Alley cropping versus fertilizer

A research team from the International Institute for Tropical Agriculture (IITA) in Nigeria says that alley cropping can help maintain soil productivity, without the use of fertilizers. Alley cropping involves planting crops in 'alleys' of nitrogen-fixing plants which add nutrients to the soil. Experiments over the past six years have shown that the system can maintain maize yields at about two tonnes per hectare, without chemical fertilizer. Long-term trials were conducted on loamy, sandy soils typical of many fragile tropical soils. The tree Leucaenaleucocephalawas planted in rows four metres apart. They were regularly pruned and the leaves put on the soil; the land between the rows was planted with maize. Maize alone was planted for two years, followed by a planting of maize and cowpeas; then the three-year rotation was restarted. Results over the six years showed that when leucaena prunings were removed, and no fertilizer applied, maize yields were very low, ranging from 0.3 to one tonne per hectare. But, when the prunings were spread among the crop, yields were about two tonnes per hectare per year. The researchers estimated that the prunings supplied about 60 kg of nitrogen per hectare. When 80 kg/ha of nitrogen was applied in addition to the prunings, maize yields increased to 3.7 t/ha. In another trial, 160 kg/ha of nitrogen was applied without the prunings, and yields of maize were only 2.5 tonnes per hectare. IITA researchers will be testing alley cropping on many farms throughout Nigeria and in parts of Rwanda in cooperation with local institutions.A research team from the International Institute for Tropical Agriculture (IITA) in Nigeria says that alley cropping can help maintain soil productivity, without the use of fertilizers. Alley cropping involves planting crops in 'alleys' of..