Potentials of covercrops for sustainable short fallow replacement in low-input systems of maize production in the humid tropics

A field experiment was conducted from 1999 to 2003, in which the growth of eleven green manure covercrops were studied for biomass production at Umudike, in the humid tropics of south eastern Nigeria. The covercrops 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 Chamacrista rotundifolia, Pueraria phaseoloides, Aeschynomene histrix, Centrosema pascuorum, Centrosema brasilianum, Stylosanthes capitata, Mucuna pruriens, Mucuna deeringiana, Mucuna veracruz, Crotolaria ochroleuca, Lablab purpureus, natural grass cover and NPK fertilizer. Maize (Zea mays L.) varieties consisted of FARZ-23-Y and TZBR Eldana 2C3-W. All possible combination of the maize varieties and the manure treatment were laid out in a randomized complete block design with three replications. Mucuna deeringiana and Mucuna Veracruz gave the significantly highest biomass 3 months after planting in the establishment year. However, Aeschynomene histrix produced the significantly highest biomass 3 years after planting. Mucuna pruiens, Crotolaria ochroleuca and Lablab purpureus did not persist in competition with the native vegetation. Aeschynomene histrix fallow produced significantly higher maize dry matter yield than Centrosema pascuorum, Centrosema brasilianum, Lablab purpureus and grass cover but not other treatments. Average grain yields ranged from 1260.4kg/ha in Mucuna pruriens to 2399.4kg/ha in Aeschynomene histrix fallow in 2002 and from 640.7kg/ha in Lablab purpureus to 1428.2kg/ha in Stylosanthes capitata fallow in 2003. In 2002, grain yields obtained with Aeschynomene histrix improved fallow were statistically similar to those obtained with Chamaecrista rotundifolia, Centrosema brasilianum and NPK fertilizer treatment, but significantly lower in other cover crop fallows. There were generally no statistically significant effects of variety and its interaction with cover crops on maize crop growth and yields.Keywords: cover crops, short fallow, maize, humid tropicsGlobal Journal of Agricultural Sciences Vol. 4(2) 2005: 113-118