Alfalfa
Alfalfa (Medicago sativa).
Alfalfa — a forage agricultural crop belonging to perennial leguminous grasses.
Economic importance
Alfalfa hay is distinguished by high forage qualities; in this indicator it ranks first among forage crops, contains a large amount of protein, phosphorus, calcium, essential amino acids. 100 kg of alfalfa hay corresponds to 50.2 feed units and contains 13.7 kg of digestible protein (VNII of Feed).
Alfalfa is used for forage purposes in green form or for harvesting feed (hay, haylage, grass meal). 100 kg of fresh grass harvested in the flowering phase corresponds to 21.3 feed units and contains 4 kg of digestible protein (VNII of Feed).
The chemical composition of alfalfa haylage with a moisture content of 48%, calculated on an absolutely dry matter basis, includes: 15.9% protein, 23.5% fiber, 3.2% fat, 8.2% ash substances, 49.2% NFE, 2.2% calcium, 0.3% phosphorus.
100 kg of grass meal corresponds to 85 feed units, contains 10-14 kg of digestible protein and 25-30 g of carotene.
When grown without irrigation, alfalfa is cut 2-3 times per summer; under irrigation, 4-5 times. Compared with clover, alfalfa in sowings is more long-lived, capable of growing in the steppe zone for 3-4 years, in the forest-steppe for 5-6 years. Maximum yield occurs in the 3rd-1st year of plant life.
Thanks to its powerful root system, it grows and gives good hay yields in steppe areas with an arid climate, promotes enrichment of the soil with nitrogen and organic matter, accumulating over two years 200-300 kg of nitrogen and 8-10 t of root and crop residues in terms of dry matter. Three-year-old plants are capable of accumulating in the soil nitrogen corresponding to the application of 60-70 t of manure.
The alfalfa sod serves as an excellent predecessor for spring durum wheat, rice, millet and especially cotton and other crops. Alfalfa-cotton crop rotations provide high cotton yields with high fiber quality, improving soils against fungal infection — cotton wilt. Alfalfa promotes soil desalinization.
It also grows well in the Non-Chernozem zone provided liming of soils and groundwater occurrence deeper than 2 m.
Alfalfa is an important component of grass mixtures of irrigated cultivated pastures in the steppe and dry-steppe zones, as well as in Central Asia and Transcaucasia.
It can also be used for livestock grazing, however, with early, low and frequent grazing it drops out of the herbage. For grazing pigs and poultry, pure alfalfa sowings are suitable; for cattle, grass mixtures, since in pure form it can cause tympany (bloat) in animals.
In grass mixtures it is used together with awnless brome, crested wheatgrass and other cereal grasses. Mixtures overwinter better and are less thinned, yields are more stable, resistant to pests and weeds.
History of the crop
Alfalfa is one of the oldest agricultural crops. Presumably, its cultivation began simultaneously with wheat.
Cultivation areas
Alfalfa is widely grown in the south and southeast of Russia, in the steppe and forest-steppe zones, central regions of the Non-Chernozem zone, Belarus and the Baltic countries.
The largest sown areas are concentrated in the Central Chernozem zone, North Caucasus and Volga region.
Yield
The hay yield of alfalfa reaches 12-20 t/ha, usually 4-6 t/ha. Yield strongly depends on moisture conditions. In dry years the yield can decrease to 1.5-2 t/ha; under irrigation it can increase to 12 t/ha.
The seed yield of alfalfa is 150-200 kg/ha, maximum up to 500-800 kg/ha.
Botanical description
Species
Alfalfa includes more than 100 species; in Russia and the countries of the former USSR there are 36 annual and perennial alfalfa species, of which the most widespread is alfalfa, or blue alfalfa — Medicago sativa L. Also used in production are yellow, or sickle, alfalfa (Medicago falcata L.) and variable, or hybrid, alfalfa (Medicago varia). Sometimes northern alfalfa (Medicago borealis Grossh.), blue alfalfa (Medicago coerulea Less.), and black medick are mentioned.
Varieties of variable alfalfa are divided into blue-hybrid, variegated-hybrid and yellow-hybrid, and sometimes blue-variegated-hybrid are also distinguished (VNII of Feed). The blue-hybrid group of varieties is cultivated mainly in the south of the country; it is distinguished by the ratio of violet (85-95%) and light-violet, almost white (5-15%) corolla color. The variegated-hybrid group has 50-65% violet corollas and 35-50% yellow. The yellow-hybrid group of varieties has 20-55% violet flowers and 45-80% yellow.
In field crop rotations of the steppe and forest-steppe zones, as well as on irrigated lands, it is recommended to use blue, blue-hybrid or variegated-hybrid alfalfa; for sowing down slope lands — yellow-hybrid and yellow; in floodplains — variegated-hybrid, yellow-hybrid and yellow varieties of alfalfa.
Alfalfa
Root system
The root is taproot with well-developed lateral roots. In the first year of plant life, roots penetrate to a depth of 2-3 m; in subsequent years, up to 10 m. About half of the root system mass is located in the arable soil layer.
The powerful root system allows alfalfa to accumulate a large amount of root residues in the soil. Under irrigated farming in Central Asia, alfalfa serves as the main source of organic mass for humus formation.
In the upper part of the root is the root crown, or crown, formed from the hypocotyl and is an overgrown part of the main stem. Buds are formed in the root crown, from which new stems develop. With age, the crown deepens into the soil, sometimes going to a depth of 7-10 cm, thereby protecting plants from cold in snowless winters.
Nodules develop on alfalfa roots, causing the ability for nitrogen fixation. Under irrigation conditions in Central Asia, three-year-old alfalfa plants are capable of accumulating 300-400 kg/ha of nitrogen.
