The Sunday Mail
Peter Gambara
THIS week, most farmers are likely to be planting mostly maize as the rainy season starts in earnest. However, crop farming is like a 100-metre sprint race.
The ideal plant population in most grain producing areas of Natural Regions I, II and III is between 50 000 to 55 000 plants per hectare.f you miss one step, you will have lost the race. You might still be able to finish the race, but in an unclassified position. This week, I will concentrate on those crucial steps at planting stage that farmers should pay attention to, failure of which they will have lost the race to a good yield.
If a farmer achieves that plant population, half the job has been done. However, there are several steps at planting time that can result in the farmer failing to achieve that plant population.
The achievement of a fine tilth is one of the most important steps to achieving the desired plant population.
While some farmers start their land preparations when the ground is dry, most farmers wait for some rains before they plant.
Whatever the case, a farmer needs to achieve a fine land tilth to ensure good germination of the planted seed. Poor tilth means there are clods, weeds or dry trash on the soil surface.
Clods might sit on a germinating seed and cause it not to germinate. Weeds or trash on the surface might cause the seed not to be placed in contact with the soil and obviously a seed that is not in contact with the soil cannot germinate.
It is generally difficult to work on an uneven surface because it might be bumpy to a planter, thereby causing uneven plantings.
The weeds and trash might also clog the planter outlets, preventing it from dropping seed and fertiliser at the desired intervals. By the time you realise that the planter was not dropping seed at desired intervals, the seed will have already germinated, and you will have lost the race, within the first two weeks of the season.
In order to achieve the desired plant population, the inter row and in-row spacing need to be correct.
Nowadays, the recommendation is to move away from the traditional 90 cm inter row spacing, to much narrower 75 cm spacing.
At that inter row spacing, the in-row spacing will be 20cm in order to achieve 50 000 plants per hectare. Most seed houses pack their seed in 25kg packs for a hectare and 10kg sacks for an acre.
However, a 25kg pocket of maize seed gives approximately 50 000 kernels, while 10kg give about 20 000 kernels.
In order to achieve the desired 55 000 plants per hectare, a farmer needs to go the extra mile and add another 4 kg of seed, to give you about 58 000 kernels. At 95 percent germination or efficiency, the farmer will end up with the desired 55 000 plants per hectare (58 000 X 0,95 =55 100).
The most efficient method of planting is using a planter. At the correct calibration, a planter will give you approximately the desired plant population.
Therefore, planter calibration is key. Most farmers make the mistake of assuming that when they hire a planter from a neighbour, it is correctly calibrated. Check to see if it will achieve the desired plant population.
Farmers without access to a planter use all kinds of planting methods. Most mark out rows and use workers to drop both fertilisers and seed.
This can be one of the most inefficient planting methods, if unchecked. Workers, in general, are lazy to pick up seed that drops either too close to another seed or too far from the desired spacing.
Instead of stopping to correct it, most workers will just continue as if nothing amiss has happened.
A farmer will need a few supervisors who walk behind workers dropping seed and fertilisers to make sure they are doing the right thing.
If a worker is called back many times to correct a mistake, they will learn not to repeat the same mistakes. One of the biggest challenges with hand planting relates to covering the planted seed in furrows. I have seen farmers pulling tree branches to try and cover the seed with soil.
This method will either leave a big number of seed uncovered or might actually drag seed from its dropped position to another position, thereby distorting the spacing altogether. Farmers should always inspect how well the seed has been covered after the exercise.
One of the big mis-steps at planting relates to the application of basal fertilisers. A farmer needs to be sure of the rate of basal fertiliser that they are applying. Depending on the Natural Region, most farmers are applying 300 to 400kg per hectare.
However, most farmers find it difficult to either calibrate the planter to apply that rate or worse still when hand planting, how to determine the walking speed and application rate by the farm workers, in order to achieve the desired rate.
The trick is to continuously check as the planting progresses.
If you have just finished dropping off 25kg of seed, it means you have planted approximately one hectare, hence the fertiliser used should correspond to the desired rate per hectare.
One of the biggest mistakes farmers make at planting is the failure to apply the appropriate herbicides properly. Pre-emergent herbicides are better in controlling weeds than post emergence ones.
It is best to prevent a week from germinating, than to then try to kill it after it has already germinated.
However, some farmers fail to apply the herbicide on time, while others get the application rates completely wrong.
A pre-emergent herbicide needs to penetrate the top 1-1,5cm soil for it to be able to kill the weed seed in the soil. For that to happen, the herbicide should be applied into wet soil.
Farmers should always have their pre-emergent herbicides ready after planting such that they will apply them immediately after planting, if one planted into a wet soil or immediately after some rains, where the farmer planted into a dry soil.
Most farmers fail to control weeds because they have failed to read a herbicide label properly and therefore got the mixing completely wrong.
Most mixing rates are given per 200 litres of water that might be necessary to cover a hectare. The biggest dilemma is converting such a rate to per knapsack sprayer. If not sure, always mix the herbicide in a 200-litre drum and then ask your workers to draw and fill their knapsack sprayers from the drum.
It is better for the farmer to mix the herbicide himself/herself to be sure of the mixing ratios.
Workers have a tendency to steal chemicals at mixing point and sell them to desperate small-scale farmers next door. They will proceed to spray mostly water onto your crops, resulting in failure to control the weeds.
The speed at which the tractor or the farm worker travels whilst spraying is also critical.
A too slow speed means more chemical will be used to spray the desired area, whilst too fast a speed means the herbicide is being under applied.
Again, the trick for the farmer is always to be cross checking as the spraying takes place.
It is best to be there in person as the herbicides are mixed and sprayed, rather than tell your workers to apply herbicides to fields A, B, C, over the phone, whilst you are at home.
Therefore, as we concentrate on planting this week, make sure you have carried out the necessary steps properly.
These include achieving the correct soil tilth, correct calibration or measurement to achieve the desired spacing of the crop, as well as correct application of the basal fertiliser.
The farmer should make sure any pre-emergent herbicides are mixed properly and applied at the correct time. These operations are best carried out in the presence of the farmer or a well-trained farm manager.
If a farmer misses out on any of these important steps at planting, the chances are high that he/she will have already missed the race at the very beginning.
Peter Gambara is an agricultural economist and consultant based in Harare.
