Rapeseed (Brassica napus L. ssp. oleifera) is a promising food and fodder oilseed crop, also belongs to the technical row crops of crop rotation.
Source: flickr.com©Harry Rose (CC BY 2.0)
Economic importance
As of 1986, rapeseed was considered the main oilseed crop in 28 countries around the world.
Rape seeds contain 32 to 50% oil and up to 23% protein. Of all the oilseeds of the cabbage family, winter rape ranks first in terms of oil content in seeds (45-50%). In addition, the seeds of winter forms contain up to 20% protein and 17% carbohydrates. Semi-drying rapeseed oil can be used for food and technical purposes (iodine value 94-112).
In the seeds of spring rape, the oil content is 35-45%, protein – 21%, carbohydrates – 17-18%. The oil is slightly drying, used for food and technical purposes.
The seeds of old varieties of rapeseed contained a large amount of erucic acid (37-50%) and glycosinolates (5-7%) harmful to animals, which gave the meal a bitter taste and negatively affected the thyroid gland, especially in birds and pigs. At present, varieties with a low content of erucic acid (0-5%) and glucosinolates (0.3-0.6%) have been bred, while the content of oleic acid has been increased to 60-70%. The content of linolenic acid is 10-13%.
Rapeseed oil is important in the food, soap, printing and other industries.
The yield of cakes (meal) from seeds is 56%, and the protein content in them reaches 38-40% (Vavilov; according to other sources, up to 45-49%, Kolomeichenko), which is well balanced in terms of amino acid composition. Cake and meal of non-eruk varieties serve as good food. Meal from the seeds of ordinary varieties of rapeseed contains 6-7% glycosinolates, while non-erucic – less than 0.5%, and therefore can be compared with soybeans. Cake and meal from seeds of ordinary varieties can be fed to animals, but in small quantities. 100 kg of cake correspond to 100 feed units.
Rapeseed can be used in intermediate and post-harvest crops for the production of fodder – green mass, silage, haylage, grass meal. 100 kg of green mass correspond to (11) 16 feed units and contain 30 g of protein or 190 g (Vavilov; according to other sources, 120-140 g of digestible protein, Kolomeichenko) and 140-150 g of sugar per 1 feed unit. The green mass of winter cabbage crops is distinguished by high fodder qualities, contains a large amount of protein and mineral salts, but little fiber. The chemical composition of dry matter: crude protein 15-20%, fats 4%, fiber 14-16%. The content in 1 kg of green mass of carotene is 60-95 mg. In terms of amino acid composition, it surpasses winter cereals and is not inferior to clover and alfalfa. The eatability of green mass by agricultural animals reaches 93%, and organic matter is characterized by high digestibility (70-80%). The disadvantage is the low content of dry matter (9-11%). Feeding green mass increases the productivity and fat content of milk.
In terms of green mass formation in early spring, winter rapeseed exceeds winter rye. It also regrows intensively after cutting and has versatility of use. For fodder, winter rape can be used as a spring crop, while after sowing in the spring it grows rapidly, but does not bloom, and with sufficient moisture in the conditions of the forest-steppe zone, it can produce 2-3 cuttings. For multi-cutting use (3-4 times), winter rapeseed, due to the possibility of growing from axillary buds and meristem tissue of the stem, is 20-30% more productive than winter rapeseed and perko.
Rape is of great importance in intermediate crops (winter, early spring, hay and stubble crops). When sown in autumn, green fodder can be obtained already in early May (after 30-40 days, for seeds – after 60-80 days), and after harvesting in forest-steppe conditions, almost any annual fodder crops can be cultivated. However, the largest yields at such sowing dates are heat-loving crops such as corn, sorghum, sorghum-sudanese hybrids, sudan grass, mogar, paiza, millet, chumiza and sunflowers alone or mixed with high protein plants or fodder cabbages, kohlrabi and rutabagawhen planting seedlings.
In spring forms of rapeseed, mowing ripeness occurs 60-70 days after the beginning of the growing season.
When growing winter rapeseed in a busy fallow, it is advisable to sow a vetch-oat mixture to it in spring. Thus, it is possible to additionally obtain two crops of green mass (the first – due to rapeseed or Barbarea, the second – due to the vetch-oat mixture). At the same time, there is enough time for a good preparation of the field for sowing winter crops.
