Dryland farming: How planter precision improves profitability

Malfunctions during planting can easily lead to a 10% production loss, impacting both yield and resource costs. Dr Tingmin Yu and Johan van Biljon from the Agricultural Research Council’s ARC-Agricultural Engineering Campus unpack the importance of understanding your farm plan and planter specifications. It also includes a step-by-step guide.

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In dryland farming, maize, soya, and dry beans are major crops produced by the majority of farmers on a commercial or smallholder scale. Whether using no-till or conventional farming methods, the productivity and hence the profitability of the grain crops will largely depend on planter performance.

Malfunctioning of a planter during the critical planting season can easily cost up to 10% of production in terms of reduced yield or additional seed and fertiliser cost and time spent. Planter performance is especially critical in no-till farming because of the high penetration resistance with crop residue at the soil surface, and the surface being rough as well. Inadequate planting will result in uneven seed depth and plant spacing.

Planter calibration must be done properly before planting because without calibrating the planter correctly, the correct crop seed population and thus optimal crop yield are just not achievable.

The planter calibration usually includes calibrating both the seed and fertiliser. The planter calibration, as discussed in this article, is based on a typical mechanical chain-sprocket/gear-driven maize/soy planter with a seeding disk/plate inside the seed hopper.

Know your farm plan

The following information is needed before you do calibration of a planter:

1. Target seed population per hectare.
2. Advised amount of fertiliser application in kilograms per hectare for your soil.
3. Average row distance in meters.
4. Crop cultivar seed to suit your soil and target yield.

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Know your planter

1. Thoroughly read the operational manuals and understand the recommended calibration instructions of your planter.
2. Check drive gears or sprockets and know the gear ratios from the drive wheel to seed and fertiliser hoppers.
3. Select the correct seeding plate/disk which has the proper size of holes along the disk circumference to give a seed drop with a minimum of doubles or skips.
4. Count the number of circumferential holes.
5. Understand the adjustment mechanism for fertiliser when necessary.
6. Combining drive gear ratios and the number of holes on the seeding disk/plate should give a pre-set estimated seed population and spacing.

Seed calibration in the field

1. Bring your planter with a tractor to the field side.
2. Measure a 10m distance and mark with two easily identified markers.
3. Load minimum seeds into a side unit of the seed hoppers.
4. Take the rubber/plastic seed pipe from the seed boot so that the seeds can be planted on the soil surface and easily seen.
5. Run the planter and tractor as normal planting over the 10m distance.
6. Check the furrow opening, planting depth, soil cover, and soil press to satisfaction. Make adjustments if necessary.
7. Count the number of seeds planted over the 10m distance and check any doubles or skips.

The seed population per hectare can be calculated by the following equation:

Where: a) N = planting seed population per hectare b) n = seed number counted over 10m distance c) d = average row distance in meters

Example: If the row distance is 0.9m and the seeds planted are counted as 33 over 10 meters, the planting seed population per hectare is calculated as:

Compare the calibrated results with your planned target seed population per hectare. If necessary, make adjustments by selecting a different seed disk/plate or different gear ratio and repeat the above procedure.

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Fertiliser calibration

1. Bring your tractor with planter to your field side.
2. Measure a 10m distance and identify with two easily observed markers.
3. Load minimum fertiliser into a side unit of the fertiliser hoppers.
4. Take the rubber/plastic fertiliser pipe from the fertiliser boot so that the fertiliser will be planted and easily collected by a container.
5. Run the planter and tractor as normal planting while collecting the fertiliser by a container over this 10m distance.
6. Get the weight of the fertiliser planted in grams over the 10m distance.

The fertiliser amount applied can be calculated by the following equation:

Where: a)W = fertilizer applied in kilograms per hectare; b) w = fertilizer weight in grams planted over 10m distance; c) d = row distance in meters.

Example: If the row distance is 0.9m and the fertilizer planted is collected and weighed as 140g over 10 meters, the fertilizer to be applied per hectare is calculated as:

Compare the calibrated results with your planned target fertiliser application in kilograms per hectare. If necessary, make adjustments and repeat the above procedure.

• Dr Tingmin Yu and Johan van Biljon are from the Agricultural Research Council’s ARC-Agricultural Engineering Campus. The views and opinions expressed in this article are those of the author and do not necessarily reflect the views or positions of Food For Mzansi.

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