Africa: Erosion of soil fertility drops banana harvest by 50%
Investigations carried out from 2007 to 2011 in four agro-ecological regions of Rwanda and south-western Uganda looked at the impact on banana plants.
The revealed that the low levels of nutrients left in the soil was responsible for the decline in banana yields over the period. During that time 35 tonnes per ha were cultivated, instead of the more typical 70 tonnes.
Measuring the organic and mineral content of soil nutrients, the researchers found that levels of important soil minerals that sustain plant growth were low, and that the little fertility left was mainly from topsoil organic matter.
The study was carried out by Séverine Delstanche, a researcher at the Catholic University of Louvain, Belgium, and led by the International Institute of Tropical Agriculture (IITA) with funding from the Belgian government.
"Nutrient mining reduces yields, leading to food insecurity not only in rural, but also in urban areas as [lower crop surpluses] will have an impact in the cities, and prices will increase," said Piet van Asten, a systems agronomist at IITA in Uganda.
He said that the research had centred on bananas as they were a crucially important crop for food security and rural existence. As well as this there are no fertiliser recommendations in place for the region's bananas. However, bananas are not alone in suffering from the effects of low soil fertility, far from it.
Peter Okoth, a soil scientist at the International Center for Tropical Agriculture (CIAT) in Nairobi, Kenya, said that there was widespread practice amongst African farmers to pay little attention to what nutrients they were taking from the soil.
Smallholder farmers "don't return the nutrients back to the soil because they either are not aware of the change in nutrient dynamics caused by crop harvests, or don't know how to do it," he said.
Okoth added that "governments in Africa need to invest heavily in soil analysis laboratories that are manned by qualified technical people to provide advice on what is needed to make the best [use] of the soils."
Source: scidev.net
