Effect of slope steepness and wheat crop on soil, runoff and nutrient losses in eroded land of Malakand Agency, NWFP, Pakistan.

摘要

A field experiment was conducted during 2003-05 on sloping land near Thana Malakand Agency, North-West Frontier (Pakistan) on wheat plots in comparison with bare plots. The test plots were maintained at three slope positions, i.e., top-slope (6%), mid-slope (3%) and bottom-slope (0%). The effect of both slope position and wheat crop was statistically significant on runoff, soil and nutrient losses. The respective losses of runoff and soil were 33 and 42% higher from mid-slope as compared to bottom-slope, 24 and 30% higher from top-slope as compared to mid-slope, and 49 and 59% higher from top-slope as compared to bottom-slope. Wheat crop reduced runoff losses by 60% and soil losses by 64% as compared to bare plots. The order of nutrient losses from all plots during the experimental period was: K > OM > N > Fe > P > Cu > Mn > Zn. Nutrient enrichment ratio of the sediments was greater than 1 for all the nutrients, which indicated higher losses of nutrients through surface runoff. From the effect of slope and wheat crop on soil and runoff losses, empirical equations were developed. It is concluded that increasing extent of erosion due to slope effect can further deteriorate soil properties, but to control the damaging effects of erosion, conservation strategies such as afforestation and selection of suitable crops are suggested for sustainable farming on sloping land..