Winter rapeseed for green fodder is especially valuable for feeding pigs and fattening cattle. In the green conveyor system, it is more expedient to feed it in early spring and late autumn, when other green fodder is scarce. In late autumn, it can be both mowed and bled, thus increasing the grazing period by a month.
Winter rapeseed in its pure form is well ensiled, but can also be used to make silage with good quality straw or dried grass in a chopped form, or added to corn, sorghum, sunflower and other crops silage to increase nutritional value. Rapeseed silage contains: 87.3% water; 2.4% protein; 0.1% fat; 1.3% fiber; 2.7% ash and 5.0% nitrogen-free extractives; 1.9 mg/kg carotene. Digestibility coefficients: protein and fat – 72%; fiber – 53%; nitrogen-free extractives – 75%.
Winter rapeseed is of great agrotechnical importance in crop rotations. It improves the physical properties and phytosanitary condition of the soil. Due to its fast growth and highly developed above-ground phytomass, rapeseed is good at suppressing weeds.
Good honey plant. The collection of honey from rapeseed reaches 100 kg/ha.
Rapeseed can be used as a green manure.
Rapeseed is widely used for biofuel production.
Crop history
Rapeseed originates from the Mediterranean region, from where it came to India and other Asian Asias.
Rape was introduced into the culture more than 4000 years ago.
In Europe, it became widespread as an agricultural crop in the 16th century.
In Russia, rapeseed began to be cultivated in the 18th century.
Cultivation areas and yield
The area under rapeseed in the world in 1986 was more than 13 million hectares. Its main producers were India (3.9 million ha), China (3.7 million ha), Canada (3.0 million ha). Significant areas were in Germany, Poland, Sweden, France, Finland.
By the end of the 20th century, the area under rapeseed (including Barbarea) amounted to 24 million hectares, or 13% of the total sown area of all oilseeds. The total gross harvest amounted to 34 million tons, or 12% of the total production of oilseeds. Productivity is 1.5 t/ha.
Under good wintering conditions, winter rapeseed usually yields more than spring rapeseed.
In Canada, rapeseed is one of the most highly profitable crops due to the development and use of non-erucic varieties with a low content of glucosinolates. The growth of profitability was facilitated by the transition of production and processing of rapeseed to an industrial basis.
In the USSR in 1982, the sown area of rapeseed grown for seeds was 68,000 ha. For commercial purposes, winter rapeseed was grown. The main sown areas were concentrated in Western Ukraine. The yield of seeds is 1.5-1.8 t/ha.
In 2001-2005 200 thousand hectares or 4% of the total sown area of oilseeds were occupied under rapeseed and colza in Russia. The gross harvest of seeds amounted to 200 thousand tons.
The yield is 1.2-1.6 t/ha for spring, 1.5-2.9 t/ha for winter. When using industrial growing technology, in compliance with the whole complex of technological methods and factors, using modern intensive non-erucic and low glucosinolate varieties, plant protection products, the yield of winter rapeseed seeds can reach 3.0-3.5 t/ha, spring – 2.0- 2.5 t/ha. So in the collective farm “Borets” (Ramensky district of the Moscow region, 1982) a crop of spring rapeseed seeds was obtained 2.9 t/ha.
In Russia, at present, winter rapeseed is cultivated only in the North-West, in the Central Black Earth zone, and in the North Caucasus, where sharp temperature fluctuations are not typical in winter and early spring.
For fodder purposes, rapeseed is grown in Eastern and Western Siberia, in the Central Black Earth and Non-Chernozem zones of Russia, as well as in the north of Kazakhstan, Ukraine, and the Baltic countries.
The yield of winter rapeseed for green mass is 25-40 t/ha. In post-cutting crops after annual grasses, under conditions of wet and cool weather in the second half of summer, the yield of winter rapeseed can reach 30-40 t/ha. Rapeseed does not tolerate hot dry weather well, while the susceptibility to diseases and pests increases.
In stubble crops after harvesting peas, winter and spring cereals for grain, the yield of green mass reaches 15-20 t/ha.
Botanical description
Rapeseed (Brassica napus L. ssp. oleifera Metzg. (winter – biennis , spring – annua)) belongs to annual herbaceous plants of the Brassicaceae family.
