Abstract:
Frequent occurrences of soil compaction damage resulting from high raindrop impact energy, and from human and animal trafficking during field operations pose a problem to farmers around the tropics. We studied the effect of some crop and soil management practices (manure, mulch, NPK applications, tillage and crop type) on some soil compactibility indices (dry bulk density, cone index, total soil porosity, gravimetric soil water content) in a Typic Paleustult in southeastern Nigeria. The study was carried out for three consecutive planting seasons using two tillage systems and four other soil management practices (poultry droppings + NPK, mulch + NPK, NPK alone and no amendment). These were laid out as split-plot in a RCB design replicated three times and using maize (Zea mays L.) and groundnut (Arachis hypogea) as test crops. Results indicate that the different soil management techniques adopted influenced dry bulk density, penetration resistance, total soil porosity and gravimetric soil water content at 44 and 66 days after planting (DAP) whereas only gravimetric soil water content was affected at 90 DAP. The dry bulk density of tilled maize and groundnut plots increased significantly (P < 0.05) by between 2 and 14% relative to no-till plots at 44 and 66 DAP. In both maize and groundnut plots, dry bulk density decreased significantly (P < 0.05) in plots amended with poultry droppings +NPK relative to the control plots by 3-10% at 44 and 66 DAP. Tilled maize and groundnut plots had 37^15% lower (P < 0.05) penetration resistance than their corresponding no-till plots at both 44 and 66 DAP. Penetration resistance measurements were lower by 16.5-25% in plots amended with poultry droppings + NPK relative to unamended plots at 44 and 66 DAP. Cumulative (1996,1997, 1998) data indicate that gravimetric soil water content in maize and groundnut plots generally increased significantly (P < 0.05) in no-till plots relative to tilled plots by 18-27% at both 44 and 66 DAP. Plots amended with poultry droppings + NPK had between 24 and 111% increase (P < 0.05) in soil gravimetric soil water content at both 44 and 66 DAP. Results are indicative that all soil compactibility indices measured were not affected at 90 DAP except for soil gravimetric soil water content in 1996 and 1998. Results from this work demonstrate that some crop and soil management practices could be used to reduce soil compactibility problems thus increasing productivity of such soil.
