced training of specialists.
Technology system:
- manure application once every 4-5 years at 40-50 t/ha;
- autumn plowing to a depth of 20-22 cm;
- closing moisture in early spring and leveling the soil surface;
- cultivation to a depth of 14-16 cm;
- application of 200 kg/ha of ammonium nitrate and potassium chloride for presowing cultivation;
- pre-sowing cultivation to a depth of 8-10 cm;
- sowing in a wide-row-dotted method at the optimal time (before May 15), seeding depth 5-6 cm, seeding rate for early-ripening hybrids 110-120 thousand/ha of germinating seeds, mid-early – 90-100 thousand/ha of germinating seeds;
- row application when sowing 100 kg/ha of nitrophoska;
- introduction at crops of herbicide harness 3 kg/ha or eradican 8 l/ha;
- processing in the phase of 3-5 leaves with herbicide dialen 2 kg/ha;
- pre-emergence harrowing;
- in the phase of 8-10 leaves – inter-row cultivation to a depth of 6-8 cm with simultaneous application of 80 kg/ha of ammonium nitrate;
- harvesting in a group driven way in late August-early September in the phase of milky-wax and wax ripeness. Early ripe hybrids are harvested first, cutting height is not more than 10-12 cm;
- laying green mass in trenches within a period of not more than 3-4 days with compaction;
- covering the compacted mass with polyethylene film and soil.
Early ripe hybrids Nart 170 SV, Bemo 182 SV. Mid-early – Collective 244 MB.
The reduction in energy costs when using resource-saving technology for growing corn for silage compared to the traditional one was 10-12.5%.
Astrakhan technology
The Astrakhan irrigation technology developed for vegetable crops has proven itself well. It consists in cutting guide slots before sowing, along which special knives move during sowing and inter-row cultivation, preventing the units from shifting. This allows you to work at higher speeds, reduce the cutting of corn plants. Simultaneously with the cutting of cracks, herbicides can be applied in rows.
The use of hybrid seeds and methods of their cultivation
The use of the best zoned hybrids of the first generation and varieties with high sowing and yielding qualities for sowing is a prerequisite for obtaining high yields of grain and silage in all areas of cultivation.
Standard procedure for the production of corn seeds. Research institutions grow elite seeds from the original parent forms of released hybrids, released varieties and hybrid populations. From elite seeds, special seed farms grow hybrid seeds of the first generation and propagate seeds of varieties and hybrid populations. The resulting seeds are prepared for sowing: the cobs are threshed, the seeds are cleaned, calibrated, treated, packaged in paper bags and stored until they are sold in seed storage facilities.
Hybrid seeds of the first generation are obtained from hybridization plots. Selected parental forms are sown in alternating rows in isolated areas. If the mother form does not have cytoplasmic male sterility, panicles are cut off before flowering. As a result, pollination of cobs of plants of the maternal form occurs only with the pollen of paternal plants, forming hybrid seeds of the first generation. Grain from plants of the paternal form is usually used for fodder. The whole range of agricultural practices is provided for seed crops of corn, which determines the receipt of a good harvest of high-quality seeds. In arid and semi-arid areas, irrigation should be used.
On seed crops, the whole complex of agricultural practices is provided, which determines the receipt of a good crop of high quality seeds. Irrigation is used in arid and semi-arid conditions.
Sources
Crop production / P.P. Vavilov, V.V. Gritsenko, V.S. Kuznetsov and others; Ed. P.P. Vavilov. – 5th ed., revised. and additional – M.: Agropromizdat, 1986. – 512 p.: ill. – (Textbook and textbooks for higher educational institutions).
V.V. Kolomeichenko. Crop production / Textbook. — M.: Agrobusinesscenter, 2007. — 600 p. ISBN 978-5-902792-11-6.
Fundamentals of agricultural production technology. Agriculture and crop production. Ed. V.S. Niklyaev. – M .: “Epic”, 2000. – 555 p.
World vegetables: principles, production, and nutritive values / Vincent E. Rubatzky and Mas Yamaguchi. — 2nd ed. 1997.