THE Land Redistribution Programme afforded local farmers opportunities to acquire knowledge and become experts in producing crops they were never given an opportunity to produce before.
One such crop that local farmers are now growing is soya-bean.
Soya-bean was introduced in the country as a strategic national crop in 1976 to replace fish bone meal as the protein source in livestock feeds.
The then Rhodesian government supported soya-bean production by pegging the buying price at double the price of maize.
Since then the legume was mainly produced by white commercial farmers.
Over the past years, there has been a growing interest in producing the legume by both smallholder and large-scale commercial farmers.
The National Soya-bean Promotion Taskforce (NSPT) has also been put in place to ensure farmers have vital information to enhance their knowledge of the crop and improve quality.
Below are tips on how to produce soya-beans:
Benefits of rotation
Soya-bean is grown almost exclusively on heavy textured fertile land in the higher rainfall areas or under irrigation.
However, soya-bean can be grown on lighter textured soils.
Under dry land conditions, a soya-bean grower can produce yields of over three tonnes a hectare (ha) under good management.
It is grown mainly in rotation with maize and wheat and certain other annual crops such as cotton.
The following benefits can be realised:
l In rotation, maize yields following soya-bean have been greater than following maize at both low and high levels of nitrogen application.
l Growing soya-bean prior to maize results in better moisture conservation due to the early maturity of soya-bean.
l There is more residual nitrogen from the legume crop.
l Promotes flexibility in weed control with herbicides and in the control of certain pests and diseases.
l Soya-bean rotate particularly well with winter-irrigated wheat.
Seed Selection
Use inoculated seed.
About 70 to 90 kg certified seed will be required to get 300 000 plants a ha.
Exact requirements depend on seed size and viability.
To calculate seed requirement, it is necessary to know seed count and germination percentage and make allowances for field losses.
When choosing a variety to grow, following points are very important:
l The variety must fit in a growing season of four to four-and-half months. l Must be resistant to lodging, especially where combine harvesters are used
l Should have a longer period between physiological maturity (time when no more dry matter is added to seed) and pod shattering.
l High pod clearance to reduce losses when harvesting with a combine harvester. l Rapid stem dehydration.
l Resistance to diseases, especially red leaf blotch (Pyrenochaeta glycines) frogeye (Cercospora sojina) and soya-bean rust (Phakospora pachyrhizi).
Planting
Between mid-November and mid-December is the best time and yields fall with a crop planted in January.
This, however, depends with the amount of rainfall received in both November and December.
If good rains are received in November, yields decline with delays in planting.
However, if November receives poorer rains than December, yields are better on the December crop.
In practice, planting of longer season crops such as maize and cotton always takes precedence over soya-bean.
Planting very early may result in harvesting difficulties, as rainfall is often substantial in March whereas late plantings stand the risk of running out of water during pod-fill.
Plant population
Recommended plant population for soya-beans is 300 000 plants a ha. Plant populations not only affect yield but also lodging and pod height.
At that population, highest yields are obtained, lodging slight and pod clearance adequate.
Lower populations, especially below 200 000 plants a ha give lower yields and a reduced pod clearance (affecting harvesting using combine harvesters) and higher exceeding the recommended population reduced yield and increased lodging.
Populations of over 300 000 plants a ha can only be used with short statured varieties.
Row spacing
Recommended row spacing in soya-bean is 45 to 50 centimetres (cm).
This row spacing has 10 percent higher yield than 90 to 100 cm.
Yields in soya-bean increase depending on the amount of light intercepted by the plant.
At this row width, there is complete plant cover, which captures light hitting the ground.
However farmers prefer 75 to 90 cm as this row width allows them to use machinery in spraying herbicides, pesticides, and fungicides and allows easy access for cultivation.
It also means that seeds are closer in the row and may emerge better on capping soils.
Planting methods
With plate planters, large holes in the plates, suitable for maize planting, permit a number of seeds to fall through each hole, the seed then spreads out as it falls down the chute.
If labour is not limiting and planting on small pieces of land, use of furrowing hoes or even using the traditional hoe can help.
Whatever method is used, it is essential not to plant too deep.
Weed control
Soya-bean grows slowly during the first few weeks after planting and is very susceptible to weed competition at that stage.
Once a healthy crop has reached full canopy, especially when planted in narrow rows, it smothers most weeds.
Mechanical methods can be used but are often difficult on heavy soils in wet weather.
Herbicides may be applied using ground rigs.
Harvesting
Most of the commercial crop is harvested with combine harvesters.
Using simple hand harvesting techniques, a worker can cut, thresh and pack in clean bags.
Mechanical mowing, shelling and winnowing can increase this output.
Combine harvesters are usually used on their own but some farmers cut and windrow the crop first with swathers.
The crop is cut at physiological maturity (30 to 35 percent moisture content) when a few pods are turning brown and most of the leaves have turned yellow.
Benefits from swathing include reduced shattering losses, destruction of late weeds, faster and more extended use of scarce combines and better seed grades.
Soya-bean seed is delicate and can be easily damaged by the threshing mechanism which must be carefully adjusted and run slowly.