Performance of cassava intercropped with maize, soybean and cowpea in the forest zone of GhanaLa performance du manioc intercultive avec le maïs, le soja et le niebe dans la zone forestiere du Ghana

Abstract

Experiments were conducted in the forest zone of Ghana from 1997 to 1999 to assess the performance of two cassava varieties intercropped with maize, soybean and cowpea at different spatial arrangements. The cassava varieties were “Gblemoduade” and “Ankra” and spatial arrangements were (S1) one row cassava, one row maize, one row soybean, two rows cowpea; (S2) one row cassava, one row maize, two rows soybean, three rows cowpea; and (S3) one row cassava, one row maize, three rows soybean, four rows cowpea. Cowpea rows were planted in the minor season into cassava as a succeeding crop to maize and soybean after their harvest in the major season. Intercropping reduced root yield by 22-37% in “Gblemoduade” and 43-51% in “Ankra” compared to sole crops. “Gblemoduade”, on the average, yielded two and half times greater than Ankra under intercrop (24.8 vs 9.1 t ha^-1) and monocrop (36.9 vs 17.4 t ha^-1) as a result of larger number of roots, heavier and bigger roots than “Ankra”. Cassava yield decreased as the number of rows of soybean or cowpea increased. Root yields were similar for S2 and S3 (22.3 and 23.2 t ha^-1 for “Gblemoduade” and 8.6 and 8.9 t ha^-1 for “Ankra”, respectively), but were smaller than yields at S1 (28.8 t ha^-1 and 9.9 t ha^-1 for “Gblemoduade” and “Ankra”, respectively). “Gblemoduade” was more aggressive (a strong competitor) than “Ankra” in the system while, both cassava varieties increased in aggressivity with decreased number of soybean or cowpea rows in the mixture (i.e. S1=S2 > S3). Among the crops, maize was more competitive to cassava than soybean and cowpea. Thus, the performance of cassava can be improved by planting 1 row each of cassava, maize and soybean followed by 2 rows of cowpea (after maize and soybean harvest) and by growing the improved variety “Gblemoduade”.

Keywords: intercropping, cassava, maize, soybean, cowpea

Agricultural and Food Science Journal of Ghana Vol. 3 2004: 193-202