ScienceDaily (Apr. 14, 2007) — A little bit of manure and fertilizer can considerably improve the perspectives of Zimbabwean smallholder farmers in semi-arid regions. Nitrogen availability was found to be the factor that most limited farmers’ efforts to increase cereal yields. Dutch-sponsored researcher Bongani Ncube demonstrated this after four years of research on smallholder farms of her home country.

Ncube studied smallholder farms in the southwest of Zimbabwe. She mapped resource flows and carried out field experiments. The Zimbabwean semi-arid regions are dry and farmers face food shortages every season. Yet not water management but the supply of fertilizer, especially nitrogen, was found to be the most important factor in increasing cereal yields. Zimbabwean farmers in the semi-arid regions hardly use fertilizer and manure at present. Chemical fertilizer is expensive and manure is not readily available. Moreover, little is known about the correct use of these nutrient sources in dry climates.

Nitrogen

The main issue when cultivating soil is the nitrogen balance. Continually cultivating the same crop disrupts this balance. With field experiments, Ncube demonstrated that a little bit of basal manure, and nitrogen fertilizer added as top dressing improved the maize yield by about one-hundred percent in a good rainy season and by up to fifty percent in drier seasons.

Crop rotation

Crop rotation is another option that could provide a lot of benefit according to Ncube. This is the cultivation of different crops alternately in successive years. Leguminous crops, for example, fix nitrogen. This nitrogen remains in the soil and is taken up during the next season by sorghum, a type of grain that grows well in dry areas. Ncube proved that grain legumes can be grown successfully under the semi-arid conditions in Zimbabwe. These legumes were able to leave enough nitrogen in the ground, which doubled yields of sorghum the following season compared to sorghum-sorghum rotations. With a simulation model Ncube was once again able to show that nitrogen availability was more important in the rotation. These types of treatments often have a negative impact on water availability, yet here nitrogen was shown to be more important.

Bongani Ncube’s research was funded by NWO.

Related Stories

Scientists Discover Cost-effective Ways To Improve Crop Output In Uganda (May 17, 2007) — A team of American and Ugandan researchers worked with local farmers to test low-cost soil management alternatives in eastern Uganda. While each alternative soil treatment increased crop output, ...  > read more

Intensive Farming Is Fine For Birds And Bees, Says Report (May 11, 2008) — Eco-friendly plant and animal life have been thriving in intensively managed cereal farms alongside increasing crop yields, according to the first study of its kind. The analysis of 230 farms shows ...  > read more

Organic Farming Can Feed The World, Study Suggests (July 13, 2007) — Organic farming can yield up to three times as much food as conventional farming on the same amount of land -- according to new findings which refute the long-standing assumption that organic farming ...  > read more

Organic Corn: Increasing Rotation Complexity Increases Yields Substantially (June 1, 2008) — Researchers investigated the impact of increasing crop rotation length and complexity on crop yields in organic agricultural systems over a ten year period. They found that longer, more complex ...  > read more

Search ScienceDaily

De-Bugging Your Food