Green Manure Intercropping Systems to Boost Maize Yields: A Case Study in Kamuli District, Uganda.

Despite ongoing agricultural research and resulting improvements in crop yield on research farms, individual farms in developing countries continuing to record very low levels of production.  The objective of this study was to evaluate how the type of green manure, incorporation stage, and intercropping patterns impacted soil fertility and maize yields.  The experiment was conducted on four small-holder farms in Kamuli District in Uganda under typical farm management for two growing seasons. The field trials evaluated two green manure types (Lablab purpureus and weed mixtures), three stages of lablab incorporation (prior to flowering, after harvesting well-developed green pods, and at pod maturity harvested for yield comparison with traditional bean intercropping systems), and three intercropping patterns (relay - lablab planted and incorporated in advance of maize planting, synchronous mixed cropping - lablab planted the same day, and delayed mixed cropping - lablab planted two weeks after maize germinated).   Incorporating lablab resulted in greater yield, on average, than simply incorporating indigenous weed mixtures.  Overall, the treatments that involved incorporation of lablab increased maize yields on all the farms, while incorporation of weed mixtures decreased maize yields. Planting maize in relay with lablab gave the highest maize yields – nearly doubling the yield recorded prior to the experiment.  Planting maize synchronously with lablab decreased yields to less than obtained intercropping with weeds. This study shows that incorporating lablab as a green manure in the maize/legume intercropping systems is superior to weed mixtures or maize monoculture for increased production.  Designing the project to be farmer participatory and as an on-farm trail enabled close interaction with the farmers and a clearer understanding of some of their challenges and inputs in terms of time apportionment, labor, and practicability in adopting this alternate management technology for improving maize productivity.