Abstract
A field experiment was conducted during the 2001 and 2002 cropping season at the Research Farm of the Faculty of Agriculture, University for Development Studies, Tamale, Ghana. The objective of the study was to determine the appropriate crop mixture ratios for maize/soybean and sorghum/soybean cropping systems. The crop mixtures were assessed on the basis of new indices termed 'actual yield loss' (AYL) and 'intercropping advantage' (IA), and other existing indices such as land equivalent ratio (LER), relative crowding coefficient (RCC) and monetary advantage (MA). Except the three rows of maize (Zea mays cv. Okomasa) alternating with three rows of soybean (Glycine max cv. sallintuya -1), three rows of sorghum (Sorghum bicolor cv. Framida) alternating with three rows of soybean (Glycine max cv. sallintuya -1), and two rows of sorghum (Sorghum bicolor cv. Framida) alternating with three rows of soybean (Glycine max cv. sallintuya -1), intercropping reduced the yields of the component crops with respect to the pure stands. Three rows of maize (Zea mays cv. Okomasa) alternating with three rows of soybean (Sorghum bicolor cv. Framida proved to be most remunerative mixture (AYL = +0.275, IA = +0.828), followed by three rows of sorghum alternating with three rows of soybean (AYL = +0.065, IA = +0.700) and two rows of sorghum alternating with three rows of soybean (AYL = -0.344, IA = +0.171). Yield loss or gain could not be quantified by LERs and RCCs whereas AYLs and IAs indicated yield loss or gain by its sign. Therefore, AYL and IA are more appropriate when assessing yields in intercropping arrangements.
