By Georgina Smith
LUSAKA, Zambia (AlertNet) - A Zambian conservation initiative that goes against conventional farming methods has tripled maize yields in some areas of the country, and shows promise both in protecting yields from extreme weather and in sequestering carbon emissions to help curb climate change, agricultural experts say.
Africa is expected to face increasing difficulty producing enough food as climate change brings more frequent droughts and floods.
But creating water-holding soil basins, reducing tilling and planting trees that help fertilize the soil may help the continent's small farmers cope, experts say.
"This is no panacea," said Dennis Garrity, World Agroforestry Centre director general. "But if this vision was applied on 50 million hectares of crop land, think of the carbon sequestration opportunities in Africa."
According to a 2005 World Wildlife Fund report, Zambia had the fourth highest level of forest loss in the world after Brazil, Indonesia and Sudan. Regular ploughing of soil for agriculture also releases tonnes of carbon into the atmosphere every year.
BUMPER CROPS AT RISK
ZambiaÂ?s farmers may just have brought in a bumper 1.9 million tonne maize harvest with some 200,000 tonnes surplus to the country's needs, but they "could not be less prepared" for an increasingly unpredictable climate said Peter Aagaard, director of ZambiaÂ?s conservation farming unit.
With more than 60 percent of Zambia's population reliant on agriculture for their income, economic prosperity in the country will depend on large part on how small-scale farmers manage their soils, he said.
"The most important principles are constant and relevant to all (crop) farmers whether they use a hoe, oxen or a tractor with satellite navigation," Aagaard said. "Reduce soil disturbance to the minimum possible, maximise soil protection to the degree possible by preserving the previous harvestÂ?s residues, and rotate" crops.
So far more than 150,000 farmers in Zambia have adopted techniques of conservation agriculture. The efforts are backed by national policy and supported by the Zambia National Farmers Union, which supports grassroots agriculture in the southern African nation.
One advantage of curbing tilling of the soil and leaving stalks and other residue of last year's harvest on top of fields is that it allows farmers to curb the amount of carbon they release.
Instead of ploughing up a whole field, holes or "basins," about 20cm deep are dug about a meter apart, and filled with compost or fertilizer as well as seed.
Every other year farmers plant them with nitrogen-fixing legumes like peanuts. The basins remain fixed year after year, and their use cuts disturbance of the soil in a field by 90 percent compared to traditional ploughing.
SPREADING OUT WORK LOWERS COSTS
According to conservation field coordinator Sinya Mbale, conservation farming allows farmers time to plan.
"Farmers can flatten their labour peak" he said, because steady work to prepare the land for the planting season can take place over a six month period. Normally farmers simply wait to hire a plough when the rains start.
Conventional farmers wait for rain to add moisture to the soil before ploughing, and often end up waiting in long queues to hire or borrow oxen, which can delay planting. Costs are also high, with plow rental typically costing $50 and tractors going for more than $180 per hectare.
"For every day we are planting late, we are losing 1.5 per cent of potential yield," Aagaard said.
In fields off the road to Chisamba outside Lusaka, rows of dark brown basins can be seen, scattered with yellow strips of last year's maize residue.
"This is part of adaptation," Mbale said. "This land preparation maintains moisture and allows water to be drawn into the soil. If there is a prolonged dry season, people will have a better crop because moisture has been maintained."
ACACIAS HELP TRIPLE YIELDS
To supplement the basins, a nitrogen-fixing acacia tree has been planted every 10 crop rows. Such trees have been used for decades in Africa's Sahel region to boost crop yields.
The tree, with an unusual seasonal cycle, sheds leaves during the rains and provides shade during the dry season. Field observations show maize yields under the tree canopy average 4.1 tonnes per hectare, compared to 1.3 tonnes beyond the canopy.
While the benefits are clear, conservation agriculture is not a quick fix. Nitrogen-fixing acacias, for instance, need to grow up to six years before benefits are felt.
"When someone is confronted with food insecurity, they need something immediate," noted Hamusimbi Coillard, head of outreach services at the Zambia National Farmers Union. "This is not an instant thing."
Only those with confidence about the future invest in building soil fertility, he said.
Lack of extension services and a land tenure system where many people do not have title to their land also hinders farmers taking up conservation agriculture, he said.
"This requires planting trees, and some (farmers) are not sure that they will stay on that land," Coillard said.
Zambia has ramped up maize production in recent years, assisted by seed and fertiliser subsidies. Coillard said that amid growing concerns about climate change, particularly predictions of more frequent and severe drought, conservation agriculture could be an important way to boost food security.
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