The soybean or soya bean is a species of legume native to East Asia, widely grown for its edible bean which has numerous uses. The plant is classed as an oilseed rather than a pulse by the UN Food and Agricultural Organization.

Climatic condition
Soybean grows well both in warm and moist climate. It grows very well at temperature of 26.5 – 30 degree C. For the rapid germination and vigorous seedling growth, the soil temperature should be maintained at 15.5 degree C or above. Most of the varieties will flower and mature quickly if grown under condition where the day length is less than 14 hours provided that the temperatures are also favorable. Generally, the soybean is planted from third week of June to first fortnight of July.

Soil

Soybean is cultivated in well drained and fertile loam soil with a pH of 6.0 to 7.5. Sodic and saline soils inhibit germination of seeds. Water logging is injurious to the crop growth.

Rotation

To make it more remunerative, soybean cropping is mixed with cropping of maize, mandua and sesamum. Mixed cropping of maize and soybean does not affect the yield of maize and at the same time also 10-12 quintals of soybean per hectare can be obtained. In mixed cropping of maize and soybean, plant maize at 100 cm row spacing keeping plant to plant distance 10 cm and three rows of soybean in between maize rows. Some of the common rotations followed are as follows:

1. Soybean – wheat
2. Soybean – potato
3. Soybean – gram
4. Soybean – tobacco
5. Soybean – potato - wheat


Cultivation

Land tillage is done in order to make the soil fragile for good germination, increase soil porosity and aeration for healthy plant growth, and kill weeds. For the best results, sample of soil is taken and analyzed. The higher the current level of nutrients in the soil, the lesser will be the quantity of fertilizer needed. The fertilizer mix containing N, P2O5 and K2O is incorporated into the soil while leveling the field at the rate of 20-30, 60 and 80 kg/ha. Irrigation of field is done 3-4 days prior to sowing to ensure sufficient moisture in the soil for good germination. Newly opened lands need Rhizobium bacteria inoculations at 10 g per kilogram of seed. This inoculation will promote nodule formation and nitrogen fixation by the plant roots. The seed is also treated with fungicides such as captan or thiram for protection against soil borne fungal diseases.


Sowing

The sowing should be done at a spacing of 45-60 cm between rows and 5-10 cm between plants depending upon seed size and season. The depth of sowing should not be more than 3-4 cm under optimum moisture condition. Usually seeding of 60-80 kg seed/ha is required to obtain a population of 4,00,000 plants per hectare. Seeds can be sown by hand or machine.


Fertilizer and Nutrient Management

For the optimum yield of soybean, 15-20 tones of farm yard manure or compost per hectare is required. A good crop of soybean yielding about 30 quintals per hectare degrades about 300 kg of nitrogen from the soil. But soybean being a legume crop has the ability to supply their own nitrogen needs provided they have been inoculated and there is efficient nodulation in the plant. An application of 20-30 kg nitrogen per hectare as a starter dose will be sufficient to meet the nitrogen requirement of the crop in the initial stage in low fertility soils having poor organic matter. Phosphorus demand starts just before the pods begin to form and continues until about ten days before the seeds are fully developed. The soil should be tested for the availability status of phosphorus to meet the requirement of the crop. With the application of phosphorus the number and density of nodules are stimulated and the bacteria become more mobile. Soybean also requires a relatively large amount of potassium than other crops. A crop of soybean yielding 30 quintals per hectare degrades about 100 kg of potassium from the soil. The rate of potassium uptake climbs to a peak during the period of rapid vegetative growth then slows down about the time the bean begins to form. Soil test is the best guide for the application of potash in the soil. In the absence of soil test, 50-60 kg K2O per hectare should be applied. The fertilizers should preferably be placed, at sowing time, about 5-7 cm away from the seed at a depth of 5-7 cm from seed level.


Irrigation

For maintaining proper soil moisture, first irrigation should be done within a week after sowing. Irrigation should be done in furrows. During excessive rains, proper drainage should be maintained. Depending upon weather and soil moisture conditions, the irrigation is continued at 10-15 days intervals until the pods are well developed.


Harvesting

It is done both by hand and mechanically. In hand harvesting, the field is first set on fire. The fire burns dry leaves, and chases or kills any lurking venomous snakes, without harming stalks and roots. Harvesters then cut the cane just above ground-level using cane knives or machetes. Mechanical harvesting uses a combine, or sugarcane harvester. This machine cuts the cane at the base of the stalk, strips the leaves, chops the cane into consistent lengths and deposits it into a transport. After that, the harvester blows the trash back onto the field. The mechanical harvesting doesn’t require the field to be set fire so remains left in the fields such as dead leaves acts as mulch for next round of planting.