Soybean

Economic importance

As the main source of vegetable protein and edible oil, soybean is undoubtedly the most important food legume in the world. Although soybean is produced mainly for dry seed, the widespread use of immature seeds, especially in East Asia, makes soybean an important vegetable crop.

Chemical composition of seeds: protein — 30–52% (second only to lupine), fats — 17–27%, carbohydrates — 6–20%, minerals (potassium, phosphorus, calcium), fat-soluble vitamins (C, B, E).

Soybean is recommended for the dietary nutrition of diabetic patients. Its protein is highly digestible (3.5–4 times more than that of cereal crops) and water-soluble. Among grain legumes, it has the richest composition of essential amino acids. The main seed protein of soybean is glycinin, which has the ability to coagulate (curdle) upon acidification. Soybean protein includes the amino acids lysine 2.7% (wheat protein has 0.25%), methionine, and tryptophan, which determine its feed value.

Soybean is cultivated for food, feed, and industrial purposes.

As food it is used in the form of oil, margarine, soy cheese, milk, flour, confectionery, canned goods, and other products. Soybean seeds serve as raw material for the oil-pressing industry. Soybean oil is a semi-drying oil (iodine value 107–137) and is used for food after refining. It is also used in soap making, the paint and varnish industry, and the production of glycerol, linoleum, lubricating oils, gelatin, and lecithin. Soybean oil accounts for 38% of world production, whereas sunflower oil accounts for 17%.

For feed purposes, soybean is used in the form of cake, meal, and soybean flour. Meal contains 40% protein, 1.4% fat, and about 30% nitrogen-free extractives. Cake is also used as an additive in bread baking and in the manufacture of pasta and confectionery.

Canned goods and sauces are produced from immature soybean seeds. In Japan and China, immature seeds in the pod are boiled in salted water or prepared in the pod. The pods themselves are too fibrous to eat.

Previously, soybean was grown for green fodder and for silage in mixtures with maize. 100 kg of green mass contains 21 feed units and 3.5 kg of protein. It can be used for the production of grass meal. 100 kg of hay — 51 feed units, 15.4% protein, 5.2% fat, 38.6% carbohydrates, 7.2% minerals, 22.3% fiber.

At present, soybean is mainly grown for seed. Mixed crops of soybean with heat-loving grain crops, for example, Sudan grass, maize, and sorghum, are considered promising in feed production.

100 kg of soybean stems equal 32 feed units and contain 5.3 kg of protein. Soybean straw is readily eaten by sheep and goats.

100 kg of seeds contain 131–147 feed units and 27.5–33.8 kg of digestible protein.

Under conditions of sufficient moisture, owing to green-mass yields of up to 25–30 t/ha, leafy varieties can be used as green manure.

History of cultivation

Soybean cultivation has an ancient history; it is known that in China it was grown from 2800 BCE. According to other data, soybean was cultivated in China 6000 BCE. It has also long been grown in India, Japan, Korea, Vietnam, and Indonesia. In Asian countries, soybean is the main raw material for obtaining vegetable protein and oil, and the methods of using it in food are very diverse. More than 250 dishes are known.

At the end of the 8th century, soybean reached Europe.

Soybean was brought to the Far East from China.

Initially, soybean was a short-day and subtropical plant, but as a result of domestication, numerous forms were developed, and breeders produced varieties adapted to various latitudes. The ability to be grown widely is the main advantage of this crop.

Cultivation regions

In the world, soybean sowing areas rank first among grain legumes. In 1983, they amounted to 52 million ha in more than 40 countries; by the end of the 20th century — 67 million ha, or 42% of the total sowing area of grain legumes. Gross production is 143 million t, or 62% of the total grain harvest of grain legumes, with an average yield of 2.2 t/ha.

The United States, Brazil, and China are the largest producers. In 1994, the United States produced about 50% of world production — 136 million tonnes, Brazil — about 25 million tonnes, and China — about 16 million tonnes. In the United States, the sowing area was 27 million ha; in China — 8 million ha. Major soybean producers also include Japan, Vietnam, Korea, European countries, North Africa, North and South America (Brazil), and Australia.

