Comparative effects of maize-soybeans and maize-desmodium intercropping systems on yield of component crops and rainfall use efficiency in western Kenya
OSIEYO, Samuel Murunga
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Inadequate soil moisture ensuing from climate change and variability limits the effectiveness of legumes to increase maize production. Soybeans and desmodium are legumes intercropped with maize to control striga weed, improve soil fertility and prevent soil degradation. However, there exists need to determine their comparative effect on yield and rainfall use efficiency when intercropped with maize in rain-fed maize production. The main objective of this study was to compare the effect of maize-soybeans (MS) and maize-desmodium (MD) intercropping systems on yield and rainfall use efficiency in Western Kenya. The specific objectives sought to compare the effect of maize monocrop (M), MS and MD intercrops on soil moisture trends; determine effect of M, MS and MD intercrops on maize energy yield and; determine the effect of M, MS and MD intercrops on rainfall use efficiency. The study was carried in two sites in Busia and Vihiga during the planting seasons in the year 2015. This was experimental research with treatments of MS intercrop; MD intercrop; and M monocrop. Each treatment was replicated three times in RCBD arrangement. Each experimental plot measured 30 m2. Freshco 425 IR maize, Soybeans HB 19 and Greenleaf desmodium varieties were used. On site rainfall data was collected using rain gauge. Volumetric soil moisture content was measured at 7 days intervals at 5cm, 25cm and 45cm depths using theta probe type ML2X equipment. Crop yields were determined from 15m2 net plot areas by weight for maize and soybeans, and as dry matter weight for desmodium. Yield energy values were determined in kJ using bomb calorimetry to standardize yield units for maize, soyabeans and desmodium then expressed in kJ ha. -1. One-way ANOVA was performed using R software version 3.1.2 to determine whether the cropping systems had effect at 5% level of significance. Tukey Honestly significant difference was used to separate the treatment means that were significantly different. Statistically there were no significant differences in soil moisture trends in the cropping systems in season I and II at both sites. Maize energy yields were also not significantly different in both seasons in the two sites. Statistically significant differences in RUE (P<0.05) only existed in Busia site in season II in favour of intercropping. There was no yield advantage of growing maize as a single crop. Maize can be intercropping with soybeans and with desmodium at the current recommended maize population of 44,000 plants ha-1.