Performance of seven crop combinations in two soils of different land-use history in eastern Nigeria

Abstract

Crop yields obtained from crop mixtures grown in a newly cleared virgin forestland were compared with those from a previously cultivated farmland to assess the crops' performance between the two sites with­out additional soil amendments. Generally a greater number of soil physicochemical properties were considered agronomically better in the forest than in the previously cultivated land. These soil properties may constitute the driving force for significantly (p£0.05) higher crop yields in the forestland and include: macroporosity, bulk density, saturated hydraulic conductivity, coarse sand content, pH, soil organic matter, total N, exchangeable acidity and Fe as well as base saturation. In both years, the high­est cassava root yields were obtained from either cassava + maize + pigeon pea or cassava + maize intercrops (not from sole cassava plots) even though the only significant (p£0.05) difference obtained was between cassava + maize + pigeon pea and all four crops combined, and at the cultivated farm­land (UNN farm) only. This suggests that it is even disadvantageous to grow cassava as a sole crop in the area. Cassava root yield reduction in 1999 relative to 1998 was higher (70%) in the UNN farm than in the forestland (40%). There was no significant difference due to crop combination on yam tuber yield in both locations in 1998. However, in 1999 sole yam plots gave significantly higher yields than cassava + yam + maize +pigeon pea plots. Increase in tuber yields was obtained in 1999 over 1998 in both locations but it was smaller ( Key words: Land use, soil properties, intercropping, land equivalent ratio Agro-Science Vol.2(2) 2001: 70-80