BULAWAYO — Smallholder maize and sorghum farmers in Zimbabwe’s semi-arid regions are harvesting more crops a hectare, thanks to a farming technique that involves applying small amounts of fertiliser.
The technique — called “microdosing” — was developed by the International Crops Research Institute for the Semi-Arid Tropics (Icrisat) to boost the efficient use of limited amounts of fertiliser to give better yields for resource-poor farmers in marginal lands.
According to Icrisat, smallholder farmers in Zimbabwe’s drier areas apply only three kilograms of nitrogen fertiliser on a hectare of farming land compared to Sub-Saharan Africa’s average rate of nine kilogrammes a hectare.
“Field trial results noted a 50 to 200% yield increase in maize and sorghum when this technique was used over many seasons compared to the conventional system used by farmers.”
A study conducted by the US-based University of Illinois College of Agricultural, Consumer and Environmental Sciences (ACES) on behalf of Icrisat which was released last month (6 March), shows that in 2011 microdosing improved food security in Zimbabwe through high crop yields at a low cost to farmers.
Research data collected in eight districts of Zimbabwe suggests a return on investment in microdosing of over 40%. The study has not yet been published in a journal.
“Our research shows that smallholder farmers’ investment in microdosing has really unlocked the power of chemical fertilisers in some of the low rainfall areas of Zimbabwe,” says Alex Winter-Nelson, the study’s co-author and a professor at ACES.
Justice Nyamangara, a Zimbabwe-based scientist at Icrisat, says poverty discourages many smallholder farmers in semi-arid areas from using fertilisers, thus resulting in low crop yields in already poor soils stripped of their fertility by years of farming.
“We have promoted the use of small amounts (25-50kg) of ammonium nitrate fertiliser a hectare using a measurement of a bottle top applied to two or three plants,” Nyamangara says.
“The technique is guided by what we call four ‘Rs’: Right source of fertiliser, right placement, right rate and right timing.”
Providing training for farmers on microdosing is vital for them to adapt the technique, he adds.
Ronald Tirivavi, a scientific officer in charge of agronomy at Icrisat, Zimbabwe, says microdosing must be linked to extension support because the quality of the season is assessed for farmers to better apply the technique.
“Field trial results noted a 50 to 200% yield increase in maize and sorghum when this technique was used over many seasons compared to the conventional system used by farmers,” Tirivavi said.
But Harjeet Singh, an India-based international coordinator of climate adaptation for ActionAid, a global organisation that fights poverty, says in addition to using fertilisers, better irrigation services and local seeds should be accessible to smallholder farmers to help boost yields and improve their livelihoods.