Rotation effects of grain and herbaceous legumes on maize yield and chemical properties of an alfisol in the Northern Guinea savanna, Nigeria

Abstract

Crop rotation with legumes and fallow has been known to enhance soil fertility and crop productivity. This prompted an investigation into the effects of some legumes and fallow on some soil chemical properties and yield of maize. The study was conducted in 2001 and 2002 on an Alfisol to determine the effects of crop rotation with grain legumes, soybean and cowpea; herbaceous legume, Centrosema pascuorum and a natural fallow on some soil chemical properties and grain yield of succeeding maize. The legumes and fallow field were established in 2001. In 2002, maize was the test crop with 0, 20, 40 and 60 kg N ha^-1 in a split-plot arrangement fitted to a randomized complete block with the legumes and fallow as the main plot and N fertilizer rates as subplot. Results showed that all legumes and fallow treatments reduced soil pH with significant (P<0.05) reduction by soybean and fallow. Only soybean treatment slightly increased soil organic carbon while cowpea, Centrosema and fallow treatments reduced it. The legumes and fallow treatments had a non-significant (P>0.05) positive total N credit. Soybean and cowpea treatments depleted while Centrosema and fallow treatments increased soil available P. The soil exchangeable Ca, Mg, K, were all decreased by the treatments. Cowpea significantly (P<0.05) depleted soil extractable Fe and Zn, Centrosema significantly (P<0.05) increased extractable Mn and soybean treatment increased non-significantly (P>0.05) extractable Mn. Maize grain yields after legumes were significantly (P<0.05) higher than after fallow. There was a high response to inorganic N fertilization by maize succeeding Centrosema and fallow. Higher soil N status after the legumes was responsible for maize yield benefit.

Keywords: crop rotation, legumes, chemical properties, alfisol

Nigeria Journal of Soil Research Vol. 6 2005: 22-31