Soils are being drained of essential elements that yield the nutrient-rich grains, fruits and vegetables needed for animal and human health
Many farmers have been pushed into survival mode as rising input costs outpace farm-gate prices, forcing them to cut corners by departing from traditional good husbandry and leading to soil depletion that will hurt future generations.
Soil scientists have raised the alarm that, because farmers are not always adopting sound practices such as introducing livestock to fallow lands, crop rotation and planting cover crops such as soya beans, legumes and brassicas, this is depleting soil of essential nutrients.
Carbon and a range of elements are necessary in soil to yield nutrient rich grains, fruits and vegetables.
Part of the reason farmers are in this “survival mode” is they are “price takers and not price makers”, getting the smallest slice of the revenue pie in the supply chain. They absorb most of the risk, including diseases, pestilences and the effects of climate change, according to Francis Yeatman, an independent consultant to farmers locally and internationally.
Yeatman, himself a former farmer, said this forces producers to increasingly expand and improve yields to achieve economies of scale because input costs have risen by as much as 400% since 2014, while farm-gate prices have, at best, gone up by 100%.
“A dairy farmer has to milk 1 000 cows to make money, you won’t survive with a 400-cow herd. It is all about scale and it is wrong,” he said.
In the United Kingdom, farmers can make a good living with 300 cows because they are subsidised and get a far better 60% share of the consumer price, while South African farmers get 30% before costs are deducted.
“What we get is farmers starting to cut back on necessary inputs, on fertiliser and crop rotations, so they start farming in a survival mode, rather than a progressive or sustainable mode, and that’s where the whole problem starts,” Yeatman said.
“With proper farming, you would have crop rotations, you’d give the chance for the soil just to take a break. But they’ve been driven into a monoculture, or at the best, maybe a rotation with two or three different crops, but never a period where the soil can literally take a breather. There’s a trend towards this, it’s not wholescale in South Africa yet.”
“But probably the biggest area that we look at is soil degradation through tillage, incorrect fertiliser usage, and we’re getting massive compaction. Nutrient depletion in the soil is probably the biggest area we address now.
“The soils have deteriorated beyond belief in some cases. There are progressive farmers and many want to do the right thing but don’t have the money to do this. If we look at the trend, farmers are going into survival mode.”
Global research conducted in 1940 and again in 2004, and which has not been repeated since, showed that there had been on average 75% nutrient depletion in soils around the world, Yeatman said. The only element that increased over the period was phosphate.
He is working with a range of farmers, including macadamia nut farmers in KwaZulu-Natal and beef and sheep farmers in the Eastern Cape to “rebuild the fertility of the soil” by employing sustainable practices.
“We cannot carry on hammering our soils the way we are. I’ve just been to eSwatini and I am doing work in Zimbabwe, the two classic cases of where the soils are what we call biologically, physically and chemically bankrupt,” he said.
“If they do not put fertiliser in the soil, they will get a zero crop. There is no resilience left in those soils. Afrikaans has a wonderful saying, ‘Die grond is uitgeboer’ (the ground has been farmed out or depleted).”
Yeatman said he had been advising farmers on fertilisers to “get the balance right” but also picked up that elements like molybdenum, cobalt, selenium, iodine and nickel, which are important not only for soil and plant health but also for animal and human health, are deficient.
“These don’t necessarily come in fertilisers. We also get companies who say they’re putting an element in but it’s not a plant-available element because it is not in a form the plant can identify and absorb. It’s smoke and mirrors,” he said.
Yeatman tests the soil and advises on how to reintroduce these elements and how to farm to maintain the balance once it has been restored.
Part of the solution is to move away from full tillage, which disrupts soil structure and accelerates surface runoff and soil erosion. Tillage also reduces crop residue, which helps absorb the force of pounding raindrops and prevents soil particles from being washed away.
For livestock farmers it is important to reduce the amount of soil disturbance in pastures and plant multi-species of grasses, legumes, brassicas and herbs for grazing.
“It’s no longer a single salad. It’s not a lettuce diet. Each plant species leaks out carbohydrates into the soil, which feeds the soil biology,” he said.
“It gets exciting downstairs, what’s happening is it starts building carbon. Carbon is king, everything in the world revolves around carbon, so once you start building carbon, pastures become carbon sinks. They absorb CO2 from the atmosphere and take it into the soil through diffusion.
“We start getting more moisture held in the soils. There’s more air in the soils, and we have a thriving soil biology. This means we then can make more nitrogen available without relying on synthetic nitrogen.”
Similarly farmers growing crops such as wheat need to introduce cover crops like oats, brassicas and legumes, and introduce livestock grazing to improve soil health.
Yeatman works to get the balance right because soil depletion has affected the quality of foods available to consumers. “Two slices of bread 30 years ago would have filled your belly. Now you need to eat a loaf of bread to get the same value,” he said.
Eastern Cape Young Farmers Association chair James Miller, a fifth-generation dairy and sheep farmer in Cathcart, said he is still dealing with the effect of historical farming practices that affected soil quality.
But he said climate change is also affecting soil quality.
Productive: Independent agriculture adviser Francis Yeatman in a soil inspection pit in Zimbabwe. These soils are poor but, with the right management practices, farmers can rebuild them to become healthy.
“The main reason we have shifted to having a focus on soil health is the change in weather patterns. We are still getting 600mm of rain a year, but it is coming in bouts of 200mm at a time instead of getting gradual rain consistently throughout the year,” Miller said.
“If soils are compacted by livestock or overgrazed with no carbon on the top it’s only going to be able to hold 50% of that water. But if the soil is healthy, and there’s lots of carbon and the right soil structure, then it will be able to hold the moisture.”
Soil scientist Pieter Raath, who is an independent consultant to the fruit industry, disagrees that soil is being depleted.
“There’s a popular opinion in agriculture and often among input providers, that our soil quality is very poor and we’re degrading our soils. My opinion is different, I believe most … producers, not all of them, focus very strongly on trying to maintain good soil fertility,” he said.
“And they actually have to do that, otherwise they’re not going to get a proper crop. So they are forced to maintain the soil and that doesn’t mean that they don’t over-fertilise. A lot of them over-fertilise and waste a lot of money.”
Independent soil scientist Bennie Diedericks, who has 30 years experience in commercial farming, believes farmers “need to stop looking at products [like] fertilisers and herbicides as a solution to everything”.
“Most of the advisers in companies are wearing product glasses. They look at problems through a lens of products. They’re not necessarily looking at solving the problem.”
Part of the problem has been caused by the breakdown in farm extension services previously supported by the government’s Agricultural Research Council, Diedericks said.
He noted that it is not always easy to introduce sustainable practices such as crop rotations because planting windows are short and high input costs mean they need to make optimal use of the soil.
“When the maize comes out, the wheat goes in and you have to work the soil. You’ve only got a planting window of two or three weeks but you are hurting the soil,” Diedericks said. “The whole dynamic on a farm has changed. We’ve lost that seasonality that rests.”