In the Non-Chernozem zone, roots can reach a depth of 3 m. Usually they cannot penetrate through the podzolic horizon, therefore they are located mainly in the arable layer. This feature is taken into account when choosing a field for sowing alfalfa and the method of soil tillage, which should include plowing with subsoiling. At the first sowing in a crop rotation field, seeds are treated with bacterial preparations, for example, nitragin or rhizotorfin; otherwise nodules do not form on the roots, and plants die in the 2nd-3rd year of life.
Aboveground part
The stem is herbaceous, strongly branching, green, in the lower part sometimes with anthocyanin. The stem has 10-20 internodes. In the first year of life, one alfalfa plant forms 3 stems; in the second year, 15-17; in the third, more than 20. Plant height in the first year is 30-50 cm; in the 2nd-3rd, more than 1 m. Leaves account for 50% of the aboveground mass in the first year, and about 40% in the 2nd-3rd.
The leaf consists of a stipule, petiole and three leaflets, set on short stalks, serrated in the upper part. The color is light green and dark green.
The inflorescence is a many-flowered raceme, 1.5-8 cm long, cylindrical or capitate. The flowers are papilionaceous, bisexual, located on short pedicels, at the base of which there are two filiform bracts. The flower includes a calyx, corolla, stamens and pistil. The calyx is green, five-toothed. The structure of the flower corolla is similar to that of clover. The number of stamens is 10; 9 fuse forming a staminal tube. The corolla is bright violet or light violet. Pollination is cross.
The fruit is a many-seeded pod, yellow, brown or brownish in color, coiled in 0.5-4 turns.
Seeds are kidney-shaped and curved, pale, yellow or yellow-brown. The weight of 1000 seeds is 1.5-2.7 g.
The color of flowers and the shape of the fruit are characteristic species and varietal traits of alfalfa.
Yellow alfalfa
The bush is spreading, stems semi-prostrate or erect, covered with hairs. The root system is strong, penetrates to a depth of more than 4 m. Lateral roots are long, horizontally branching.
Unlike alfalfa, yellow alfalfa plants are low-growing. The root crown is larger and lies deeper than in field alfalfa. Leaves are trifoliate, weakly pubescent. Flowers are yellow, gathered in a dense shortened raceme. Pods are sickle-shaped, brown or black. The weight of 100 seeds is 0.9-1.2 g.
Ecological requirements
Temperature requirements
Seed germination begins at a temperature of 1-3°C; the optimal germination temperature is 18-20°C. Seedlings withstand frosts down to -6°C. In winter, with good snow cover, plants tolerate frosts down to -30…-40°C.
The most resistant to negative temperatures varieties come from mountain regions and from areas with severe winters. Winter-hardy alfalfa varieties are distinguished by a prostrate leaf rosette; in less winter-hardy ones it is erect; in medium-winter-hardy ones it is semi-raised. In frost resistance, alfalfa surpasses red clover.
Winter hardiness strongly depends on the time of the last cutting. The last cut should be carried out 30-45 days before the onset of stable frosts, so that plants have time to regrow, form a rosette and accumulate a sufficient reserve of nutrients.
In the Non-Chernozem zone, soil liming significantly increases the winter hardiness of alfalfa. In spring, regrowth begins at a temperature of 7-9°C. In the first half of summer, at an average daily temperature of 22-23°C, the period from regrowth of the aboveground part to the onset of flowering is 42 days; in the second half of summer, that is, by the third and fourth cuts, about 55 days. The sum of positive temperatures required from regrowth to the beginning of flowering in alfalfa is 800°C.
Moisture requirements
Alfalfa is a drought-resistant plant, but responsive to moisture. Drought resistance is determined by a very powerful, deeply penetrating root system, which consumes moisture not only from the soil but also from the subsoil layers. Alfalfa is a typical mesophyte, that is, for good growth of the aboveground part, sufficient moisture supply is necessary; in water consumption it is second only to rice.
During germination, seeds absorb water up to 100% of their own mass. Alfalfa is demanding on soil moisture and resistant to atmospheric drought. The optimal moisture content of a meter layer of soil required to obtain a high hay yield is 80% of minimum moisture capacity, therefore, for a forage crop, abundant irrigation is recommended after each cut. For a seed crop, they strive to maintain moderate soil moisture.
The transpiration coefficient is 700-900.
Yellow alfalfa is somewhat more drought-resistant than field alfalfa. Blue-hybrid alfalfa can withstand flooding by flood waters for up to 10-12 days; yellow and yellow-hybrid, up to 25-30 days.
Light requirements
Alfalfa is a long-day plant. The yield of green mass and seeds of various alfalfa varieties is higher at a 20-hour day length than under natural or shortened (10 h) (VIR).
Alfalfa is more light-demanding than red clover, therefore, when undersown under the cover of well-developed cereal crops, it is thinned more strongly.
Soil requirements
Alfalfa prefers fertile, loose and cultivated limed sod-podzolic, well-aerated chernozem, chestnut, gray forest soils. It can grow on sandy, clayey and solonetzic soils.
It poorly tolerates close groundwater occurrence, stony and gravelly soils. It does not tolerate strongly acidic soils. At pH 5, nodule development almost does not occur, and in single nodules bacteria do not fix nitrogen from the air. The optimal acidity is pH 6.5-7.
Alfalfa is characterized by salt tolerance, which is:
- for chloride ion: before sowing — 0.20%, in the budding phase — 0.60%, after the first cut — 0.60%;
- for sulfate ion: during budding — 0.90%, after the first cut — 0.90%.
Chloride ions have a more negative effect than sulfate ions at equal concentrations; the negative effect of carbonate ions exceeds that of chloride ions.
When sowing alfalfa on strongly saline soils with pH more than 8-8.2, preliminary leaching with a large amount of water is carried out.
Plant nutrition
Alfalfa is distinguished by a large removal of nutrients from the soil, which is associated with a large yield of aboveground mass, characterized by a high protein content.