In the USSR, soybean was introduced into production in 1927. The sowing area was 28.2 thousand ha. In 1983, the area was 890 thousand ha. The main cultivation regions are Primorsky and Khabarovsk Krais and Amur Oblast, where approximately 95% of all soybean sowing areas in Russia are located. Modern early-ripening varieties are also grown in areas with sufficient moisture in the North Caucasus, the Volga region, the Central Chernozem zone, the Altai, the forest-steppe of Ukraine, Transcaucasia, Central Asia, and Moldova.

In 2001–2005, in Russia the soybean sowing area was 500 thousand ha, or 29% of grain-legume sowings. Gross production was 400 thousand t, or 18% of the total grain harvest of grain legumes, with an average yield of 1.0 t/ha.

Yield

Under rainfed conditions in Russia, soybean seed yield is 1.0–1.5 t/ha; on irrigated land — 2.7–4.0 t/ha. With a high level of agricultural technology, soybean can produce even higher yields.

In Tambov District of Amur Oblast (Partizan State Farm), the average yield over several years was 1.2–1.45 t/ha on an area of approximately 7,000 ha. In Belotserkovsky District of Kiev Oblast (Terezino Experimental Farm, Ukraine), over 15 years an average of 1.8–2.0 t/ha of seeds was harvested; in Tsarichansky District of Kiev Oblast (Progress State Farm) — up to 3.06 t/ha from an area of 22 ha.

The yield of leading enterprises in the Far East and Krasnodar Krai is 2–2.5 t/ha; under irrigation — 3–4 t/ha; green mass — 15–20 t/ha.

Botanical description

Soybean (Glycine max (L.) Merr., syn. Glycine hispida Maxim.) is an annual plant of the legume family (Fabaceae).

Wild forms of Glycine max have not been found. Glycine soja (Glycine max subsp. soja) is an annual species found in eastern China that hybridizes with Glycine max and may be the wild ancestor. Another view is that Glycine max may be a cultigen obtained by hybridization of Glycine ussuriensis with Glycine tomentella (syn. Glycine tomentosa); both species occur in the wild in East Asia and southern China. Undoubtedly, the plant is of East Asian origin and domestication.

The root system is a taproot, penetrating to a depth of 1.5–2 m.

The stem is strong, erect, strongly branching, non-lodging, pubescent, forming a bush 45 to 150 cm tall.

Leaves are alternate, trifoliate, and usually fall by harvest time.

The inflorescence is a raceme of 3–8 flowers.

Flowers are small, white or light violet, placed in leaf axils in racemes of 3–5 flowers. Self-pollination predominates; owing to closed flowering, natural hybrids are rare.

Pods have various shapes and colors, contain 1–5 seeds, and usually do not dehisce. Pods of oilseed varieties usually contain one or two seeds; pods of vegetable varieties usually contain two or three seeds.

Stems, leaves, and pods are covered with dense, stiff whitish or reddish hairs.

Seeds are round, oval, or elongated-flattened; depending on the variety, they are yellow, green, brown, or black. The mass of 1000 seeds is 100–400 g.

Food use usually correlates with seed color. Green and yellow-green seeds are produced mainly for vegetables (edible seeds). Large yellow seeds are used to make tofu (bean curd). Large black seeds are used in dishes for celebrations or other special occasions, and small flat black seeds are used to make a spicy fermented side dish. As a rule, varieties with yellow seeds are rich in oil and have relatively low protein content, whereas varieties with black seeds contain much protein and little oil. Depending on seed type, carbohydrate content can range from 15% to 25%, protein content up to 50%, and some varieties contain up to 25% oil.

Biological characteristics

Vegetation

The growing season is from 80 to 170 days.

The flowering pattern varies from strongly indeterminate to strongly determinate. The beginning of flowering depends on the variety and can vary from 80 to 150 days. The duration of flowering is from 15 to 40 days depending on the variety; in late varieties — up to 80 days.

