Contributions of leguminous cover crops in yam production systems in Southeastern Nigeria: II. Soil Organic matter, NPK and yam yields

Field experiments were conducted between 2003 and 2006 at Umudike, Southeastern Nigeria, to evaluate ten legume cover crops for soil fertility improvement and yam production. There were twelve treatments and consisted of ten legume species ( Mucuna pruriens utilis, Mucuna pruriens IRZ, Mucuna georgia, Mucuna veracruz, Aeschynomene histrix, Pueraria phaseoloides, Stylosanthes capitata, Chamacrista rotundifolia, Centrosema pubescens and Crotolaria ochroleuca ) in comparison with natural fallow (grass cover) and natural fallow plus inorganic fertilizer NPK Mg. The experiment was a randomized complete block design with three replicates. Soil organic matter content in 2004 was significantly higher with Aeschynomene histrix than with other cover crop fallows except Pueraria phaseoloides , Crotolaria ochroleuca and Mucuna georgia. Yam tuber yields, obtained after Aeschynomene histrix fallow were significantly higher than those obtained with grass cover, inorganic fertilizer and other legume cover crop fallows except Crotolaria ochroleuca, Pueraria phaseoloides, Chamacrista rotundifolia and Mucuna pruriens IRZ.