Learn as much as you can about the nutrient requirements of your soya crop, before you run into problems.
To some extent, your soya beans’ plant population per hectare depends on the region’s yield potential. Enough rain at the right times and suitable soil will give you a high potential for a bigger plant population.
Potential is something that can be, and usually is, unlocked by good management. Ineffective management cannot release the potential of your land no matter how good it may be.
Soya has reasonably high feed requirements and needs more phosphorus, potassium, magnesium and calcium than maize does. If nutrient levels in the soil are low, you must fertilise for a decent yield before planting.
Soya beans respond well to reserves that have built up in the soil during previous crop rotations. Band fertilising can be tricky because this crop is so sensitive to fertiliser burn.
This can often be a nutrient in short supply, and soya takes in phosphorus right up to the time when the beans make full size. The crop yield will be negatively affected if the available phosphorus is lower than 30 kg per hectare.
Phosphate needs will be taken care of if the previous crop has been well fertilised, unless you also need potassium. Too much phosphate in the soil will inhibit protein and oil content in the seed and induce zinc and iron deficiencies. It’s the old story of balance which, in one sense, is what farmers do – endlessly walk the tightrope, keeping 5 balls in the air without dropping 1.
- Single super phosphate fertilisers (supers) can be banded at 30 mm to 50 mm below and beside the seed.
- Supers provide 3 plant nutrients; phosphate, sulphur and gypsum.
- The supers will cover sulphur deficiency and tropical soils are often sulphur deficient.
- Soya beans need sulphur more than other grain crops.
- Soil sampling will tell you how much potassium to apply.
- Soya needs fairly high potassium levels when leaf canopy and stems are forming, and in the initial stages of seed formation.
- The calcium will be incorporated when you lime to correct the pH in the acid soils.
- Calcium helps to make magnesium-potassium, essential for growth, available.
- American consultant, Gary Zimmer, says: “calcium is the trucker of all minerals.”
- Deficiencies can be handled by adding manganese to fertiliser or spraying with manganese sulphate or oxide.
- Magnesium deficiency will cause yellowish leaves and cause stunting in the plants.
Cobalt (Co), molybdenum (Mo) boron (B), iron (Fe), zinc (Zn) copper (Cu)
- These trace elements are all essential parts in the spectrum of soya bean nutrient requirements.
- The doses must be precisely applied if the elements are needed because overdosing can lead to plant death – and worse, to toxic soil that will not be able to be cropped, for varying lengths of time depending on the level of toxicity.
For more information contact Kenneth Chitindi, at Pannar Seeds, firstname.lastname@example.org