Vegetation phases:

• emergence;
• first true leaf;
• branching;
• flowering;
• pod formation;
• ripening.

Crop rotation

In crop rotations, it is of great agronomic importance, since it is a row-crop legume with the ability for nitrogen fixation. It serves as a predecessor for spring cereals, sugar beet, potato, and in areas of insufficient moisture — for winter crops.

In crop rotation, soybean is placed after fertilized crops. In the European part of Russia, predecessors can be winter wheat, maize, and sugar beet. In the Far East — occupied fallow, and the layer and turnover of the layer of perennial grasses.

Poor predecessors are other legumes and sunflower because of common diseases.

In the Far East, soybean occupies up to 50% of the sowing area in the crop structure. According to data from the All-Russian SRI of Soybean, the optimal saturation of crop rotation is 40%, whereas at 50% seed yield decreases.

Fertilization

To form 1 t of seeds and the corresponding amount of straw, soybean consumes 80–90 kg of nitrogen, 35–40 kg of phosphorus, 60–65 kg of potassium, and 70–80 kg of calcium.

Soybean is responsive to phosphorus fertilizers. It is able to assimilate phosphorus from sparingly soluble phosphates.

Through nitrogen fixation, soybean can accumulate up to 100 kg/ha of nitrogen; thus it covers 30–60% of its nitrogen requirement. However, at the beginning of growth and development, additional application of nitrogen fertilizers is necessary.

On weakly humified soils, unlike other grain legumes, it is recommended to apply 15–60 t/ha of organic fertilizers.

A complete mineral fertilizer N_45-60P_45-120K_45-80 is applied under soybean, owing to which yield increases by 0.4–0.5 t/ha. Combined application of organic (20–25 t/ha) and mineral fertilizers is more effective.

Phosphorus-potassium fertilizers and manure are applied for fall soil cultivation; nitrogen fertilizers — in spring for cultivation. It is possible to split phosphorus-potassium fertilizers into two parts: half for fall cultivation, the remaining part — in spring for cultivation, in rows, and for top dressing.

High efficiency of local fertilizer application has been noted. Compound fertilizers are applied during sowing at a rate of 40–50 kg per ha or as top dressing in the budding phase.

Acidic soils are limed, which favorably affects the activity of nodule bacteria.

Soybean is responsive to molybdenum and boron fertilizers, which positively affect nitrogen fixation. Seeds are treated with Molybdenum fertilizers at a rate of 40–50 g of ammonium molybdate per hectare seeding rate.

Bacterial fertilizers, for example, nitragin and rhizotorfin, show high efficiency.

Soil treatment

Primary tillage for soybean in the Far East begins in late July — August. It consists of plowing to a depth of 19–22 cm with plows with skimmers and harrows. With a shallow arable layer, plowing is performed to its full depth with subsoilers. Preliminary stubble cultivation is carried out only when fields are infested with perennial weeds. Clay soils are disked.

On leveled early fallow, conditions are created for the germination of perennial weeds, which are destroyed by fallow cultivators with combined working parts for cutting and combing out weeds. Units are assembled in a train method and consist of three cultivators KPG-4 or KPS-4. Fields clean of perennial weeds are treated with disk harrows.

In the European part of Russia, after grain predecessors, 2–3 disk stubble cultivations are carried out, followed by plowing to a depth of 22–25 cm (up to 30 cm). With heavy infestation of fields by root-sprouting weeds, layer-by-layer treatment is done.

In winter, snow retention measures are provided.

In spring, harrowing of fallow is carried out. Before sowing, continuous cultivation is done with cultivators with two rows of shares for cutting weeds and two for combing them out. At the same time, the field is harrowed. Fields clean of perennial weeds are disked on the day of sowing instead of cultivating fallow. Soils strongly compacted during autumn-winter, after harrowing, are deeply loosened with non-moldboard implements while simultaneously harrowing. After that, depending on weather conditions, 1–2 cultivations are done.

