THE EFFECTS OF ALLEY CROPPING AND FERTILIZER APPLICATION ON CONTINUOUSLY CROPPED MAIZE

Although alley cropping is a technology for sustained crop production, analyses of long-term trials are lacking in the literature. A trial w as conducted to study the long-term effects of alley cropping on maize under continuous cropping with and without fertilizer. Maize was plan ted twice a year for four years. Maize yields were higher with alley c ropping than without alley cropping from the fourth crop onward. Ferti lizer application increased yield for each crop. Average yields over t he eight crops were highest for the combination of alley cropping and fertilizer application. The long-term effects of the treatments on mai ze yield were estimated by regression of grain yield on time expressed as consecutive maize crops. A dummy variable was included in the mult iple regression equations to account for cropping seasons in which dro ught or other factors severely reduced yields. Without alley cropping, maize yields declined, while with alley cropping, maize yields increa sed over time. Alley cropping with moderate fertilizer use may be the best means to stabilize yield and to increase productivity where long fallow periods are no longer possible.