Varying seed and fertiliser rates cuts costs in South Africa

Peter Beneke farms 950ha of mostly dryland cropping in the Paulpietersburg area on the border of KwaZulu Natal and Mpumalanga. His farming operation, KDK Boerdery, grows maize, soybeans and corn in rotation on soils that vary greatly, due to the undulating landscape.

Variable soil

Higher lying soils are generally well drained, red in colour and low in basic cations, specifically potassium, especially in the subsoil. Lower lying soils are darker in colour, more fertile and have a greater yield potential if sufficiently drained.

He practises no-till on most of his fields to minimise soil erosion. Lime, gypsum and potash are surface applied according to prescription maps and incorporated by light disc tillage.

Photo credit: Peter Beneke

Sometimes, depending on the amounts being applied, a Vibroflex cultivator is also used to provide sufficient mixing and incorporation of fertiliser.

In addition, every third year during the winter, potash is banded prior to planting to a depth of 200 to 250mm. This has resulted in higher yields because his subsoils are inherently low in potassium and surface applied K is relatively immobile in clay soils.

Variable rate technology

All of the fertiliser containing phosphorous is banded during planting. Mr Beneke has found that by using variable rate technology when applying phosphorus he was able to reduce rates without sacrificing yield in areas with lower yield potential, where phosphorous build up has occurred over time due to a lack of plant uptake.

Yield increases and cost savings by varying planting population have, however, proven to be more difficult to achieve in his operation. Mr Beneke believes that he needs to test different cultivars at different seeding rates in different soil types on his own farm over a number of years before he can apply it with confidence to all his fields.

Planter technology

However, technology on the planter gives Mr Beneke the ability to up the seed rate on irrigated land and cut back on dryland while on the go. In some cases, both are in the same field.

This makes sense when a bag of seed costs R4,000 (£235); adjusting seeding rates is a hassle-free process because it can be done quickly from the cab of the tractor.

Another benefit is section control on the electric drive planter; this eliminates double planting in headlands, saving seed and preventing lodging. So as you can see, technology can have a valuable role in cutting costs as shown by progressive farmers like Mr Beneke.