Soyabean’s multiple benefits: A boon for Zim-ASSET


IN previous articles we have looked at practical aspects of producing a soyabean crop.
We outlined land preparation and planting routines.
We described the use of rhizobium inoculant technology as a cheap alternative to expensive top dressing nitrogen fertilisers.
Before getting lost in academic arguments, let me remind fellow farmers to spray your soyabean crops with foliar fertilisers where you can afford them.
This will boost yields.
This is particularly important if your crop was planted without basal compound fertilisers
We now examine some of the benefits of producing soyabean.
Soyabean produces the highest amount of protein per unit area compared to all other crops.
Adopting soyabean in our cropping systems will bring multiple benefits that are closely aligned with the Zim-ASSET agenda.
It will impact on food security, sustainable agricultural production, job creation and of course the whole indigenisation and empowerment agenda.
So let us explore some of these benefits in order to appreciate how soyabean should be accepted and promoted, not as minor crop, but as a strategic crop for Zimbabwe going forward.
As a soil scientist focused on soil fertility issues, my primary interest has been the deployment of legumes such as soyabeans to improve soil productivity.
Because of their ability to obtain fertilizer ‘N’ from rhizobia in the root nodules, legumes can grow in low fertility soils to give yield where maize would fail totally.
Most of the ‘N’ fixed by the rhizobia is used to make proteins in the legume plant.
Most of those proteins are stored in the seeds, making legumes rich sources of proteins for human and livestock diets.
The leaves, stems and roots of the legume also are rich in proteins. When soyabean matures, the roots all die and the leaves also fall to the ground.
This way N-rich organic matter is added to the soil, thus increasing its fertility status.
If the stems are also ploughed under, soil fertility is further improved. Research results show that when maize follows legumes like soyabean and bambarra nuts (nyimo) in a rotation, yields are higher than maize after maize.
Soyabean-wheat rotations are particularly sustainable due to this soil-improving capacity of soyabean.
The dramatic point about using Rhizobium inoculants on soyabean is that one 80-gramme (g) sachet of inoculant, costing only US$5, is enough to treat 100 kg of seed to plant one hectare.
The inoculant Rhizobium bacteria that form nodules on the soyabean roots will provide all the nitrogen that the crop will need.
If Rhizobium inoculant is not used, the farmer needs to buy 3 to 4 x 50 kg bags of ammonium nitrate (AN) fertiliser for that one hectare.
If one does the calculation, it costs between US$100 and US$140 to top dress a hectare of soyabean with ammonium nitrate (AN) fertiliser at current prices.
This is compared to US$5 worth of Rhizobium inoculant for that one hectare.
Therefore using Rhizobium inoculants represents significant cost savings for the farmer.
It is sustainable.
The ‘N’ fertiliser cost savings are important especially in an environment where limited access to agricultural inputs is reducing productivity.
While farmers are busy looking for ammonium nitrate (AN) to top dress their maize crops, soyabean crops on the other hand are receiving adequate free nitrogen fertiliser from the nodule bacteria.
And in fields where maize was planted in rotation with soyabean, top dressing fertiliser requirements are much lower.
Some farmers can do without top dressing maize in fields where soyabean crop residues were ploughed under and still get an economic yield.
Zim-ASSET requires that all of us strive find and implement cost-effective ways of increasing productivity while minimising costs.
Use of Rhizobium inoculants on soyabean crops is one such low cost strategy.
In an inaugural lecture for my professorship at the University of Zimbabwe on January 30 2014, I spoke on the issue of impact research and science in Zimbabwe’s agriculture.
I presented evidence to the effect that soyabean produces the largest quantity of protein per unit area of land among all known crops.
More importantly I argued that growing soyabean and other ‘N’-fixing legumes, was tantamount to establishing nitrogen fertiliser factories in farmers’ fields.
In the Zim-ASSET framework, crop production is one of the key result areas.
Maize and small grains (sorghum, millet, rapoko) are specifically cited as key crops.
I would argue for the inclusion of soyabean as a critical and integral component of the suite of key crops targeted by Zim-ASSET.
Soyabean is a rich source of protein for both humans and livestock. Soyabean seeds average 40 percent crude protein, 30 percent carbohydrates, 20 percent oil and 10 percent fibre.
Soyabean also contains a variety of mineral salts.
Perhaps more importantly and in the light of the HIV and AIDS pandemic, soyabean contains valuable immune-boosting chemicals that help prolong life.
Imagine if all farmers grew and processed some soyabeans for home consumption.
The health status of many citizens would significantly improve.
Soyabean can be processed at home using simple equipment, into a wide variety of foods that can substitute for expensive supermarket grocery items.
Both ‘fresh’ and ‘sour’ soya milk can be made from soyabeans.
It can also be processed into the equivalents of ‘dovi’ (peanut butter) and eggs.
Salads, relishes, fritters and various confectioneries and beverages can be made at home from soyabeans.
Fortifying our sadza or porridge with soya meal would improve the nutrition status of many families.
At one soyabean home processing workshop in Kazangarare, Hurungwe, village women were able to identify 17 grocery items that could be substituted with home processed soyabean products.
This would significantly reduce the proportion of family income allocated to those items, freeing the money to be used for other budgetary needs.
The women were able to develop new soya-based recipes.
Such is the versatility of this multipurpose soyabean.
Research shows that soyabean and maize between them provide all the essential amino acids required by the human body.
When we grow soyabean and maize and process them for home consumption, we obtain all the basic human nutritional needs.
Other foods will compliment the soya-maize base.
We must mention the 20 percent oil content of soyabean seeds.
The oil is of excellent quality, free of cholesterol.
Soya oil is used to blend with other low quality vegetable oils such as cotton seed oil for human consumption.
The oil can be converted into healthy spreads that substitute for butter and margarine.
When the oil is removed from soyabean either by solvent extraction or oil press, soya cake remains which is over 50 percent protein.
The soya cake is blended with maize meal, vitamins and mineral salts to produce livestock feeds for poultry, piggery, dairy and beef.
Texturised Vegetable Protein (TVP) derived from soyabean is used as a meat extender and meat substitute and for making a wide variety of soya-based food products.
Soya chunks, soya sausages and other preparations are available on the local market.
Soya-based products are much cheaper than animal meat products. Soyabean will provide high quality protein foods to the majority of our population who cannot afford expensive animal meat products.
In the next article, we shall examine the practical roles that soyabean can and should play in the indigenisation and economic empowerment programmes under Zim-ASSET.
Meanwhile, let us remind each other of the need for practical action. Zim-ASSET requires that we stand up and do something to address our challenges.
Our intellectuals must apply their intellects to fashion new strategies to move our economy forward.
We must have the courage to think and act outside the boxes that our colonial education packed us in.
Remember holding of workshops and conferences will not take us anywhere.


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