For the formation of 1 t of hay, 6 kg P2O5, 17-20 K2O are consumed, as well as a lot of calcium and magnesium.
In some cases, alfalfa responds well to the application of sulfur fertilizers.
Vegetation
Alfalfa is a spring plant. In the year of sowing it gives a seed yield or 2-3 hay cuts.
Only one stem grows from the seed. New shoots (stems) develop from buds located on the root crown. Stems live no more than one year; with multi-cut use, several weeks. When old shoots die, part of the branching roots usually also dies. New shoots cause the formation of new thin lateral roots.
In the first year, plants mainly develop the underground part, reaching 40-60 cm in depth during the first month of vegetation; in the second and subsequent years of life, the aboveground part.
Vegetative renewal depends on the stability and vital activity of the root crown and the buds located on it, therefore, when grazing it by animals or mowing, it is necessary to monitor the preservation of the root crown.
Alfalfa creates a very large leaf surface: per 1 ha, with average plant development, the leaf surface is 50 ha.
The duration of vegetation from emergence to seed ripening in the first year of life is 130-140 days; in the second and subsequent years, 110-120 days.
Growth phases in the first year of life and the timing of their onset after sowing:
- emergence — 10-12 days;
- branching — 35-40 days;
- budding — 61-65 days;
- flowering — 75-80 days;
- ripening — 130-140 days.
In summer sowing, seedlings appear on the 7th-8th day, and branching occurs on the 22nd-25th day.
Growth phases of alfalfa in the second and subsequent years of life:
- regrowth;
- stem elongation, or branching — 26-28 days;
- budding — 40-42nd day;
- flowering — 50-52nd day;
- pod formation;
- browning of pods, or ripening — 115-120th day.
Flowering is extended by approximately 2-3 weeks, which leads to uneven seed ripening.
Plants regrow well at an average daily temperature of 7°C. Therefore, the growing season lasts from early spring to late autumn. The period from regrowth to the beginning of flowering usually does not exceed 40 days. Under favorable cultivation conditions, alfalfa can grow in one place for a long time. Thus, in Turkmenistan it can grow in one field for up to 20-30 years. Usually the duration of use in field crop rotations is 2-3 years, in forage rotations 3-4 years, in ley fields 5-6 years.
Crop rotation
In field crop rotations of the steppe zone, alfalfa is usually undersown under the cover of spring cereals of group I, less often under millet, Sudan grass or in the rows of maize. In cotton-growing areas it is sown without a cover crop. The choice of place in the crop rotation is determined by specific conditions and planned use.
Winter cereals are poorly suitable, since when sown under their cover, alfalfa is strongly suppressed.
For alfalfa, to obtain high yields of hay and seeds, it is necessary to allocate fields clean of weeds, fertile and well supplied with moisture.
Under rainfed farming conditions of the steppe zone, good predecessors for alfalfa can be cereals following black fallow, maize, oil flax, melons and gourds. Sugar beet is a poor predecessor, as it strongly dries out deep soil horizons. Under irrigation, alfalfa can be placed after any predecessor.
In the Non-Chernozem zone, in special forage crop rotations, it is grown in ley fields with a period of use of 3-4 years.
Fertilization
Alfalfa is characterized by a large removal of phosphorus, potassium, calcium and magnesium from the soil.
It is responsive to the application of organic fertilizers under the cover crop. For example, application of 20 t/ha of manure under cover barley increases the yield of alfalfa hay by 75% (former Don Experimental Station); with application of 45 t/ha of manure under cover winter rye, the hay yield of an alfalfa-crested wheatgrass mixture increased by 1.3 t/ha (Kazan Agricultural Institute).
Manure is applied in fallow for winter crops or for industrial crops, counting on alfalfa using the residual effect of manure. In the steppe zone, the recommended rate of manure application is 15-20 t/ha; in areas of sufficient moisture, 25-40 t/ha.
Strongly saline soils are gypsumed and organic fertilizers are applied. For example, application of gypsum in an amount of 4-5 t/ha and manure 20-30 t/ha ensured an increase in crop yields in the crop rotation by 20-60%, including alfalfa hay by 1.1 t/ha.
Alfalfa is sensitive to phosphorus nutrition in the early period of development, especially in the first month of life, which also positively affects development in subsequent years. Recommended rates of mineral fertilizers are P45-60K45-60 (according to other recommendations N30-45P60-90K60-90); for alfalfa-cereal grass mixtures — N90P60K30. On chernozems, it is recommended to apply 200-300 kg/ha of superphosphate; under irrigation, at least 300 kg/ha of superphosphate, 100 kg/ha of potassium fertilizers. Phosphorus doses can be reduced if its content in the soil is more than 17 mg/100 g.
Nitrogen fertilizers are recommended for use on poor soils. They are applied in early spring in cold weather, when nodule bacteria are not yet developed, in an amount up to 30 kg/ha.
At sowing, row application of granular superphosphate together with seeds is recommended at a rate of 50 kg/ha, or P10-30.
Pre-sowing treatment of seeds with molybdenum micronutrients is highly effective, at the rate of 100 g of ammonium molybdate per 1 hectare seed norm, diluted in 400 ml of water. This treatment is especially important when sowing in soils with low molybdenum content, such as sod-podzolic and gray forest. Pre-sowing treatment of seeds with molybdenum and boron micronutrients increases seed germination and increases green mass yield by 17% (Shchedrina D. I., Voronezh Agricultural University).
Soil tillage
After cereal crops, soil tillage for alfalfa includes stubble disking, then, after 2-4 weeks, plowing with a plow with a skimmer to a depth of 25-30 cm. If perennial root-suckering weeds are present, disking is performed twice; if annual weeds are present, disking in 1-2 passes to 5-8 cm; after weed regrowth, plowing with leveling of furrow bottoms and ridges. In case of early plowing, treatment of the half-fallow type is possible.
