Green manure crops: agronomic characteristics and effect on nematodes.

Abstract

Green manure crops can improve soil health and, if chosen correctly, reduce pest and disease problems. Nineteen different cover crops were planted into nematode-infested soil in early summer 2004. These crops were grown for three months, whereafter they were destructively sampled. A similar procedure was performed with nine cover crops planted in winter 2005. Results indicated that, of the summer crops, babala, buckwheat, cowpeas, forage sorghum, Rhodes grass and velvet beans had a significantly greater per cent soil cover than sugarcane. Similarly, babala, cowpeas, Rhodes grass and velvet beans had a significantly higher aboveground biomass than sugarcane. Babala, cowpeas and tomatoes were associated with increases in Meloidogyne javanica. Ten crops significantly decreased the numbers of Pratylenchus zeae. All of the winter crops showed greater per cent soil cover than sugarcane, and six crops exhibited greater aboveground biomass. Most of the crops were associated with decreases in Pratylenchus zeae and some crops, such as giant English rape, grazing vetch, lucerne, lupins and red clover, were associated with increases in M. javanica.