An important technique in all soybean cultivation regions is leveling the field surface after plowing. With autumn leveling, in spring one limits oneself to harrowing and pre-sowing cultivation. With spring leveling, it is carried out before pre-sowing cultivation with harrowing and dragging.

If after pre-sowing cultivation the soil has become strongly loosened and dry, rolling is done with ring rollers.

Sowing

Crop care

After sowing, dry soil is rolled with ring or ring-spur rollers.

Soybean crop care includes harrowing and inter-row cultivation. Without herbicides, as a rule, one pre-emergence harrowing with light harrows and one or two post-emergence harrowings with medium tooth harrows are performed. The first post-emergence harrowing is done in the phase of formation of the first trifoliate leaf. Harrowing helps increase yield by 0.2–0.3 t/ha.

Inter-row treatment is performed with KRN-4.2 cultivators with KRN-38 weeding harrows before row closure. Depending on weed infestation, the number of inter-row treatments is 1–3.

The main soybean diseases: fusarium wilt, verticillium wilt, ash root rot, sclerotinia, alternaria. The main control methods are crop rotation and chemical means.

The main soybean pests include: mite, cutworm, soybean leaf beetle, meadow moth.

Preparations against pests

Soybean pod borer:

• Zolon, spraying during the growing season;
• Arrivo, spraying during the growing season.

Bean moth — Rogors-S, spraying during the growing season.

Pea weevil — Rogors-S, spraying during the growing season.

Pea moth — Rogors-S, spraying during the growing season.

Aphids — Rogors-S, spraying during the growing season.

Meadow moth — Arrivo, spraying during the growing season.

Polyphagous leaf beetle — Arrivo, spraying during the growing season.

Herbicides

Treflan is considered a good pre-sowing herbicide for soybean. It is applied before sowing at a rate of 1–1.5 kg a.i. per 1 ha. Following application of the herbicide, the field is harrowed. Efficiency is 70–90%.

Fields infested with cocklebur are treated with Basagran in the phase of three trifoliate leaves of the crop; the preparation consumption rate is 0.5–1 kg/ha a.i. The combination of Basagran treatment and pre-sowing application of Treflan practically eliminates the need for mechanical weed control in soybean crops.

Basagran — used against annual dicotyledonous weeds, spraying in the phase of 1–3 leaves in soybean.

Fusilade Super — against annual and perennial grass weeds, spraying crops in the phase of 4–5 leaves in soybean.

Fusilade Forte — against annual and perennial grass weeds, spraying crops in the phase of 2–4 leaves in weeds, regardless of the crop vegetation phase.

Pivot — used when growing peas for grain against annual and perennial grass weeds, spraying the soil before sowing or in the emergence phase at 2 true leaves in soybean.

Irrigation

Cultivation of soybean under irrigation, especially in the arid steppe zone of the European part of the country, makes it possible to increase yield by 1.5–2.0 times.

Optimal water regime: soil moisture at a depth of 50–70 cm should be at least 70% of the least moisture capacity at the beginning of vegetation; in the flowering and seed-filling phases — at least 80%.

The number of irrigations during the growing season is 3–5. The irrigation norm is from 300–400 to 500–600 m³/ha. The main irrigation method is sprinkling.

Harvesting

Harvesting of soybean begins when the stems and pods turn brown (in most varieties) and the leaves yellow and fall.

Because ripe pods do not dehisce (except in arid conditions), soybean can be harvested by both single-phase and two-phase methods. In dry and warm weather, direct combining is used. But more often the two-phase method is used at a low cut.

Soybean harvesting is carried out by grain harvesters at a low cut with converted headers, on which the front ring tier and support sheet are rearranged to ensure cutting of plants at a height of 4–5 cm. A stabilization mechanism is also installed on the header, the threshing drum speed is reduced to 400–450 rpm (500–600), and the optimal clearance of the threshing and separating devices of the combine is adjusted.

Post-harvest seed treatment is performed on flow grain-cleaning lines, including OVP-20A and SM-4 machines with SP-0.5 pneumatic separators and low-speed scraper elevators to separate damaged, immature, cracked, and diseased seeds and reduce crushing during cleaning. Grain is dried by active ventilation or in dryers to a moisture content of no higher than 10–12%.

