Biofertilizer gives boost to yields

More than two thousand smallholder farmers on communal land in Mashonaland, Zimbabwe are now obtaining soybean yields which are comparable to those on large commercial farms. Since 1996, Mashonaland farmers, who traditionally cultivated maize, have started soybean production and tested the effects of Rhizobium biofertilizer. Atmospheric nitrogen can only enter plants after it has been fixed in the root nodules of leguminous plants by a bacterium called Rhizobium that lives in the soil. Under natural conditions, legumes do not find the best bacteria to fix sufficient quantities of nitrogen for high yields. By inoculating seeds with Rhizobium in liquid form, yields have more than doubled in field trials. These fields performed better than fields treated with 145 kg per hectare of commercial fertiliser. At the current price levels, this means a saving of $US 50 per hectare. The International Atomic Energy Agency has been helping the Zimbabwean authorities with nitrogen-15 isotopic analysis to monitor nitrogen through the entire plant growth cycle. By this means the most efficient strains of Rhizobium can be identified and made available to farmers for a cost that can be quickly recouped in increased yields. The Soil Productivity Research Laboratory of the Ministry of Agriculture is responsible for the production of biofertilisers in Zimbabwe. The extension work on the application of the biofertiliser is done jointly with Agritex, the extension department of the Ministry of Agriculture. Contact: Dr. C. Mushambi Director of the Soil and Chemistry Research Institute Soil Productivity Research Laboratory, Private Bag 3757, Marondera, Zimbabwe. Fax: +263 4 728317More than two thousand smallholder farmers on communal land in Mashonaland, Zimbabwe are now obtaining soybean yields which are comparable to those on large commercial farms. Since 1996, Mashonaland farmers, who traditionally cultivated maize, have..