The tap root, developed, slightly branched, penetrates the soil to a depth of 1.5-2 (3) m.
The stem is erect, strongly branched, covered with a thick wax coating, gray, pubescent below.
Plant height 100-130 (170) cm.
The leaves are gray-green, also have a waxy coating. The form is different. The lower leaves are lyre-pinnately incised, on petioles. Medium – elongated spear-shaped. The upper ones are elongated-lanceolate, sessile, half covering the stem.
The inflorescence is a loose brush. The flowers are light yellow or golden yellow, large.
The fruit is a pod that cracks when ripe, narrow, smooth, with a spout 1/5-1/6 of the length of the pod.
The seeds are spherical, the surface is finely cellular, black, grayish black or dark brown. Diameter 1.5-2 mm. The weight of 1000 seeds of winter rapeseed is 3-7 g, of spring rapeseed – 2.6-5.0 g.
Biological features
Rapeseed is a long day plant.
Rape seeds begin to germinate at a temperature of (1) 2-3 °C.
Seedlings are able to withstand frosts of -3 … -5 ° С. Plants continue growing even at temperatures of +2…+3 °C and tolerate autumn frosts down to -8 °C. Winter rapeseed can withstand temperatures down to -8…-10 °С.
The optimum temperature for the growth of the vegetative mass is 18-20 °C, during flowering and seed ripening – 23-25 °C.
The growth point of winter rapeseed plants is at a height of 2-6 cm.
Rapeseed is a moisture-demanding crop, during the growing season it consumes 1.5-2.0 times more water than winter wheat. The transpiration coefficient is 500-700. Sufficient moisture is especially important during the flowering and seeding phases.
Able to grow on all types of soils, except for heavy clay, sandy (due to low water-holding capacity) and waterlogged. It reacts badly to increased soil acidity.
Winter forms usually hibernate well if there is sufficient snow cover, that is, more than 15 cm. According to long-term observations of the All-Union Research Institute of Feeds, in the conditions of the central regions of the Non-Chernozem Zone of Russia, winter rapeseed does not die in winter, but in spring from sudden temperature changes, when the snow cover has already melted.
Sowing winter forms of rapeseed in autumn and hardening in autumn provide high winter hardiness of modern varieties.
Spring rapeseed is considered less demanding on soil and climatic conditions, therefore it has become more widespread in Russia.
Vegetation
Rape has winter and spring forms.
The duration from germination to ripening in spring rapeseed is 95-110 days, in winter rapeseed – 290-320 days.
Spring vegetation in winter forms begins when the average daily temperature is about 2 °C. Two weeks after the start of the growing season, the phase of stemming and budding begins. Flowering lasts 25-30 days, and 25-30 days pass from the end of flowering to ripening.
With warm and moist soil, the seeds germinate in 4-5 days.
The duration of the period for spring forms from germination to the formation of a rosette is 20-30 days, to stalking – 30-40 days, after which the vegetative mass begins to grow rapidly. Until flowering – 35-50 days, flowering lasts 20-35 days.
Winter rapeseed forms a rosette of 5-9 leaves in autumn, and the stem begins to develop in the spring of the following year.
Development phases of winter rapeseed:
- seedlings;
- rosette formation (6-8 leaves);
- shooting;
- bloom;
- pod formation;
- milky state of seeds;
- wax ripeness;
- full ripeness.
Crop rotation
The technology of rapeseed cultivation requires taking into account its biological characteristics: small seed, slow growth and development in the initial phase of development, high requirements for nutrients and soil fertility.
The best predecessors of winter rapeseed when grown for seeds are black and busy fallows, silage crops, perennial grasses, annual grasses for green fodder, in addition to Sudanese grass, in the North Caucasus – also cereal crops. Return to its original place in the crop rotation is possible not earlier than after 4 years (for spring – after 4-5 years). Cruciferous crops and fields infested with weeds from the cruciferous family ( Brassicaceae) are poor precursors . The placement of winter rapeseed in sugar beet crop rotations should also be avoided due to the danger of nematode breeding.
