Sugar cane and cash crop rotation helps improve soil health
Farmer's Weekly|April 16, 2021
Decades of monocropping has compromised soil health on many South African sugar cane farms, negatively affecting their productivity. Dreyer Senekal, co-director of Senekal Familie Boerdery, explains to Lloyd Phillips how he is experimenting with strategic crop rotation to improve the soil of his sugar cane enterprise.

Sugar cane was first planted in South Africa in 1848, and for most of the time since then was produced in a monocropping system. It was only in more recent years that agriculturalists and farmers began to understand the importance of biodiversity both above and below the soil surface.

As one sugar cane farmer, Dreyer Senekal, observes drily, “We used to have the view that if you needed to rotate your old sugar cane crop, you just planted a new sugar cane crop straight after it. The biggest change we might have made back then was to plant a different cane variety to the one we’d ploughed out.”

Senekal is the full-time agricultural manager of the Senekal Familie Boerdery (SFB), a diversified mega farming business established in 1978 by his father, Charl Senekal, who remains actively involved in the operations.

SFB’s agricultural enterprises cover 4 500ha of irrigated lands in Mkuze, northern KwaZulu-Natal, with water piped from Jozini Dam. The primary enterprise is sugar cane, but SFB also produces citrus, macadamia and chillies. In addition, Senekal has a small commercial beef herd that he runs as a hobby.

“Our access to irrigation and our warmer climate allows us to harvest our sugar cane every 12 months. Depending on the sugar cane variety, we get eight to 10 harvests before we plough out and replant. On average, we replant 400ha to 600ha annually on a rotational basis across our sugar cane operation. Our main varieties are N49 and N57, and we’ll soon be harvesting trials of newer varieties to see how they do. All of these varieties are specifically bred for production under irrigation,” says Senekal.

He adds that, for most of the year, the Mkuze area experiences high number of daytime heat units, about 7,5 hours of sunshine per day, an average annual temperature of 22,3°C, and a virtual absence of frost, all of which make conditions ideal for vigorous sugar cane growth.

However, irrigation is essential, given the average annual rainfall of only 550mm.

CLAY SOIL CHALLENGES

The two most common soil types in the area are Hutton and Shortlands. On the SFB farm, clay content averages a relatively high 35% to 40%, while in some parts of the farm this reaches as high as 70%. The main challenges with high-clay soils, especially in a sugar cane operation that uses heavy machinery, are surface capping and both surface and subsurface compaction.

A further challenge with SFB’s Hutton and Shortlands soils is that they tend towards an alkaline pH of 8 and above, as well as a build-up of exchangeable sodium in the deeper layers. This sodic environment exacerbates the dispersion of soil particles and the breakdown of soil aggregates, leading to compaction, run-off and erosion.

The sodium build-up became an even greater problem as drought conditions lowered Jozini Dam’s water level to 36% of capacity, thereby increasing the water’s concentration of natural sodium. However, the level of the dam is now at 56% and rising following recent rains, according to Senekal.

Continue reading your story on the app

Continue reading your story in the magazine

MORE STORIES FROM FARMER'S WEEKLYView All

Growing sweet potatoes

The sweet potato is a warm-season crop and does not fare well in cool temperatures. Implementing a crop rotation strategy is also essential to keep pests and diseases at bay.

3 mins read
Farmer's Weekly
May 14, 2021

The evolution of power in SA's agri machinery market

It is unlikely that South Africa’s commercial agriculture sector would have achieved its internationally respected status were it not for the investment that farmers have made in mechanisation. Lloyd Phillips spoke to a number of experts about some of the main agricultural machinery sales trends.

6 mins read
Farmer's Weekly
May 14, 2021

Putting crop rotation into perspective

When developing a crop rotation programme, one must take into consideration the various pests and diseases that may infect different crops in order to avoid disastrous results, says Bill Kerr.

2 mins read
Farmer's Weekly
May 14, 2021

The changing environment

The Internet of Things, where machinery and devices (often fitted with sensors) share data online, has enabled tractors and other agricultural machinery to become far more efficient and easier to operate. This, combined with mechanical innovations, is helping farmers produce more with less. Glenneis Kriel reports.

6 mins read
Farmer's Weekly
May 14, 2021

Giving farmers the advantage!

New machinery is indispensable as a support for agricultural activities during difficult times such as COVID-19, says Jaco du Preez, product specialist at CNH Industrial, distributor of New Holland in South Africa.

2 mins read
Farmer's Weekly
May 14, 2021

Breeding for efficiency adds value for this cattle farmer

Anneri Otto, who farms near Coligny in North West, never planned on becoming a farmer. However, when unfortunate circumstances forced her to take charge of her husband’s operation, she rose to the challenge, and now produces Hereford and Angus cattle, as well as pecan nuts. Pieter Dempsey reports.

5 mins read
Farmer's Weekly
May 14, 2021

Improving the stud one animal at a time

Dirco Swart, owner of Blinkmeneer Beefmasters in Frankfort, says that the future of the Beefmaster is bright, thanks to the breed’s adaptability and breeders’ passion for improvement.

4 mins read
Farmer's Weekly
May 14, 2021

Controlling biting flies

Biting flies are not only a nuisance, but can also transmit diseases and deliver painful bites, says Dr Mac.

2 mins read
Farmer's Weekly
May 14, 2021

A soya bean range for all conditions

Nico Barnard, an agronomist in the central Highveld for Pannar, explains the importance of planting different soya bean cultivars to spread risk. This is how Pannar’s soya bean range can help!

5 mins read
Farmer's Weekly
May 14, 2021

Why plants need nitrogen

This element, which is found in the chlorophyll of plants, is responsible for vegetative growth and is therefore crucial to the success of the crop.

2 mins read
Farmer's Weekly
May 07, 2021