Improved legume fallows: Influence on nitrogen and microbial dynamics, and maize (Zea mays L) grain yield in sub-humid zone of West Africa

Abstract

This study tested the effect of four improved fallow legumes; Leucaena leucophala, Cajanus cajan, Albizia lebbeck and Moringa oleifera (for 1 and 2 year period) on soil nitrogen, microbial dynamics and maize grain yield in the sub-humid zone of Ghana. The study was conducted at the University for Development Studies experimental station, at latitude 9° 25ꞌ N, longitude 0° 58ꞌ W and at 183 m asl. The layout of the experiment was a randomized complete block design (RCBD) with four replications. The pattern of decomposition for years 1 and 2 was similar, however, weight loss showed a decreasing pattern with sampling time. At 48 days, Cajanus lost 27% of its initial weight compared to Leucaena and Albizia (54%) and Moringa (94%). Albizia plots had the highest total microbial load, with bacteria being the dominant soil microorganism in all treatments. Maize yield was higher in the second year and in Albizia plot (1.72 kg/ha) while the control recorded the least yield (0.89 kg/ha) in the second year. We established that biomass amended plots improved soil N, microbial biomass and maize yield compared to control plots in both years 1 and 2. Microbial biomass and N mineralised were indicators of improved soil fertility and correlated positively with maize yield in the biomass amended plots. In conclusion, we recommend Albizia biomass as a good source of manure after 2 years of establishment under sub-humid condition.

Keywords

• decomposition
• microbial biomass
• guinea savannah
• agroforestry
• improved legume fallow