Effect of Fallow on Pruning Biomass and Nutrient Accumulation in Alley Croppingon Alfisols of Tropical Africa

Abstract

A study was conducted in long‐term alley cropping plots established in 1989 at International Institute of Tropical Agriculture (IITA), Ibadan, southwestern Nigeria to determine the seasonal and yearly dynamics of dry matter and nutrient concentrations of hedgerow pruning under continuous cropping and response to fallow of 1–3 years. At one year after Leucaena leucocephala transplanting, pruning was started at the 75 cm height. The pruning frequency increased from one to five times per year as trees grew. In continuous alley cropping without fertilizer application, pruning dry matter decreased gradually from a peak of 5 t ha⁻¹ at 3 years after Leucaena transplanting to about 2.5 t ha⁻¹ at 11 years after transplanting, while the ratio of dry season to wet season biomass increased. Within 5 years after establishment, nitrogen (N) and phosphorus (P) concentrations in pruning decreased and Mg increased with the continuous cropping. Fallow clearly increased pruning biomass and nutrient concentrations. At the completion of the first cycle (1993), the pruning N yield was 170 kg ha⁻¹ for the continuous cropping plot, and 269 for plots with 1 yr fallow, 344 for plots with 2 yr fallow and 241 kg ha⁻¹ for plots with 3 yr fallow. In 1993 pruning P yield increased from 6.5 to 10.9 in the continuous alley cropping and in 1995, it increased from 4.5 to 7.0 kg ha⁻¹ in one‐year fallow plots. Fallow effect on potassium (K), calcium (Ca), and magnesium (Mg) yield in pruning was also evident. These results suggest alley cropping with one‐year fallow could be an effective rotation system for nutrient cycling in Alfisols of West Africa.

^#The work was conducted when the senior author was employed by International Institute of Tropical Agriculture (IITA), PMB 5320, Ibadan, Nigeria

Keywords:

• Agroforestry
• Fallow length
• Leucaena leucocephala
• Nigeria
• Nutrient cycling

Acknowledgments

Notes

^#The work was conducted when the senior author was employed by International Institute of Tropical Agriculture (IITA), PMB 5320, Ibadan, Nigeria