Namibian rangeland expert Axel Rothauge has urged communal farmers to improve soil fertility to increase mahangu production as the country enters the rainy season.
Rothauge, who works for AgriConsult, told The Namibian last week that farmers should prepare their fields early and focus on improving the quality of their soil to produce better harvests.
He says many communal farmers have cultivated the same fields for years without replacing the nutrients that crops take from the soil.
“They should start investing in soil fertility. There are fields which have been cultivated for the past 800 years and their crop yields are still increasing because soil fertility can be manipulated by man,” Rothauge says.
He says research he conducted in the Kunene and Kavango East regions found that soil in cultivated fields was less fertile than soil in nearby grazing areas.
Rothauge says the difference is that farmers have used the same fields for crop production over many years, while grazing areas have not been continuously cultivated.
He says communal farmers know the importance of applying animal manure to their mahangu fields, but many struggle to do so because of transport and other challenges.
According to Rothauge, farmers need to replace the nutrients that crops remove from the soil to maintain production.
He says artificial fertilisers can help, but they are expensive for many communal farmers.
Rothauge says most soils in Namibia’s northern communal areas are sandy, making it difficult for them to hold nutrients.
He adds that heavy rainfall can wash fertilisers through the soil before crops can absorb them.
He, therefore, advises farmers to first improve the amount of organic matter in their soil.
Organic matter, such as decomposed plants and animal manure, helps soil retain moisture and nutrients needed for crop growth.
Rothauge says farmers should focus on improving the top 30 to 40 centimetres of soil where most crop roots grow.
He says this would help the soil retain fertilisers and reduce the risk of farmers losing money when heavy rains wash nutrients away.
Rothauge also encourages communal farmers to use biochar to improve soil fertility.
Biochar is a charcoal-like material made by heating plant material with limited oxygen. Farmers can make it from materials such as weeds, branches and dry grass.
He says Namibia’s policy on conservation agriculture also recommends the use of biochar.
He says research has shown that biochar can remain active in the soil for between 50 and 100 years.
According to Rothauge, farmers may only need to apply it once because it remains in the soil for many years.
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