Shifting paradigms to make SA sugar cane farming more sustainable

The negative effects of more than 170 years of monocropping with sugar cane in South Africa are starting to appear. KwaZuluNatal sugar cane farmer Deon Schröder explains what these are, why they should be changed, and how he is going about this on his farm.

- Lloyd Phillips

Sugar cane (Saccharum officinarum) is a perennial crop that can be harvested a number of times once first growth and regrowth have reached maturity.

Deon Schröder, who farms in KwaZulu-Natal’s Dalton area, grows 600ha of dryland sugar cane, of which about 55% is harvested in an 18to 24-month rotation.

“We get roughly five harvests from a field, which means we plough out and replant a field every 10 years,” he says.

“Traditionally, a field would lie fallow for three to six months between ploughing out and replanting. Like many other South African sugar cane growers, I struggle with an increase in soil acidity over the life of a field. Even though sugar cane can tolerate soil acidity to some degree, it’s commonly a severely limiting factor, resulting in serious yield losses.”

SOIL ACIDITY

South Africa’s sugar cane farmers typically deal with increased soil acidity by applying lime or gypsum to the surface of a fallow land immediately after a crop plough-out.

According to Schröder, most sugar cane farmers aim to keep their lands totally free of weeds, using herbicides as well as hoes.

In addition, they use chemical fertilisers to boost growth. Based on soil test results, a fertiliser mix is applied at a rate of about 120kg/ha nitrogen (N), 20kg/ ha phosphorus (P) and 200kg/ha potassium (K). Ratoon crops are given the same mix, but a slightly higher rate of N – between 140kg/ha and 180kg/ha.

“When a field is ready for harvesting, we burn it to remove as much leafy material as possible from the standing stalks to make harvesting and processing easier,” says Schröder.