SEQUENTIAL INTERCROPPING OF COMMON BEAN AND MUNG BEAN WITH MAIZE IN SOUTHERN ETHIOPIA

摘要

Most previous studies focused on intercropping systems involving two-crop associations. However, there is much scope to improve existing cropping systems by devising and evaluating modifications that allow more effective use of the season. To this effect, experiments were conducted to quantify efficiency of sequential intercropping consisting of maize (Zea mays L.), common bean (Phaseolus vulgaris L.) and mung bean (Vigna radiata (L.) Wilczek) during 2007 and 2009 cropping seasons, in southern Ethiopia. Treatments included three- and two-crop associations and equivalent sole crops of components. Land equivalent ratio (LER) and area time equivalency ratio (ATER) were used to estimate intercropping advantage. Maize had the highest partial LER, 0.95, whenever mung bean comes first in the sequence. Comparable partial LERs were observed in common bean irrespective of planting times while mung bean had greater partial LERs from simultaneous rather than sequential planting. Maize had the highest competitive ratio (1.56) followed by common bean (0.67) and mung bean (0.53). The three-crop association involving simultaneous planting of maize with mung bean followed by common bean (MZ + MB - CB) gave the highest mean total LER of 1.66. This combination also had the highest combined productivity and maximum monetary gain, which is above the minimum acceptable marginal rate of return. It exceeded advantages from intercrops of maize-common bean by 41% and maize-mung bean by 23%. Thus, farmers would get greater advantage from practicing sequential intercropping in areas where the season is sufficient to grow long-duration maize.