Effect of cassava-legume intercropping alternatives on crop yields and soil properties in two Agro ecological Zones of Ghana

Abstract

The research was carried out in two locations namely: Soil Research Institute, Kwadaso and Wenchi Agri. Research Institute, Wenchi. The experiment was laid out in randomized complete block design (RCBD) with three replications. Treatments in the first and second trials consisted of two factors: three levels of fertilizer (0-15-30 N-P2O5-K2O kg ha-1,), and four cassava based cropping systems. The behaviour of component crops in three row arrangements was evaluated in the third trial. Root yield was significantly affected by cropping systems at Kwadaso while fertilizer effect on root yield was observed at Wenchi. Cassava-groundnut intercrop gave the highest root yield of 70.2 t/ha at Kwadaso. The highest root yield (34.6 t/ha) at Wenchi was reported in plots treated with 15 N-P2O5-K2O k/g. The study showed higher increased in organic carbon by 39 -97% at Kwadaso and Wenchi. Total soil nitrogen decreased by 16.7%, available phosphorus by 70.8% and exchangeable potassium by 20% at Kwadaso. Increase in soil total nitrogen was reported at Wenchi. Exchangeable potassium decreased by 30% under cassava-soybean +15 N-P2O5-K2O kg/ha. Cassava showed higher values of aggressivity (1.8), relative crowding coefficient (57.4) and competitive ratio (21.4) in cassavacowpea 2:1, cassava-soybean 1:1, and cassava-cowpea 2:1 intercropping system while cowpea and groundnut showed higher values of 0.5 and 0.6 for aggressivity. In the study, intercropping system gave higher land equivalent ratio (LER). Furthermore, cassava was more productive in terms of competitive ratio when it was in association with cowpea, soybean and groundnut.