Dr Jerry Dlamini has something to show his agronomy students that they will not have seen anywhere in South Africa: commercial potato fields governed by principles of a continuously covered soil and as little soil disturbance as possible, except for the spaces where tubers are planted.
© Dr Jerry Dlamini | NWUMcCain's Farm of the Future Africa was established by McCain Foods in 2022 near Lichtenburg in North West Province to promote regenerative agriculture and increase the resilience of the potato cropping system to climate change while decreasing the environmental impact of farming, including greenhouse gas emissions, crop inputs, and water use. The farm collaborates with Dr. Jerry Dlamini, senior agronomist at North West University, in measuring greenhouse gas emissions in trials and comparing regenerative agriculture with conventional farming practices.
"The farm follows a four-year rotation cycle involving four cash crops: potatoes, maize, soybeans, and wheat and cover crops," Dr Dlamini explains. "The objective is to maintain continuous soil coverage with living plants and roots for as many days as possible throughout the year, with green manures being incorporated between crop cycles to improve soil health.
Cattle grazing potato lands out-of-season
"The trial mimics how the natural ecosystem supports itself and how nutrients are recycled. When you look at current conventional systems, it's basically about tilling," he says. No one who has seen the annual intense dust storms in the Free State when the grain farms start ploughing can disagree that it presents a problem.
"So what they do in the trial is to make sure that 365 days in a year, there is soil cover. Immediately after harvesting the potatoes, they spread a cover crop mix that has your horseradish, it has sweet sorghum, it has a number of plants within the same mix."
© Dr Jerry Dlamini | NWUPost-potato cover crop mowed back to form a soil cover and release nutrients back into the soil
In conventional potato farming in South Africa, he remarks, the harvested land would lay bare throughout winter until the next planting time.
A Bladrammenas radish variety Terranova, especially bred to break the cycle of pathogenic nematodes through the exudation of various compounds decreasing their populations, forms part of this tasty mix which will then ideally, and radically for modern-day potato farms, be grazed by cattle.
"And then once they have those cover crops, they buy weaners [calves] and let them graze those cover crops. After one season of the animals grazing, which recycles the nutrients in the form of manure, they then plant potatoes again," he explains. The weaners are sold to the meat trade.
© Dr Jerry Dlamini | NWUCattle grazing where potatoes have been harvested, followed by a cover crop
Covered soil is protected soil
The second pillar is to leave the soil in peace, achieved through a specially designed tractor and harvester whose axle was adjusted to trample only on 15% of the soil surface.
Perhaps counterintuitively, the trampling of the hooves does not add to compaction but, in fact, benefits the soil. "Analysis of the soil profile shows the rooting difference between mechanically compacted and non-compacted strips. When they plough to plant the potatoes, the equipment tramples while the hooves of the cattle break the soil pan and the soil is really, really good."
Dr Dlamini, who studies the emission of the greenhouse gas nitrous oxide under agricultural conditions with international research partners, observes: "Another benefit is that when you keep soil covered, it's like having a sponge covering your soil. When you get wind, it doesn't blow away the soil. And you do not need to wait to start planting like a farmer who ploughs and opens up the soil pores to evaporation and other forms of water and nutrient loss."
© Dr Jerry Dlamini | NWUHe continues: "Cover crops lead to significant savings on water and fertilizer costs. In some fields, the combination of cover crops and livestock integration has completely eliminated the need for phosphorus and potassium applications over three years. Additionally, reduced soil erosion was evident across all fields."
Right: Dr Jerry Dlamini, senior agronomist from North West University in a soil profile hole
A recent no-till conference he attended in nearby Ottosdal convinced him that there is quite a big adoption of this system in South Africa.
"Many farmers will tell you it's an expensive system to adopt when in the actual sense it's not. Actually, you need half of the implements that a conventional farmer needs because you don't plough. You just need a no-till planter that will cut the soil and plant your grain. It's an amazing thing that they are doing there."
He invites collaboration. "We are strongly hoping that people that come to the department say, hey, we think we want to try this. They can form what we can call a regional agriculture club to help with equipment sharing."
For more information:
Dr Jerry Dlamini
School of Geo and Spatial Sciences, North West University
Tel: +27 18 389 2790
Email: Jerry.Dlamini@nwu.ac.za
https://natural-sciences.nwu.ac.za