Influence of legume fallow on soil properties and yield of maize in South Western Nigeria

The study was conducted to investigate the influence of some legume fallows on the physico-chemical properties of soil and grain yield of maize in Southwestern Nigeria. Treatments consisting of four fallows with Mucuna utilis, Centrosema brasiliensis, Canavalia ensiformis and Cajanus cajan were planted and allowed to fallow for three years. The fallow crops were incorporated into the soil at the end of each of the three years. Maize was planted as indicator crop only at the end of the third year. Soil and plant analyses were done. Maize was harvested at maturity and grain yield calculated at 12% moisture content. Results showed that the fallow crops with exception of centrosema improved soil fertility and increased soil organic matter from 1.07% at pre-crop to 2.10, 1.90% and 1.86%, respectively on the cajanus, canavalia and mucuna plots after three years of fallow. The cation exchange capacity and phosphorus however, increased almost three fold in these fallow plots. The fallow crops positively affected nutrient concentration in leaf tissue and grain yield of maize. The coefficient of correlation (r) for N, P and K with yield was 0.93, 0.77 and 0.30 respectively. In term of effectiveness the fallow crops are rated in the following ascending order - cajanus, mucuna, canavalia, centrosema and bush. Application of NPK fertilizer (50 kg N/ha) on the plots under fallow with natural bush and centrosema gave respectively 67 and 79% yield increase compared with plots without fertilizer. There was indication that, little or no fertilizer would be required on the other treatment plots depending on targeted yield and soil test.