The best predecessors in the cultivation of winter rapeseed for green fodder are the layer or turnover of the layer of perennial grasses, legumes, tilled, winter and spring crops
In post-cutting crops, winter rapeseed is placed after annual grasses, early potatoes and other crops. In stubble – after peas, winter and early spring cereals.
The best predecessors of spring rapeseed are grain crops coming after fallow, as well as tilled crops , perennial grass layer turnover, black fallow, leguminous crops , cereal-bean mixtures for green fodder. It is not recommended to alternate spring rapeseed with sunflower, clover, sugar beet and millet in crop rotation.
In crop rotations, rapeseed performs a phytosanitary function. Thanks to the deep penetrating root system of winter rapeseed (up to 3 m), the soil structure improves and its fertility increases.
Winter rapeseed can serve as a good predecessor for winter and spring cereals, corn and other crops.
Fertilizer system
Rapeseed is a crop demanding on soil fertility.
For the formation of 100 kg of seeds, rapeseed consumes 1.5-2 times more nutrients than cereals or annual grasses.
The approximate removal of nutrients from the soil from 100 kg of seed yield is: N – 5-6 kg; P2O5 – 2.4-3.5 kg; K2O – 4.0-6.0 kg; CaO – 4-7 kg, MgO – 1.4-2.2 kg, sulfur – 4.0 kg. Separately, for spring rapeseed: N – 5.4-6.2 kg; P2O5 – 2.4-3.4 kg; K2O – 9.4 kg; CaO – 11.6 kg.
Rape responds well to the application of fertilizers, primarily nitrogen and potassium. According to the data of the All-Union Research Institute of Forage, when grown for green mass, rapeseed uses: N – 2.6 kg, P2O5 – 0.91 kg, K2O – 3.9 kg to form 100 kg of dry matter.
Under a fallow-occupying crop (any predecessor) or fallow, it is recommended to apply 20-30 t/ha of manure.
In the conditions of the North Caucasus, to obtain high yields of seeds, N90-120P60-90K60-90 is applied for plowing. For the Nonchernozem zone, it is recommended to apply for plowing at 90 kg/ha of a.i. potash and phosphate fertilizers, for pre-sowing cultivation (30) 40-50 kg/ha a.i. nitrogen and in early spring in top dressing 60-90 kg/ha (All-Russian Research Institute of Fodder). In general, it is recommended to apply N45P60K90 for the main treatment.
Early spring top dressing is also recommended to be divided into two: the first is carried out on frozen and thawed soil, the second – in 2-3 weeks.
Fractional nitrogen fertilization increases the protein content, but slightly reduces the fat content of the seeds. Any nitrogen fertilizers are suitable for nitrogen fertilizing, but ammonium sulfate is more effective, as it additionally contains sulfur, to which winter rapeseed responds well.
When sowing, it is recommended to apply phosphorus P10-20 to the rows .
Phosphorus promotes the development of the root system, increases the productivity of seeds and accelerates their maturation.
It is advisable to calculate the fertilizer application rates for the planned harvest, taking into account soil fertility and the removal of nutrients with the harvest.
When growing rapeseed for green fodder, after the first mowing, it is advisable to fertilize with nitrogen fertilizers with a consumption rate of 60 kg/ha of a.i.
Liming is carried out on acidic soils.
Sulfur fertilizers are also recommended for forest and sandy soils.
Tillage system
Soil cultivation for winter rapeseed includes peeling, plowing and subsequent semi-fallow cultivation. After non-steam predecessors, plowing is carried out with plows with skimmers of 20-22 cm with simultaneous harrowing.
The main tillage for spring rapeseed is similar to that for early spring cereals. In the steppe zone of Russia, it is recommended to carry out methods of accumulation of moisture in winter (snow retention). In the case of using flat-cut tillage, which preserves the stubble before winter, herbicides should be applied in spring before sowing spring rapeseed. Pre-sowing treatment should ensure the preservation of the moisture of the upper soil layer and the evenness of the surface.
In the tillage system, it is important to pay attention to leveling and cutting the soil, as this is a small-seeded crop. The roughness of the soil surface leads to variegation of the stem, wetting, loss of seed yield during harvesting.
Before sowing, the leveling of the soil surface is carried out by cultivators in an aggregate with harrows, trains and rollers. The depth of pre-sowing treatment is 4-5 cm.