Increasing the plowing depth from 18 to 25 cm contributes to an increase in hay yield by 0.3 t/ha (Krasnokutsk Experimental Breeding Station of the Research Institute of Agriculture of the South-East, Saratov region), and from 20 to 30 cm in the first year of use by 0.7 t/ha, or from 34.7 c/ha to 42.2 c/ha; in the second year by 0.2 t/ha, or from 27.6 c/ha to 30.4 c/ha (Bezenchuk Experimental Station, Samara region).
Pre-sowing soil tillage when sowing in early spring under the cover of cereal crops consists of harrowing in 2-3 passes. If Sudan grass, millet or other late-sown crops serve as cover crops, then before sowing 2-3 cultivations are performed at 3-5 cm with simultaneous harrowing.
Pre-sowing treatment for summer coverless sowing includes layer-by-layer cultivation with harrowing: the first to a depth of 12-14 cm, the second 8-10 cm, the third 3-4 cm. In arid conditions, after each cultivation the field is rolled. In summer sowing, surface tillage can be carried out immediately after harvesting winter crops for green fodder, including disking, cultivation and rolling.
In steppe regions, pre-sowing rolling of the soil is of great importance. According to data from the former Krasnokutsk State Breeding Station, rolling the soil before and after sowing increased seed germination by 30%, or from 78 plants per 1 m2 to 102 plants per 1 m2.
In Central Asia, under irrigation, in addition to autumn deep plowing, spring re-plowing of clayey structureless soils that settle over winter, or deep chiseling with simultaneous harrowing, is sometimes required. An important method of soil preparation on irrigated lands is field leveling, ensuring uniform distribution of irrigation water over the area.
On fields infested with perennial weeds, before plowing, their rhizomes are combed out and removed from the plot.
Sowing
Pre-sowing seed treatment includes cleaning from foreign impurities using grain-cleaning machines. If dodder seeds are present, special cleaning with special machines is used. Pre-sowing treatment may also include treatment with bacterial preparations and micronutrients.
For seed treatment against diseases (ascochyta, fusarium, gray mold, anthracnose, bacteriosis, seed molding), preparations TMTD, Aktamyr can be used.
In the southeast in arid regions, the seeding rate of alfalfa is 8-12 kg/ha; in moist regions, 12-16 kg/ha; under irrigation, 14-16 kg/ha; in the Non-Chernozem zone, 14-18 kg/ha.
Sowing is carried out with grain-grass seeders, for example, SUT-47, SZTN-47, SZT-3.6, to a depth of 2-3 cm by the conventional row method. When sowing under the cover of spring cereals, sowing is carried out early — simultaneously with sowing the cereal crop. When sowing under the cover of maize or sorghum, first the cover crop is sown, then alfalfa. The seeding rate of maize is 25-30 kg/ha, sorghum — 15-20 kg/ha.
If sowing is carried out with conventional row seeders, it is done across the rows of the cover crop. The seeding rate in this case is 17-20 kg/ha, or 9-9.5 million germinating seeds per 1 ha.
In areas of insufficient moisture, a semi-cover sowing method can be used, that is, with an incomplete seeding rate of the cover crop.
Crop care
On undersown alfalfa crops, the cover crop is harvested at optimal times. Forage cover crops should be mowed for green fodder, not for hay. Cereals are harvested by direct combining at a cutting height of at least 12-14 cm (according to other data, at least 20 cm) with simultaneous removal of chopped straw. A low cut worsens the conditions for overwintering of plants and leads to thinning of sowings.
With sufficient moisture supply in the soil, it is recommended in early autumn to top-dress alfalfa with phosphorus and potassium fertilizers at the rate of 100-200 kg/ha of superphosphate and 50-100 kg/ha of potassium salt, or P45-60K45-60, to increase the frost resistance of plants.
In winter, in steppe and forest-steppe regions, snow retention is carried out.
The intensity of spring regrowth and frost resistance depend on the time and height of autumn mowing of alfalfa, which should be carried out at a height of 7-8 cm no later than 30-40 days before the onset of stable frosts.
In coverless cultivation of alfalfa, crop care includes rolling the soil after sowing, breaking the soil crust with light ring rollers or rotary hoes, combating weeds, pests and diseases. Weed control in forage alfalfa crops or grass mixtures usually comes down to mowing when plants are 15-20 cm high. The cutting height is set so that the growing point of cultivated plants is not damaged. Also, on pure alfalfa sowings against annual cereal weeds, pre-sowing soil herbicides can be applied under cultivation; against dicotyledonous weeds, spraying with approved herbicides is carried out in the phase of 2-3 true leaves.
In early spring, alfalfa or alfalfa grass mixture sowings are harrowed across the rows. Loosening the soil with disk implements can contribute to rejuvenation of old herbage. In the steppe zone, autumn slotting of sowings gives good results, ensuring moisture accumulation during the autumn-winter period.
Diseases
Brown spot
Brown leaf spot affects leaves, stems and pods of alfalfa. The disease appears in late spring on the lower leaves, then quickly covers the whole plant. Affected leaves fall off. For control, seed treatment with 80% TMTD is carried out; in autumn or spring, harrowing across the rows; early first cut before fungal sporulation; treatment of sowings during vegetation with 1% Bordeaux mixture.
Ascochyta blight
Ascochyta blight affects leaves, stems, peduncles, pods and seeds of alfalfa, sometimes the upper part of the root, which leads to its cracking. For control, dusting of sowings with sulfur is carried out; plant residues of diseased plants are destroyed (burned); plowing of old alfalfa fields and early mowing for hay. Also, the use of phosphorus-potassium fertilizers reduces stand infestation by 3.5-4 times.