Seeds are stored at a moisture content of no higher than 14%.

When growing soybean as a vegetable crop, pods are harvested when they have fully reached their size but before ripening, and when the seeds are sufficiently soft.

Varieties

Depending on the length of the growing season, soybean varieties are divided into:

• ultra-early-ripening — less than 80 days;
• very early-ripening — 81–90 days;
• early-ripening — 91–110;
• mid-early-ripening — 111–120 days;
• mid-ripening — 120–130 days;
• mid-late — 131–150 days;
• late-ripening — 151–160 days;
• very late-ripening — 161–170 days;
• exceptionally late-ripening — more than 170 days.

In Russia, mid-ripening and early-ripening varieties are most widespread. In the northern soybean cultivation regions, ultra-early-ripening varieties are promising.

Some varieties have a specific vegetable purpose, for which the seeds themselves are used, while for others sprouts obtained from germinated seed find considerable use. Seeds of some varieties are used specifically for oil production.

ARSRI S 1. The variety was developed by the All-Russian Research Institute of Soybean. Early-ripening, high yield. Resistant to lodging and pod dehiscence. Plant height from 60 to 90 cm, height of attachment of lower pods — 12–15 cm. Mass of 1000 seeds from 156 to 164 g, protein content — 37–43%, oil — 21%. Yield 2.4 t/ha. Zoned in Amur Oblast, Khabarovsk and Primorsky Krais.

Yantarnaya. The variety was developed by the All-Russian SRI of Soybean. Characterized by high adaptability to local growing conditions; does not lodge and does not dehisce at ripening. Resistant to diseases and pests. Mid-early, plant height 80 cm, attachment of lower pods — 15 cm. Mass of 1000 seeds from 160 to 190 g, protein content — 39%, oil — 20%. Yield more than 2.0 t/ha. Zoned in the Far East.

Smena. The variety was developed by the ARSRI of Soybean. Early-ripening, highly plastic. Plant height 60–65 cm, attachment of lower pods — 10–18 cm. Seeds round, yellow, mass of 1000 seeds 126–176 g, protein content — 39–42%, oil — 18–21%. Resistant to lodging and pod dehiscence. Yield 2.8 t/ha. Zoned in Amur Oblast.

VNIIMK 9186. The variety was developed by the All-Union Institute of Oil Crops. Mid-ripening, high yield. Plant height 70–90 cm, attachment of lower pods — 10–15 cm from the soil surface, mass of 1000 seeds 110–160 g, protein content — 38–43%, oil — 17–21%. Maximum yield under irrigation 4.2 t/ha. Zoned in Krasnodar Krai and Rostov Oblast.

Kirovogradskaya 4. The variety was developed by the Kirovograd Regional Agricultural Experimental Station. Mid-ripening, high-yielding. Plant height under irrigation 110–120 cm, attachment of lower pods — 15 cm from the soil surface, mass of 1000 seeds 170 g, protein content — 37–43%, oil — 17–19%. Moderately resistant to lodging. Yield under irrigation over 3.0 t/ha. Cultivated in Saratov and Astrakhan Oblasts and Kirovograd Oblast of Ukraine.

In the European part of the country, the varieties Belosnezhka, Komsomolka, Avrora, Volna, Beltskaya 25, and others are widespread.

References

1. Vavilov P. P., Gritsenko V. V., Kuznetsov V. S. et al. (1986). Plant Growing. Edited by Vavilov P. P. 5th ed., revised and enlarged. Moscow: Agropromizdat.
2. Kolomeichenko V. V. (2007). Plant Growing/Textbook. Moscow: Agrobusinesscenter.
3. Niklyaev V. S. (2000). Fundamentals of Agricultural Production Technology. Agriculture and Plant Growing. Moscow: “Bylina”.
4. Rubatzky, Vincent E., Yamaguchi, Mas. (1997). World vegetables: principles, production, and nutritive values. 2nd ed.