In conventional agriculture, the practice is to plough the land and loosen the soil before planting. But agricultural experts are warning against this method, saying that it is not sustainable for the world’s burgeoning population — which the United Nations projects will reach 8.5 billion people by 2030, from 7.3 billion currently — as it is putting a strain on land resources.

According to experts, when the plough turns the soil, it alters its structure, causing the particles to become loose and weak, and this affects yields. The situation is worsened by the effects of climate change.

In fact, periods of fallow — which were necessary to allow the soil to regenerate itself before a new crop was planted — have become non-existent, meaning yields are dropping rapidly.

Experts recommend soil management practices such as conservation agriculture, which increases productivity based on three principles — minimal soil disturbance (reduced tillage), permanent soil cover (mulching) and crop rotation.

“CA reduces production costs, is friendly to the environment, and helps to maintain high yields,” said Saidi Mkomwa, executive secretary of the Nairobi-based Africa Conservation Tillage Network.

Rudo Makunike, a sustainable land management expert at the New Partnership for Africa’s Development, (Nepad) said: “It is not only an adaptation mechanism for climate change, but it also helps to build resilience in farming systems.”

According to the United Nations Food and Agriculture Organisation, conservation agriculture reduces the farming systems’ greenhouse gas emissions and enhances its role as carbon sinks.

This is important for Africa, which according to the UN Framework Convention on Climate Change, is the most vulnerable to the effects of climate change, but the least resilient.

The impact of climate change affects all sectors of the economy — including water, energy, infrastructure, agriculture and food security, as well as tourism. The knock-on effect is lingering poverty on a continent that lags behind in meeting the UN Millennium Development Goals.

The worrying bit is that, while the land under conservation agriculture across the globe is increasing, that in sub-Saharan Africa remains a small fraction of the total.

There are at least 49.6 million hectares of land under conservation agriculture in South America and 40 million hectares in North America. Africa has a combined total of only one million hectares, according to the Africa Conservation Tillage Network.

One of the CA practises that is quickly becoming popular is zero tillage, which, according to Nepad has expanded by six million hectares across the globe in the past 10 years.

Ms Makunike said that more than 80 per cent of that land is in the Americas. “In sub-Saharan Africa, it is a mere 0.3 per cent,” she said.

Zero tillage helps to reduce soil erosion, because very little of the soil is loosened. This then speeds up the rate of soil growth, at one millimetre per year, due to the accumulation of organic matter.

Zambia has the second largest area in sub-Saharan Africa under CA after South Africa, with over 200,000 hectares. With an increasing number of Zambian farmers practising CA, agricultural yields have grown by double digits to propel the country to food security.

This is significant since just two years ago, the Zambia Vulnerability Assessment Committee noted that the number of people at risk of food insecurity in the country had risen from about 63,000 in 2012 to about 209,000. The committee attributed this to poor crop production particularly due to poor weather conditions in parts of the country.
Besides higher yields, farmers using the zero tillage method are also spending less on cultivating their land.

Saves on costs

“We just plant; we spray the weed off at the beginning and then we plant and that’s it,” said Allan Miller, a large-scale farmer in Lilayi, a region south of the capital Lusaka.

“With conservation, you use less manpower; you do about 1/3 of the work that a farmer using conventional methods does. And if you are using knapsacks for herbicides, then one person can do up to three hectares a day, which is cheaper than hiring a tractor, or the energy used in weeding by hand.”

Jane Musumina, a farmer in Zambia, also practises conservation agriculture using mukuna, a climbing plant that provides ground cover on her four hectares piece of land.

“Four years ago, I used to harvest 85 bags of maize. But now one hectare gives me 130 bags,” she said.

The mukuna reduces the rate of evaporation and keeps the soil cool. She also practices crop rotation, inter-cropping and use of shallow wells to hold water in the ground for longer.

Despite the benefits of CA, its rate of adoption in East Africa is low. Kenya has a little over 33,000 hectares under CA, mostly practised by large-scale farmers. Smallholder farmers practise partial adoption — that is a small percentage engages in crop rotation, and very few attempt zero tillage.

Stewart Baden is among the few farmers practising zero-tillage in Kenya. He grows barley on his farm in the mostly dry Machakos County to the east of Nairobi.

“The important thing about conservation agriculture is maintaining soil cover. In Kenya and in particular the areas that have black cotton soil, when it rains, it rains heavily and most of the water runs off. The best way to retain it is to maintain ground cover,” he said.

Tanzania has 25,000 hectares under CA.

The rest of East Africa also practises various methods of conservation agriculture, but no official statistics are available about the acreages involved.