Rust
Alfalfa rust affects leaves, stems and pedicels of alfalfa. It leads to rapid leaf drop; affected stems break easily. With moderate spread of the disease, yield decreases by 30%. For control, early harvesting for hay and destruction of weeds are carried out; when grown for seed, dusting with sulfur.
Wilt
Bacterial wilt, or wilt, affects the vessels of the root and stem, as a result of which plants acquire a depressed appearance, become dwarfed, leaves turn yellow, and in hot weather turn brown. The disease is very harmful. For control, proper crop rotation, destruction of plant residues, and maintenance of a high agronomic background are important.
Pests
Alfalfa bug
The alfalfa bug damages leaves, buds and flowers of alfalfa, which quickly fall off. When affected in the early period, the upper part of the shoot dies. For control, new alfalfa sowings are placed at a considerable distance from old alfalfa fields; sowing is carried out under the cover of cereal crops; stubble is mowed at a low cut; treatments are carried out with preparations Bitoxibacillin, Fastak, Altalf, Tsunami, Alpha Cipi, Alphas, Rotalaz, Faskord, Tsezar, Piket, Decis, Diazinon, Bi-58 New, Danadim, Rogor S, Di-68, Nugor.
Phytonomus
Phytonomus, or alfalfa leaf weevil. Beetles begin to feed on alfalfa leaves in early spring; larvae cause great damage to apical buds, buds and flowers. For control, disking in 2-3 passes in early spring is carried out; mowing alfalfa for hay; using alfalfa for seed two years in a row is not allowed. In the fight against Phytonomus larvae, biological preparations can be used, for example, entobacterin, boverin, dendrobacillin at 2-3 kg/ha.
Tychius weevil
Tychius weevils are distributed in all regions of alfalfa cultivation. After overwintering, beetles feed on leaves in spring, then on buds, buds and flowers. The damage caused by Tychius increases sharply with a lack of precipitation in early spring. For control, alternation of using alfalfa for hay and for seed is practiced.
Alfalfa seed eater
Females of the seed eater lay eggs inside green seeds during fruit set. Larvae hatching from eggs eat out the contents of the seed. During the summer, the alfalfa seed eater can produce 1-3 generations, so seed damage can occur in the first and second cuts. For control, seed cleaning, disking of alfalfa sowings and approved chemical preparations are used.
Nodule weevil
Nodule weevils damage alfalfa plants from emergence and during regrowth. Larvae of the weevil harm roots and nodules. For control, treatment with approved chemical preparations is carried out in early spring, before beetles lay eggs.
Meadow moth
To control the meadow moth, spraying of sowings is carried out with preparations Lepidocide, Bitoxibacillin, Diazinon, Karbofos, Karbofot, Fufanon, Kemifos, Bunchuk, Zolon, Fort, Sharpei.
Harvesting
Pure alfalfa sowings, as a rule, are harvested for haylage, feed obtained by high-temperature drying, and hay leaf.
Maximum forage mass yield is achieved when harvested in the flowering phase, while maximum quality is in the budding phase. Therefore, harvesting begins in the period from the end of the budding phase (early mowing) to the beginning of the flowering phase (moderate mowing). Later harvesting times lead to deterioration of the chemical composition of plants and a decrease in hay quality.
Hay harvesting is carried out with hay-harvesting machines or machines that condition stems, for example, KPF-1.8 and KPV-3.0. For raking hay and forming windrows, side rakes GBU-6.0 or wheel-finger rakes GVK-6.0 are used. Baling hay from windrows is carried out using pick-up balers PSB-1.6 and PPV-1.6. Bales of pressed hay are transported to the place of permanent storage.
In the steppe and forest-steppe zones with natural moisture, alfalfa is cut 2-3 times; under irrigation, 4-5 times. Hay can be harvested with mower-conditioners, for example, E-301, E-302, E-303; conditioning hay shortens drying time by 30%. Tedding the mown mass also accelerates drying.
The method of active ventilation and pressing reduces hay losses from leaf shattering, improving its quality by increasing protein and carotene content. The method provides for additional drying of the mass wilted after conditioning and tedding with a moisture content of 35-45% in stacks or hay sheds to a moisture content of 15-17%.
When using alfalfa for haylage, it is mowed with conditioning in the flowering phase. Harvesting begins at a moisture content of at least 60%.
For the purposes of harvesting vitamin-grass meal and pellets, mowing is carried out at the beginning of budding. The green mass is dried and processed. To reduce carotene losses, grass meal and pellets are stored in polyethylene bags in dark rooms at a moisture content of 10-12%.
Voronezh Agricultural University proposed a technology providing for the harvesting of hay leaf, which in nutritional value is not inferior to more expensive grass meal and pellets (Shchedrina D. I. et al., 2002).
Features of cultivation under irrigation
Alfalfa and alfalfa grass mixtures in the steppe zone are often grown under irrigation in forage crop rotations or in ley fields.
The seeding rate of alfalfa seeds in pure form, as a rule, is 15 kg/ha; in two- and three-component grass mixtures, 6-8 kg/ha; in a four-component mixture, 4-5 kg/ha.
When choosing grasses and determining the composition of grass mixtures for floodplain lands, the duration of their flooding is taken into account. Blue-hybrid alfalfa can withstand flooding for 10-12 days; variegated-hybrid and yellow-hybrid, 20 days; yellow, 25-30 days.
Nutrient removal with a planned yield of 50 t/ha of green mass by an alfalfa-cereal grass mixture is 380 kg/ha nitrogen, 800 kg/ha phosphorus and 390 kg/ha potassium. Therefore, in top dressing it is recommended to apply annually N30-45 for each cut (total N180), P60-90K60-90. Nitrogen fertilizers are recommended to be applied with irrigation water; phosphorus-potassium fertilizers in autumn under main tillage; on floodplain lands, after flood recession.
The irrigation regime is determined by the moisture reserve in the soil and the amount of precipitation during the growing season. The optimal soil moisture in the 70-cm layer should be 70-80% of minimum moisture capacity.