With early spring sowing, tillage is carried out in the same way as for other small-seeded crops.
In the spring, before sowing spring rapeseed, two-track harrowing is done with toothed harrows (during autumn plowing) or needle harrows (during flat-cutting). Combined units are more efficient. For this purpose, it is also possible to use beet cultivators with flat-cutting working bodies, harrows and trains. The depth of pre-sowing cultivation, depending on soil moisture, reaches 5-7 cm. After that, it is advisable to roll dry soil with ringed rollers. Under presowing cultivation, if necessary, soil herbicides are applied.
Sowing
Sowing of winter rape starts 2-3 weeks earlier than winter crops, so that the plants can form a powerful rosette of leaves, deeply penetrating the root system and undergo hardening.
Sowing of spring rapeseed is started simultaneously with early spring crops. However, in weedy fields, sowing can be started a little later (after the destruction of weed seedlings using pre-sowing cultivation).
The method of sowing spring and winter rapeseed is the usual ordinary and wide-row with row spacing of 30 or 45 cm. Grain or grain-grass seeders are used for sowing. If necessary, preliminary and / or post-sowing packing is carried out.
The seeding rate (spring and winter) for the usual row sowing method is 12-15 kg/ha (also separately, for spring rapeseed the recommended seeding rate is 9-12 kg/ha), for wide-row sowing – 6-8 kg/ha (also separately , for spring rapeseed the recommended seeding rate is 7-8 kg/ha).
The depth of sowing seeds of winter rapeseed is 2-3 cm (on heavy soils 1.5-2 cm, on light soils – 3 cm), in case of drying of the upper soil layer, it is increased to (3) 4-5 cm. The sowing depth of spring rapeseed seeds is 3-4 cm.
After sowing, it is recommended to carry out packing using ringed rollers.
When growing winter rapeseed for green mass, it is sown in early spring, simultaneously with the sowing of early spring crops.
When using winter rapeseed for the green conveyor, it can be sown in August (for the forest-steppe zone – from July 25 to August 5). However, earlier dates in mowing or stubble crops (II-III decade of July) allows you to get a slightly larger yield than sowing in the first decade of August. The seeding rate is 2.5 million viable seeds per 1 ha, or 12-15 kg/ha. The choice of optimal sowing dates determines the resistance of plants to overwintering conditions. To do this, the plants must go before winter, forming a rosette of 6-8 leaves. To improve overwintering conditions, it is desirable to create wings of white mustard, the seeds of which are mixed with winter rape seeds at the rate of 1-1.5 kg/ha.
Winter rapeseed for green fodder can be grown using technology with undersown crops. In this case, it is sown, as usual, in the fall, and early in the spring a mixture of common vetch, oats and annual ryegrass is sown to it. Seeding rates in this case are 120 kg/ha, 100 kg/ha and 25-30 kg/ha. Sowing is carried out with disc seeders across the rows of winter rapeseed. Sowing depth on heavy soils is 3-4 cm, on light soils – 5-6 cm.
Winter rapeseed can be sown in crops mixed with other crops, such as oats, peas, sunflowers, oilseed radish, white mustard. Recommended seeding rates: rapeseed (5-6 kg/ha), oilseed radish or white mustard (20-25 kg/ha), oats (100-130 kg/ha), sunflower (10-15 kg/ha), peas ( 90-100 kg/ha). In this case, a mixture of peas, oats and sunflower is first sown, then the soil is rolled and a mixture of winter and spring cabbage crops is sown.
In stubble crops (in the first decade of August), winter rapeseed is sown separately or mixed with other crops of the same family. The seeding rate is 2.5 million viable seeds or 12-15 kg/ha.
Crop care
In autumn, after sowing, in case of formation of a soil crust, pre-emergence harrowing is carried out. If necessary, rolling is also carried out after sowing.
When the winter rapeseed plants reach the 4-6 leaf stage, it is desirable to carry out autumn harrowing using light or medium tooth harrows at a machine speed of 4-5 km/h. On seed wide-row crops of winter rapeseed, inter-row cultivation begins with the formation of the second pair of leaves. If necessary, a second cultivation can be carried out before the rows close.
