Maintaining or improving the productivity of the ancient, weathered soils of eastern Uganda is a major challenge for small-scale, resource-poor farmers. Many Ugandan farmers are forced to work with soils with limited nitrogen and phosphorous availability. Often, the cost to treat soils outweighs crop profits. When farmers are unable to compensate for these losses, negative nutrient balances span from farm levels in eastern and central Uganda to sub-Saharan Africa countries. To prevent soil degradation throughout the region, better soil management is needed.
From 2003 to 2005, researchers conducted 142 on-farm trials across three semi-arid locations in eastern Uganda. Scientists report their findings on the effectiveness of five alternatives on sorghum crop systems in the May-June 2007 issue of Agronomy Journal. This research was supported by the Kawanda Agriculture Institute and INTSORMIL funded by the U.S. Agency for International Development.
With the help of local Ugandan farmers, the following management alternatives were investigated:
- Short-term fallow using mucuna, a herbaceous annual legume
- Cowpea rotation with sorghum
- Manure application
- Nitrogen and phosphorus applied as fertilizer
- Reduced tillage
Several soil fertility management practices and reduced tillage were cost effective in increasing sorghum crop yield in the region where little inorganic fertilizer is used.
"On-farm profitability and food security for sorghum production systems can be improved by use of inorganic fertilizers, manure, mucuna fallow, sorghum-cowpea rotation, and reduced tillage," said Charles Wortmann, a co-author of the study.
The most beneficial alternative practice to increasing crop output will vary according to each farmer’s situation. While manure application may be best for fields on farms that also house animals as the source of the manure, farmers who do not have the means to purchase fertilizer may profit more from the use of the cowpea-sorghum rotation or mucuna fallow.
Wortmann explained that lead author Kayuki Kaizzi worked closely with small scale farmers throughout the study to ensure that the practices evaluated were likely to be appropriate for their situations.
"The [Ugandan] farmers now participate in extension activities to inform farmers in other communities about this menu of management alternatives," said Wortmann. "This approach to research and extension takes advantage of the local knowledge of farmers, is cost-effective, and is easily replicable for addressing crop production problems of small scale farmers throughout Africa."
Wortmann and other scientists are continuing on-going studies to address the long-term sustainability of the alternative, low input practices.
Source: American Society of Agronomy