Under irrigation, on plots prepared for sowing alfalfa, reserve irrigations are often carried out with a rate of 2000 m3/ha of water; on saline soils, leaching irrigations. Reserve irrigations contribute to an increase in alfalfa hay yield by 1-1.5 t/ha.
In the year of sowing alfalfa, irrigations of 600-800 m3/ha can also be carried out. The first irrigation of the first year of alfalfa life is given during the appearance of the 6th-7th true leaf. The next year, harrowing is carried out to remove stubble and slightly loosen the topsoil. Under irrigation, irrigations are usually carried out from regrowth to the first cut, which, for example, in the Hungry Steppe increases hay yield by 40%.
The first irrigation in conditions of arid spring is done in early May, then after each cut. In very dry years, irrigations are also carried out between cuts. In years with average moisture, usually 3-4 irrigations of 500 m3/ha are carried out. On soils light in particle-size composition, the irrigation rate is reduced to 300 m3/ha, but the number of irrigations increases. After mowing, irrigation is done no later than 3-5 days.
In cover cultivation of alfalfa, the first irrigation is done immediately after harvesting the cover crop with an irrigation rate of 500-600 m3/ha. In coverless spring sowing, the first irrigation is done 40-50 days after emergence with an irrigation rate of 300-400 m3/ha, then 500 m3/ha after each cut.
Alfalfa of the second year of life is irrigated 10-14 days from the beginning of spring regrowth. 5 days before mowing for hay, irrigation is also recommended to avoid soil drying during harvesting and to ensure rapid regrowth of cut plants. After mowing and hay harvesting, the field is harrowed with heavy harrows in two passes.
In irrigated regions, the number of irrigations depends on groundwater depth, soil texture, plot relief, irrigation method and moisture reserves in the soil. In all cases, soil moisture when cultivating alfalfa for hay in a meter soil layer should be at least 70-75% MMC. Thus, at soil moisture of 55% of minimum moisture capacity, hay yield was 7.3 t/ha, and at 75%, 8.9 t/ha (Bezenchuk Experimental Station, Samara region).
Irrigations are carried out during alfalfa regrowth every 15-25 days and during intensive growth every 8-15 days.
Irrigation and fertilizer application are effective at a stand density of at least 300-400 plants per 1 m2. According to data from the Research Institute of Agriculture of the Central Chernozem Zone named after V. V. Dokuchaev (Voronezh region), the hay yield of a grass mixture of variegated-hybrid alfalfa, awnless brome and meadow fescue under irrigation was 13.9 t/ha.
Growing alfalfa for seeds
For seeds, alfalfa is grown in seed-growing farms in specialized crop rotations; in farms not specialized in grass seed production — on out-of-rotation plots, diversion fields, in soil-protective or fodder crop rotations. Alfalfa crops for seeds are recommended to be placed on southern slopes.
To prevent overgrowth and lodging of seed alfalfa crops, especially in wet years, it is not recommended to place them on very fertile or well-fertilized fields. It is better to allocate medium-fertility soils with a humus content of up to 3% for seed stands, but provided with phosphorus, potassium, calcium, boron, and molybdenum.
Soil cultivation for seed alfalfa crops is similar to cultivation for fodder crops. The main task is to ensure protection from weeds, for example, with the help of improved autumn plowing or semi-fallow.
Phosphorus-potassium fertilizers are applied based on the planned yield; in general cases, the recommended rate is P60K60. Alfalfa responds well not only to molybdenum fertilizers but also to boron fertilizers, which improve fertilization and seed set. For example, under forest-steppe conditions, the combined application of boron and molybdenum to the soil gave a seed yield increase of 90 kg/ha (Shchedrina D. I.).
In spring, early spring harrowing and leveling of autumn plowing are carried out; soil herbicides are applied for pre-sowing cultivation, for which beet cultivators USMK-5.4 are better suited to a depth of 3–4 cm. Before and after sowing, rolling is carried out: before sowing — with smooth rollers, after — with ring-ribbed rollers.
The sowing method is coverless wide-row with row spacing of 60–70 cm or wide-row band sowing according to schemes 60×15 cm or 70×15 cm.
In the arid steppe, sowing is carried out in early spring simultaneously with the sowing of early cereal crops, which makes it possible to obtain seeds in the sowing year. Under conditions of unstable and sufficient moisture, alfalfa is sown in spring or summer.
The seeding rate is 1.5–2 kg/ha or 2–3 kg/ha at 100% sowing suitability (0.25–0.5 million seeds/ha), or 10–25 plants per 1 m2. For summer coverless sowing, the rate is increased by 15–20%. The sowing depth of seeds on loamy chernozems is 0.5–1.5 cm; on other soils — 2–3 cm. Sparse placement of plants promotes the formation of a productive stand as a result of improved photosynthesis and root nutrition, and better illumination. In wide-row sparse crops with a row spacing of 45 cm and a seeding rate of 0.25–0.5 million germinating seeds/ha, 160–200 generative stems per 1 m2 are formed with 10–15 inflorescences in each, which is more favorable for pollinator activity.
Crop care includes destruction of the soil crust before emergence, and control of weeds, diseases, and pests. Crops are top-dressed with phosphorus-potassium fertilizers in autumn and early spring.
On coverless early spring wide-row crops in the first year of alfalfa life, harrowing after emergence is carried out to control weeds; in the second and subsequent years — disking in early spring before regrowth. Also, inter-row treatments and hilling are carried out annually. To prevent overgrowth and lodging, attention should be paid to the selection of resistant varieties, hilling, and autumn root pruning. Horizontal pruning in autumn or spring before regrowth is done to a depth of up to 25 cm. Starting from the 2nd year of alfalfa life, pruning is especially effective in years of sufficient moisture; it also promotes mineral plant nutrition. Pruning with flat-cutters increases the rate of regrowth of young roots, increases their absorbing capacity, and increases the period of use of seed stands and their productivity. Pruning is advisable to carry out in autumn, since the resulting slots promote moisture accumulation in the autumn-winter-spring period. However, pruning is not carried out in dry years, as this reduces seed yield.
