As a versatile legume, the soybean is a common cash crop that produces twice as much yield per acre as most other vegetables or grains, according to the Kenya Agriculture and Livestock Research Organisation (Kalro).
Soybeans make up a sizeable percentage of most human and animal foods as well as an array of non-food industrial products and fuel.
Samuel Achayo, a farmer from Siaya County occasionally grows soybeans on his farm. He says most of the seeds farmers use in the region are obtained from open-air grain markets or from a previous harvest.
A few firms such as Western Seed Company sell certified soybean seeds, but the cost is usually beyond the reach of many smallholder farmers.
The most common soybean varieties in Kenya are Nyala, Hill, Black Hawk, Gazelle and EAI 3600, which have been used in the country for a long time.
They were officially released and registered in April 2009 by the Kenya Plant Health Inspectorate Services, targeting specific growing areas.
Soybean is a warm-season crop. It does well in loamy well-drained fertile soil. Land preparation for soybean should be done by proper ploughing followed by laddering.
Soybean is best suited for areas with 300mm-1,200mm of rainfall. The soils should be deep, well-drained and with a pH of five to six.
Use recommended variety at a seed rate of 20-30 kilogrammes per acre. Plant at a depth of 2.5-5 centimetres. The soil should be adequately moist and warm when planting. Plant manually at a spacing of 45cm by 10cm. Machine planting should be at a spacing of 30cm by 15cm.
“Soybean can use atmospheric nitrogen, but that is not sufficient, so the crop is supplied with 10-15 per cent of total nitrogen requirement. Potash is required only if deficiency is observed,” said Mr Achayo.
Soybeans are usually grown under rain-fed conditions. If grown during the dry season, they require five to six irrigation cycles.
When growing soybean on a small scale, weeding can be carried out two to three times within the growing season.
Pests include cutworms, aphids, leafhoppers, antestia bugs, beetles and spider mites. These can be controlled with appropriate pesticides available from agricultural input outlets.
They include rust, wet blotch, septoria, soybean mosaic virus, fusarium, frog eye bacterial blight and charcoal rot. To control diseases, use dressed seeds for planting. Spray with appropriate fungicides if disease symptoms are spotted. Pull out diseased plants, practice crop rotation and use resistant varieties.
Soybeans are ready for harvesting when all the leaves have shed off, the pods turn brown and the seeds make a rattling sound when the plants are shaken.
Cut stems at the ground level, leave them in the sun for awhile, thresh manually when ready or store them in a well-aerated place before threshing. Mechanised harvesting can be done for erect varieties with a pod clearance above 15cm.
Yields average 800-1,200kg per hectare. According to Mr Achayo, the price per kilo ranges from Sh80 to Sh130. However, in some seasons, especially during scarcity, the prices can rise to Sh160.