Winter activities in winter rape crops should be aimed at protecting plants from freezing, ice crust formation and soaking. After the beginning of the spring growing season, top dressing is carried out and then harrowing across the rows. On wide-row crops of winter rapeseed, inter-row cultivation is also carried out.
In crops of spring rapeseed in the phase of 4-5 true leaves, weeds are destroyed by seedlings using tooth harrows in the afternoon. On wide-row crops, inter-row cultivation is carried out 2-3 times to a depth of 5-6 and 6-8 cm. To protect young plants from sprinkling with soil, special devices are used.
To combat weeds, you can use the herbicide treflan 25% with a consumption rate of 2.5-3 l/ha for pre-sowing cultivation.
To control weeds, it is desirable to give preference to agricultural practices.
An effective method of control in crops of winter rapeseed for green fodder is mowing weeds at a height of 10-12 cm a month after the emergence of rapeseed seedlings. After mowing, rapeseed grows quickly, forms powerful leaves and further suppresses weeds.
Plant protection
To control pests in rape crops, spraying with metaphos 0.2-0.3 kg/ha a.i. is used. Treatment in the flowering phase of rapeseed is not carried out so as not to cause the death of bees.
The main diseases of rapeseed are downy mildew, alternariosis, powdery mildew.
Harvest
Winter rape is characterized by an extended period of seed ripening, and the pods are easily cracked. Therefore, delaying the optimal harvesting time leads to seed losses. However, premature harvesting also results in poor quality, puny seeds and yield loss.
Harvesting is carried out in one phase, at the onset of full ripeness, using grain harvesters adjusted for harvesting small-seeded crops. The single-phase method is more appropriate in the absence of weeds and seed moisture content of at least 18%.
In dry weather, it is better to use a two-phase cleaning method. To do this, the plants are mowed into rolls when the lower leaves fall off, and about half of the pods on the plants become lemon yellow with a seed moisture content of 30-40%, and the seeds in them become brown and black. The windrows are threshed as they dry out at a seed moisture content of 10-11% (approximately 4-7 days after mowing), and if the autumn is wet – no more than 20% with immediate cleaning and drying to a moisture content of 10-12%. In hot and dry weather, windrow threshing should be carried out in the morning, evening or at night, in this case, seed losses are reduced and their crushing is reduced.
Cleaned seeds should be stored for storage at a moisture content of no more than 8%.
When growing rapeseed for green fodder with two cuttings, the first cutting is carried out after 50-60 days from emergence, when the height of the plants is 50-60 cm, at the cutting height – 10-12 cm. The second cutting is carried out after (45) 48-50 days after the first, at a height of 5-8 cm. With three-cut use, the first cut is carried out after 35-45 days from emergence, with a plant height of 30 cm. The second cut is 35-50 days after the first, the third – after 50-60 days after the second (or used for grazing). After the first and second, it is desirable to fertilize with nitrogen fertilizers 3-4 days after mowing. Three-legged use is advisable only if there is sufficient moisture, therefore, in the steppe zone, this is possible only under irrigation conditions.
Mowing for green fodder is carried out by any forage harvester. Since rapeseed is a good honey plant, harvesting during the flowering phase should be done early in the morning and late in the evening to protect the bees.
When growing winter rapeseed for green fodder using technology with subsowing crops (sowing vetch, oats, annual ryegrass), with sufficient moisture and nutrient supply, it can produce 3-4 cuts with a total yield of 60-70 t/ha of green mass. In this case, the first cut consists of winter rapeseed, which is harvested in the budding phase – the beginning of flowering at a cut height of 10-12 cm. The second mowing is carried out in the phase of mass flowering of the sowing vetch at a height of 6-8 cm. The third and fourth cuttings include mainly annual ryegrass, they are carried out at the beginning of the heading of ryegrass. The fourth cut (otava) is suitable for grazing. This technology makes it possible to confine oneself to two cuttings (excluding ryegrass), and then to prepare the field for sowing winter cereals. In this case, a busy fallow is obtained, the productivity of which is 1.5 times greater than the usual sowing of vetch-oat or pea-oat mixture.
For harvesting for silage, rapeseed is best used in unground form. To reduce the moisture content of raw materials, 1 part of chopped straw is added to 3-5 parts of green mass (by dry matter).
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.