Spring disking of crops before regrowth reduces the number of alfalfa pests. With a high number of pests or detection of disease signs, crops are treated with approved preparations.
For better pollination of seed alfalfa crops, it is recommended to use leafcutter bees or honey bees. Thus, with the work of 2–7 honey bees or 1–5 leafcutter bees per 1 m2 of seed alfalfa stand, while observing cultivation technology, the seed yield over 2 years was 320–1000 kg/ha (Gagarinsky specialized farm, Kalashnikov collective farm, Levokumsky district, Stavropol Krai). If insects open more than 90% of the formed flowers, it is considered that the crops are provided with pollinators very well; 71–90% — well; 50–70% — satisfactorily; less than 50% — poorly. With very good and good pollination, the field of seed alfalfa looks gray, and the smell of flowering plants is not felt. Conversely, little opening of flowers by the end of the day and a specific aroma indicate a lack of pollinators.
When preparing seed stands for harvesting, species weeding and mowing of the edges of plots are carried out.
Higher seed yields are usually obtained from the first cut. Direct combining begins when 90–95% of the beans of the stand turn brown. To reduce losses, combines and transport vehicles are sealed. Seed harvesting by direct combining can be carried out with preliminary desiccation of the stand with magnesium chlorate at a rate of 18–20 kg/ha or reglone at 4–5 kg/ha. Desiccation is performed when 80–85% of the beans turn brown, and harvesting — 6–7 days after treatment.
Under the conditions of the steppe and forest-steppe zones, seeds can be obtained from the first, one-and-a-half, or second cut. If the weather in May was hot and dry, it is more advisable to collect seeds from the first cut. If cool and wet weather has set in, and pests are widespread in the crops, it is recommended to mow the seed alfalfa at the budding phase or 7–10 days before its onset. Thus, with mowing at the budding phase, seeds are obtained from the second cut; in the second case — from the one-and-a-half cut.
The cause of low seed yields in the forest-steppe zone is usually excess precipitation during the flowering phase, which causes overgrowth and lodging of crops, as well as deterioration of pollinator activity. Optimal conditions for obtaining a high seed yield of alfalfa of the 2nd year of life develop when no more than 250 mm of precipitation falls during the vegetation period, and most of it should fall in the period from regrowth to flowering (Shchedrina D. I., Voronezh Agricultural University). The number of days without precipitation during flowering should be 60%, the hydrothermal coefficient 0.6–1.0, the optimal average daily air temperature in this phase 21–22 °C, in the fruit formation phase 19–20 °C, relative air humidity — not more than 70%.
The second cause of low seed yields is a lack of insect pollinators. Therefore, seed crops are recommended to be placed on southern slopes of diversion fields near forest belts, gullies, and ravines in elongated plots of 20–25 ha, since wild pollinating bees usually fly from their nesting sites no more than 200–250 m. The number of insect pollinators also depends on weather conditions and varies from 286 to 2320 per ha. To preserve insect habitats, natural fodder lands are not plowed and pesticides are not used in nesting sites. For the reproduction of wild insect pollinators, it is recommended to create special micro-sanctuaries that are not used for arable land or livestock grazing. To create conditions for insect settlement in alfalfa crops, first-year crops are sown around the perimeter with strips of honey plants, for example, sainfoin or phacelia, in strips of 6–8 meters. In addition, strips of cereal grasses are placed inside seed plots, where nests of wild insect pollinators appear. Other flowering fields should be at some distance so that during alfalfa flowering they do not distract pollinators to other plots. For additional pollination, artificially bred leafcutter bees can be used at 20–30 thousand per 1 ha; they are capable of increasing alfalfa seed yield by 2–3 times.
One of the causes of low seed collection under production conditions is losses during harvesting, because by the time of harvesting alfalfa has a powerful vegetative mass with high moisture, while seeds account for only 2–10% of the mass, and they are also very small and fluid. This causes difficulties in separating seeds from the heap. Therefore, a technology was proposed that provides for only collecting the above-ground mass in the field, while threshing, cleaning, and drying of seeds are carried out at the edge of the plot or at a special stationary point. According to tests conducted by Voronezh Agricultural University, pneumatic-inertial separators best cope with separating seeds from the unwinnowed heap. The sorting line also provides for additional threshing of unthreshed plant parts. The proposed technology was tested at the Berezovskoye training farm of Voronezh Agricultural University.
Seed production under irrigation
Seed plots are allocated on stands of the second or third year of alfalfa plant life at a stand density of 50–70 plants per 1 m2. On soils with deep groundwater occurrence or low precipitation during the winter period, moisture-charging irrigations of 1500–2000 m3/ha are carried out. Seeds on such soils are obtained from the first cut.
In autumn or early spring, seed stands are top-dressed with 400–500 kg/ha of superphosphate and 100–150 kg/ha of potassium salt with simultaneous harrowing with heavy tooth harrows.
Weeds are removed from the plots, primarily dodder, pink thistle, and Johnson grass. Against phytonomus, one or two treatments with phosalone (2.5 kg/ha) or actellic (1.5 kg/ha) are carried out.
On meadow-bog soils with groundwater close to the soil surface, high seed yields are obtained from the second cut.
Vegetation irrigations of seed crops are carried out during regrowth and at the budding phase when obtaining seeds from the first cut, or at the beginning of flowering when obtaining seeds from the second cut. The irrigation rate is 950–1000 m3/ha.
