Effects of spatial arrangement of maize (Zea mays [l.]) intercropped with common beans (Phaseolus vulgaris [l.]) and cowpeas (Vigna unguiculata [l.]) on growth and yield

Agriculture faces daunting challenges due to increasing population growth and changing food consumption patterns, natural resource scarcity, environmental degradation, climate change, and global economic restructuring. Therefore, it is necessary to adopt improved and sustainable technologies like intercropping in order to guarantee improvements in food productivity and thereby food security. Although intercropping is often recommended to farmers, specific recommendations regarding time of inter cropping and spatial arrangements for additive intercropping systems in Swaziland are scarce. A field experiment was conducted at the Malkerns Research Station, of Swaziland during 2013/2014 and 2014/2015 cropping seasons. The general objective of the study was of the improvement of maize-based cropping systems performance through increased productivity of the land on which maize is grown. The specific objectives were to determine the optimum spatial arrangement of maize for intercropping with beans and cowpeas, also to determine the better leguminous crop species for additive intercropping with maize. Treatments in the experiments included: sole maize, 1 plant/hill: sole maize, 2 plants/hill: sole maize, 3 plants/hill: sole beans: sole cowpeas: maize, 1 plant/hill, + beans: maize, 1 plan/hill, + cowpeas: maize, 2 plants/hill,+ beans: maize, 2 plants/hill + cowpeas: maize, opposite, 3 plants/hill, + beans: maize, opposite, 3 plants/hill, + cowpeas: sole maize, staggered, 3 plants/hill: maize, staggered, 3 plants/hill, + beans and maize, staggered, 3 plants/hill, + cowpeas. The design of the experiment was a randomised complete block design and treatments were replicated five times within two crop growing seasons. Data collected were on soil test results, meteorological data, data on maize, beans and cowpeas were on morphological, physiological, yield and yield components. Results showed that seed yield in maize was significantly higher (8,435 kg/ha) as a sole crop, and there was a significant difference (P < 0.01) in yield between seasons and among treatments. 2013/2014 cropping season had a higher yield of (7,873 kg/ha) compared to 2014/2015 having a yield of (7,695 kg/ha). Maize, 3 plants/hill showed to be the best optimum spatial arrangement for intercropping with beans and cowpeas in terms of growth and seed yield. Beans additively intercropped with maize were observed to be the best leguminous crop species in terms of yield for additive intercropping with maize. Maize, opposite, 3 plants/hill proved to be the desirable maize planting pattern that use resources efficient and results to higher growth rate and seed yield. In all the cropping systems, the land equivalent ratio value was greater than 1.0, indicating that intercropping was more advantageous than sole cropping system. Based on the findings of this study, it is recommended that maize farmers grow maize in association with beans (maize, opposite, 3 plants/hill) in order to obtain higher yields thus improve food production and sustainable crop production adapting to climate change in Swaziland.