Abstract
Much of Bangladesh has experienced land degradation due to technological change in agriculture in an attempt to increase food production. This study examines the impacts of cultivation of high‐yielding variety (HYV) rice, using power tillers, low‐lift irrigation pumps, chemical fertilizers and pesticides, on selected land and soil qualities during the period 1985–2000 in a village in southwestern Bangladesh. For the purpose, three types of land uses were identified: fields traditionally plowed to cultivate rain‐fed local aman rice using cow‐manure and very little or no pesticides; plots power tilled to cultivate rain‐fed HYV aman rice using full‐dose application of chemical fertilizers and pesticides; and fields power tilled to cultivate rain‐fed HYV aman rice followed by low‐lift pump irrigated HYV boro rice using double doses of chemical fertilizers and pesticides. Based on 120 soil samples collected from 60 plots representing these three land‐use types, the present study revealed significant changes in soil texture, bulk density and structure, increases in soil acidity and salinity, depletion of Ca, Mg, K, N, P, Zn, and organic C in double‐cropped irrigated rice fields compared to the rain‐fed single‐crop rice fields. Power‐tilled plots have shown higher rate of soil erosion and loss of soil structure than traditionally plowed fields. Low‐lift pump irrigated fields were more degraded than rain‐fed rice fields. Soil degradation has affected the yield of rice while cultivation of HYV rice has decreased the fodder production that affected livestock population. While technological change was necessary to meet the growing population demand for food, its negative impacts on land and soil qualities are alarming and should be minimized by adopting more sustainable techno‐managerial methods and continuous soil monitoring. Copyright © 2004 John Wiley & Sons, Ltd.