Seed harvesting begins when 70–80% of the beans located on normally developed stems turn brown. Harvesting is carried out by a two-phase method. First, alfalfa is mowed with header harvesters or mowers with mounted windrowers. After the mass dries, that is, approximately 5–6 days after mowing, the dried mass is harvested.
To improve the harvesting of alfalfa seed stands, as well as clover and cereal grasses (timothy, fescue, cocksfoot), the SK-5 "Niva" combine uses attachment 54-108A — a rubbing device, which together with the threshing drum ensures the rubbing out of legume grass seeds from the hulls.
The combine discharges a heap that includes seeds and half-broken beans. The heap is passed through special clover hullers to separate seeds from the beans. Then the seeds are separated from impurities using grain-cleaning machines and electromagnetic sorting EMS-1. The moisture content of seeds before storage for long-term storage should be not more than 13%.
Technology proposed by the Volgograd Agricultural Institute
The Volgograd Agricultural Institute proposed a technology for obtaining 800–900 kg/ha of alfalfa seeds. With observance of agrotechnics, seeds can be obtained from one plot for 3–4 years. Therefore, the seed plot is recommended to be located outside crop rotation.
For autumn plowing, P180-200K150-200 is applied as a reserve for 3–4 years. Soil cultivation is usual. The sowing method is row or wide-row two-line 70×15 cm. The seeding rate is 2–3 million/ha of germinating seeds, or 4–6 kg/ha of seeds at 100% sowing suitability.
Irrigation regime: the first irrigation is done at the branching phase, the second — at the budding phase, the third — during seed filling. Before flowering, the moisture content of the meter soil layer should be maintained at 75% of the lowest moisture capacity; after flowering — 65%.
At the budding phase, top dressing is done at a rate of 60 kg of nitrogen per 1 ha.
Harvesting is carried out in two phases, beginning when 70–75% of the beans turn brown. Alfalfa is mowed into windrows; after 5–6 days it is threshed with a combine. Seeds are cleaned of foreign impurities and stored.
Varieties
Blue alfalfa
Chitinka (1999). The variety was developed by the Transbaikal RIA.
Diana (2000). Developed by the Ershov Experimental Station of Irrigated Agriculture.
Tambovchanka (2000). Developed by the Morshansk Breeding Station.
Talisman (2002). Developed by the ARRI of Irrigated Agriculture.
Soleustoychivaya (2004). Developed by the ARRI of Fodder and the ARRI of Irrigated Agriculture.
Uzen (2006). Developed by the Ershov Experimental Station of Irrigated Agriculture.
Variable alfalfa
Zaykevicha. The variety was developed by the Poltava Agricultural Experimental Station. Of hybrid origin. The bush is spreading. Stems are not coarse; the average height when harvested for hay is 57 cm, for seeds — 76 cm. Mid-season. Winter hardiness is high. It freezes out only in very cold snowless winters. Damage by brown spot and rust is average and below average.
Marusinskaya 425. Developed at the Morshansk Experimental Breeding Station in 1938 by mass selection from a local hybrid population. Belongs to the yellow-hybrid variety type. The bush is semi-prostrate, spreading. Stems are thin; when cut for hay, the average stand height is 45 cm, for seeds — 65–67 cm. Winter-hardy, late-ripening. Tolerates short-term flooding. Damage by brown spot and rust is weak.
Semirechenskaya local. A local variety of Alma-Ata Oblast. The bush is spreading. Regrowth after cuts is slow. Stems are not coarse; the average stand height before harvesting for hay is 63–70 cm, for seeds — 85–90 cm. Winter hardiness is very good. Drought resistance is low. Strongly affected by diseases. Leafiness and heat resistance are high. Zoned in Central Asia and Kazakhstan.
Tashkentskaya 3192. The variety was developed by the RI of Cotton Breeding and Seed Production by mass selection. The bush is erect. Stems are thick; branching is weak. When cut for hay, the average height is 62 cm, for seeds — 86 cm. For Central Asia, the variety is early-ripening. In cotton-growing regions it overwinters well. Damage by brown rust is average. Under irrigation it is capable of giving 5–8 cuts. Zoned in cotton-growing regions.
Vega 87 (1988).
Sarga (1992).
Pastbishchnaya (1996).
Voronezhskaya 6 (1997). Developed by the Voronezh Experimental Station for Perennial Crops.
Rostovskaya 60 (1997). Developed by the ARRI of Grain Crops (Rostov Oblast).
Kameliya (1999). Developed by the Penza RIA.
Bibinur (2000). Developed by the Bashkir RIA.
Uralochka (2003). Developed by the Ural RIA.
Nakhodka (2004). Developed by the Moscow Breeding Station.
Yellow alfalfa
Krasnokutskaya 4009. The variety was developed by the Krasnokutsk Experimental Breeding Station in 1939 by mass selection from a hybrid population. The bush is erect, spreading. Stems are of medium thickness; stand height before cutting for hay is 60–62 cm, for seeds — 83 cm. Late-ripening. Winter hardiness is high. Damage by brown spot is below average; by rust — weak. Regrowth after cutting is slow. Zoned in Volgograd, Orenburg, Saratov oblasts, and also Aktobe Oblast of Kazakhstan.
Kubanskaya zheltaya (1948).
Pavlovskaya 7 (1957).
Yakutskaya zheltaya (1989).
Hop clover alfalfa
Mira. The variety was developed by the ARRI of Fodder in 1999.
References
1. Vavilov P. P., Gritsenko V. V., Kuznetsov V. S. et al. (1986). Crop Production. Ed. Vavilov P. P. 5th ed., revised and enlarged. Moscow: Agropromizdat.
2. Kolomeichenko V. V. (2007). Crop Production/Textbook. Moscow: Agrobusinesscenter.
3. Niklyaev V. S. (2000). Fundamentals of Agricultural Production Technology. Agriculture and Crop Production. Moscow: Bylina.
