THE technology of using small motorised no-till planters requires extensive promotion and policy support.
It will take drudgery out of agriculture and revolutionise the way small to medium scale farmers do their agriculture. Productivity will shoot up and food security will be enhanced.
Readers may note that no-till planters can also plant when the soils are dry, before rains fall or before a farmer applies irrigation water.
The crop residues are meant to protect the soil from the sun’s heat and from being eroded by rain and wind.
No till practices are part of ‘conservation agriculture’ which calls for minimum disturbance of soils to improve their structure, health and productivity.
In fields that were fallow or under a crop in the previous season, the soil can be ripped up in the dry season and then disked after the first rains to obtain a good seed bed for planting.
Ripping loosens the soil, breaking that hard pan that forms due to frequent ploughing.
Water is then able to infiltrate down, while roots also grow below the now broken plough pan to reach water and nutrients.
Ripped field soils are better able to retain moisture, especially in drought years so that crops do not readily wilt.
Again, any persistent weeds can be killed using the herbicide Round-up.
The herbicide can be mixed with other pre-emergent herbicides or spot-applied with a knapsack sprayer; it will kill existing weeds before crop emergence while the other herbicides will prevent the germination of new weeds. Because all herbicides are toxic, great care must be exercised in handling them.
So much for land preparation.
We are mixing it up with planting, but this is because the two processes are closely linked.
Let us outline planting procedures for soya bean.
This is the most critical stage of crop establishment.
Planting can be done by hand.
In this case, planting furrows are cut into the moist soil after land preparation.
Row markers and cultivators with appropriately separated tines can be used to cut planting furrows into moist soils.
Fertiliser is dribbled into the furrows at roughly a handful per metre row.
This gives a basal fertiliser rate ranging between 150 and 200kg/ha.
Seeds are dribbled into the same furrow at 15 to 20 seeds per metre row.
This gives a within row spacing of five-to-seven centimetres. The inter-row spacing can range from 30-to-50 cm.
Closer spacing is recommended for highly productive soils where adequate basal fertiliser amounts of 200-300kg/ha are applied.
Close spacing ensures full canopy cover which conserves moisture and shuts out weeds.
A high level of management is required.
Tractor-drawn machine planting is the preferred mode of planting.
Various models of precision planters are available.
They can be precisely set to give different plant populations per ha.
The seed drills allow for very close inter-row spacing; this can be increased by blocking some of the seed outlets.
They are also used for planting wheat.
Generally soya bean yields are very sensitive to population density and fertiliser rates.
Yields of five-to-seven tonnes/ha are obtainable with high populations and adequate fertiliser and moisture.
Due to equipment challenges, some farmers have resorted to broadcasting soya bean seed followed by light disking to cover the seeds and any weeds present.
In extreme cases, the soya seed has been mixed with fertiliser before broadcasting with a fertiliser spreader (vicon).
We must also talk about fertiliser application.
We have already mentioned the fertiliser spreader or vicon. Ideally basal fertiliser in soya bean lands is broadcast using a vicon or even by hand.
The reason is the crop roots are known to explore most of the soil volume in the root zone.
When fertiliser is banded as is the case with conventional planters, including ‘no-till’ ones, the plant roots encounter fertiliser only in the band.
The crop’s rooting pattern is such that most roots do not come in contact with the fertiliser throughout the growth of the crop.
This is inefficient.
Some argue spreading fertiliser all over results in losses as some will be taken up by weeds.
The counter argument is that we must control weeds so they do not steal our fertilisers.
In the next episode we shall examine the issue of crop chemicals, including herbicides.