Efficacy of composts on nitrogen fixation, dry root rot (Macrophomina phaseolina) intensity and yield of legumes

Abstract

 An experiment was conducted during 1995-97 to study the disease suppressive characteristics of composts. The efficacy of three composts prepared from residues of pearl millet (Pennisetum glaucum (L.) R. Br. emend. Stuntz), neem
(Azadirachta indica A. Juss.) and weeds was ascertained on nitrogen fixation, dry root rot caused by Macrophomina
phaseolin a and seed yield of clusterbean (Cyamopsis tetragonoloba (L.) Taub.) and cowpea (Vigna unguiculata (L.)
Walp). Amendment of soil with pearl millet and weed composts for two consecutive years' reduced resident population of M. phaseolina by 20-40% compared with the non-amended plots. Associated increase in antagonistic actinomycetes (28-50%) and lytic bacteria (60-70%) accounted for 20-60% reduction in plant mortality due to dry root rot in both the crops in amended plots. This resulted in higher seed yield of clusterbean (23-46%) and cowpea (13-70%). Further, amendment with composts, in general was beneficial for both the arid legumes in termS of nodulation and nitrogenase activity.