Soybeans Production Guide

Soybeans is one of the most important crops grown in Zambia with a huge demand both locally and internationally. The crop is grown by both small-scale and commercial farmers. Agro-ecological zone II is the main producing area of the crop.

The crop has several uses including making of cooking oil, to making of stock feeds.

1. Adaptability:

Soybeans is well adapted to a wide range of soil types though deep, well drained soils are ideal. Heavy clays, compacted soils and waterlogged areas must always be avoided as the crop will perform poorly in such soils.

Soil pH range of 5.5 - 7 is ideal for good crop performance, but in instances of low pH (acidic soils like most parts of high rainfall areas of Zambia) application of lime is recommended. A soil test is necessary to determine the correct amounts of lime to apply.

Majority parts of Zambia are good for soybean production though region II (Lusaka, Eastern, Central, Copperbelt, North Western provinces) is the most ideal.

2. Variety Selection:

Variety selection is an important aspect of a successful soybean production project. Disease resistance, yield potential, lodging aspect, shattering resistance, maturity, growth habit (indeterminate or determinate), and promiscuity are all aspects a farmer needs to consider as he chooses the variety to plant.

·         Maturity: Choose a variety that matures within the growing period of your area and it must be from 110 - 120 days.

·         Shattering Resistance: Soybeans tends to shatter after maturity, spilling the beans on the ground leading to serious yield losses. Best variety is the one that stays longer in the field after maturity without shattering.

·         Yield: The variety to plant should be one that is well suited to the area and has a record of producing the highest yield in the area.

·         Lodging Aspect: A good variety needs to remain standing in the field after maturity for ease of harvesting even when combine machines are used.

·         Promiscuity: This is the ability of the soybeans to fix nitrogen with or without the aid of an inoculant. Promiscuous types will not require application of an inoculant whilst non-promiscuous types require inoculant at planting to help with nitrogen fixation. Nitrogen fixation is critical for high soybeans yields as the crop can get most of its nitrogen through the nitrogen fixing bacteria in the inoculant.

·         Disease Resistance: Soybeans tends to get affected by diseases especially where the crop is grown repeatedly and on a large scale. Choose varieties with better disease resistance to common diseases.

Zamseed has Lukanga soybeans variety, a medium maturing variety available country wide. The variety matures within 115 - 120 days. The yield potential is 4 - 4.5ton/ha and has very good disease resistance, does not shatter in the field. The variety requires inoculation since its non-promiscuous. The beans quality is quite attractive and is large seeded with a clear helium.

3. Land Preparation and Planting:

The field must be ploughed to a fine tilth of a minimum of 30cm depth. Where a hard pan exists in the field, ripping is recommended to break it. The field needs to be flat to avoid water run offs and erosion but must have good drainage to avoid waterlogging.

Soybeans must be planted at a seed rate of 90 - 110kgs/ha to achieve a good crop stand and higher yields. Planting can start late November and go on till third week of December, but one must realise that the later your planting the lower the yields and vice versa.

Plant spacing of 30 - 75cm between rows are recommended with 2 - 3cm between plants in a row. Planting in rows is recommended as it makes management of the crop a lot easier. The seed must not be planted deeper than 5cm and not in a furrow as deeper planting will impede germination.

The seed can be treated with an inoculant at planting, recommended for most of the varieties and all new fields. The inoculant can be liquid, or soil based depending on the supplier. Follow label instructions for best results.

4. Weed Management:

Soybeans do not compete well with weeds till they fully form a canopy or achieve a good crop cover. Ensure you plant in a weed free field to give the crop a good chance to grow fast with less or no competition from weeds. After achieving a good crop cover soybean manages to compete well with weeds and most weeds fail to grow as they get covered by the crop canopy, hence suffocating them.

Weeding must be done as soon as weeds are spotted. Weeding can be done by hand or use of herbicides. If herbicides are used ensure label instructions are followed with regards to time of spraying, stage of crop growth at time of spraying. There is a wide range of herbicides available on the market so ensure you get the right chemical for your purpose from your local supplier. Hand weeding can be done 2 - 3 times in the season. Great care must be taken to minimise damage to crops.

Weeding exercise must also aim at achieving a weed free field at the time of harvest to make harvesting easier and to have soybeans that are free of chaff, weeds and or weed seeds.

5. Fertilizer Application:

Soybeans is sensitive to soil acidity therefore check the soil pH (Acidity or Alkalinity). Based on soil tests lime may be necessary to raise the soil pH to desired levels of pH 5.5 - 7. Soybeans will perform fairly well on residual fertilizer from the previous crops but application of basal fertilizer like soya blend or some other basal at planting will ensure a good start for the crop before they start fixing their own nitrogen from the nodules.

Soybeans does not need nitrogen from top dressing fertilizer, its able to get the necessary nitrogen from the soil air through the nitrogen fixing process in the nodules. Because of the nitrogen fixing process, the application of inoculant to the seeds at planting is highly recommended.

Inoculants are living bacteria and need careful handling by storing them in cool places away from direct sunlight. Only apply inoculants to seeds at the time of planting and follow recommendations from the manufacturer.

6. Pests and Disease Management:

Frog eye, Red leaf blotch and rust are the most common diseases of soybeans in Zambia. Disease occurrence increases with continuous cultivation of the same crop in the same field without crop rotation.

Rust will appear like red spider mites at the bottom of leaves but when the disease has progressed it may appear like orangish to brown colour like dust has settled on the leaves. Chemical control is the best option for this disease by starting the spray program at flowering stage and spraying at 2 - 3 weeks interval. 3 sprays may be enough to achieve the desired protection.

Red leaf blotch is also another serious disease of soybeans that can greatly reduce yields. Disease resistance by the variety is the easiest way of controlling the disease and Lukanga has very good resistance to this disease.

7. Harvesting:

Harvesting of soybeans is an important operation that requires planning in advance. Delayed harvest can lead to serious loss of yields due to shattering of the pods. Harvesting can be done by hand or using a sickle or by combine.

Whichever method of harvesting is used it should achieve minimum yield losses and be economically viable.

Large fields may require use of combines to speed up the harvesting. Combining is faster but requires well trained operators to minimise losses and damage to of the machinery. The fields also need to be well levelled in order not to damage the harvesting table and not to miss some pods in uneven areas of the field. Pod clearance from the ground becomes an important aspect for the variety when combine is going to be used. Lukanga has a good ground clearance

Hand harvesting requires a lot of manpower but is ideal for smaller fields and seed crops. Workers pull the plants and thresh them on a slab or tarpaulin. The advantage of this method is the produce is of higher quality and losses tend to be lower.