Potential of cover crops for short fallow replacement in low-input systems of maize production in the humid tropics

摘要

A field experiment was conducted from 1999 to 2003, in which the growth of eleven green manure cover crops were studied for biomass production at Umudike, in the humid tropics of south eastern Nigeria. The cover crops were turned into the soil as green manures after three years of fallow and compared with grass cover and NPK fertilizer for production of two maize varieties. Treatments comprised Chamaecrista rotundifolia, Pueraria phaseoloides, Aeschynomene histrix, Centrosema pascuorum, C. brasilianum, Stylosanthes capitata, Mucuna pruriens, M. deeringiana, M. veracruz, Crotolaria ochroleuca, Lablab purpureus, natural grass cover and NPK fertilizer. Maize (Zea mays L.) varieties consisted of FARZ-23-Y obtained from National Seed Service, Umudike and TZBR Eldana 2C3 - W from IITA, Ibadan, Nigeria. All possible combinations of the maize varieties and the manure treatments were studied. M. deeringiana and M. veracruz gave the significantly highest biomass 3 months after planting in the establishment year. However, A. histrix produced the highest biomass 3 years after planting. M. pruriens, C. ochroleuca and L. purpureus did not persist in competition with the native vegetation. A. histrix fallow produced higher maize dry matter than C. pascuorum, C. brasilianum, L. purpureus and grass cover but not other treatments. Average grain yields ranged from 1260.4kg/ha after M. pruriens to 2399.4 kg/ha after A. histrix fallow in 2002 and from 640.7kg/ha after L. purpureus to 1428.2kg/ha after S. capitata fallow in 2003. In 2002, grain yields obtained after A. histrix improved fallow were statistically similar to those obtained after C. rotundifolia, C. brasilianum and NPK fertilizer treatments, but significantly lower in other covercrop fallows. There were generally no statistically significant effects of variety and its interaction with covercrops on maize crop growth and yields