Effects of Rhizobium inoculation and cropping systems involving common bean and lablab on water use efficiency, weeds and insects pests’ infestation

Abstract

Field experiments were conducted during two cropping seasons (2015-2016) at Selian Agricultural Research Institute (SARI) farm to determine the effect of Rhizobium inoculation and intercropping systems of maize and legumes (common bean and lablab) on soil moisture content, weeds and insect pests’ infestation. The experimental design followed a randomized complete block design (RCBD) in a 3-factorial arrangement with 4 replications per treatment. The experimental treatments consisted of 2 levels of Rhizobium inoculation (with and without rhizobia), 2 legumes (P. Vulgaris and L. purpureus) and 5 cropping systems (sole maize or sole legumes, 1 row maize to 1 row legumes (1:1) i.e. 0 m or 0.45 m of legume from maize row, 1 row maize to 2 rows of legumes (1:2) i.e. 0.1 m or 0.2 m of legumes from maize rows). The results showed that the population of the insect pests had no significant effect between the sole crop and intercrops in both seasons while from field observation, the weeds population decreased for intercrop systems compared with sole crop system. On the other hand, soil moisture content had significant effect (P≤0.001) due to Rhizobium inoculation, legumes and cropping systems in both seasons. The result showed significant (P≤0.01) interactive effect between Rhizobium and cropping systems on insect pests’ infestation in season 1. The interaction between Rhizobium, legumes and cropping systems had significant effect (P≤0.01) on soil moisture content in both seasons. These suggest further research to identify cropping systems that will decrease insect pests’ infestation, weeds and increases soil moisture content.