“There is great potential in Zambia to increase yields to help ensure food security,” said Mulundu Mwila, PhD candidate and scientist at ZARI. “We wanted to determine the cropping systems that offered the most benefits.”
Setting up the study
For this research, ZARI and CIMMYT scientists established maize-based cropping systems trials, comprising maize monocropping, and maize-legume rotations and intercrops under both ‘conventional’ tillage, and Conservation Agriculture, across 40 farms in a variety of agroecological zones in Zambia. The team also conducted household surveys in the same communities hosting the on-farm trials to determine the share of households with enough cultivated land to benefit from the tested cropping systems.
Researchers found that the tested cropping systems produced more maize per hectare compared to non-trial host farms in the same region. The greatest positive effect uncovered was that maize-legume rotations in Zambia’s Eastern Province had the potential to increase maize yield by 1 to 2 tons per hectare, per growing season. “The Eastern Province trials showed better results because of stable and adequate rainfall amounts and distribution and because of using groundnut as a rotation crop,” said Mwila.
Researchers attributed the small effect of legumes on maize yield in the Southern Province to low levels of biomass production and nitrogen fixation, due to low and erratic rainfall, and to low residue incorporation because of livestock grazing. Conversely, the small effect of legumes on maize yield in the Northern Province might be attributed to the high rainfall amount in the region, leading to high rates of leaching of residual nitrogen during the growing season as well as the use of common beans as the preceding crop.
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