Effect of slope steepness and legumes (green manure) inclusion in wheat-maize rotation on some soil properties of eroded land in Malakand Agency.

摘要

A field experiment was conducted during 2003-2004 on a slopping land in Northern NWFP near Thana, Malakand Agency, Pakistan, on plots of wheat-legume-maize rotation in comparison with bare plots to study the effect of legume green manuring on soil properties. The test plots were maintained at three slope positions, i.e. top slope (6%), mid slope (3%) and bottom slope (0%). It was observed that total N, available P and available K contents significantly increased due to incorporation of legumes as green manures. Among legumes, the maximum total N content of 0.087% was found in wheat-soybean cropping system followed by 0.04% in wheat-mungbean, 0.055% in wheat pigeonpea compared to 0.048% in wheat-wheat and 0.038% in fallow treatments. In case of P and K, wheat-soybean also contributed maximum available P (9.56 mg kg-1) and maximum available K content (135.5 mg kg-1) to the soil. All the legume treatments had significant effect and enhanced the availability of Zn, Cu, Fe and Mn in the soil. Maximum increase in organic matter content of 1.21% was recorded in wheat-mungbean treatment followed by wheat-soybean (1.20%). pH and ECe were not significantly affected and bulk density was significantly reduced by all the legume treatments as compared to fallow treatments. The reduction in bulk density may be due to increased organic matter content, increased root growth, soil aggregation and porosity. This study indicated that in order to control the damaging effects of erosion, conservation strategies such as inclusion of legumes in the conventional wheat-maize rotation may be adopted..