干旱区生态环境知识资源中心

In the Horqin Sandy Land of eastern Inner Mongolia in northern China, wind erosion in farmland is very common in a period from thawing of frozen surface soil in mid-March to sowing of crops in the end of April, largely because of dry and windy weather. However, little is known about the magnitude of wind erosion and associated nutrient losses due to erosion and the addition of nutrients by airborne dust deposition to farmlands during this period. A field experiment was conducted in an Entisol with sand origin under corn (Zea mays L.) production to investigate daily changes in wind speed and wind erosion intensity (as measured by soil transport rate) over a period from 20 March to 30 April 2001. We also measured daily rates of airborne dust deposition during the spring seasons with the high frequency of dust storm occurrence. The rates of soil transport by wind varied greatly from 13.2 to 1254.1 kg ha(-1) per day, averaging 232.1 kg ha(-1) per day, largely attributable to great variation between days in wind speed within the study period. The potential losses of nutrients through wind erosion were 0.26-24.95 kg ha(-1) per day (averaging 4.62 kg ha(-1) per day) in organic matter, 0.02-1.64 kg ha(-1) per day (averaging 0.31 kg ha(-1) per day) in nitrogen and 0.01-0.7 kg ha(-1) per day (averaging 0.13 kg ha(-1) per day) in phosphorus. The mean rates of airborne dust deposition ranged from 4.0 to 48.9 kg ha(-1) per day, averaging 19.9 kg ha(-1) per day, during the spring seasons. The potential addition of organic matter, nitrogen and phosphorus by dust input to the experimental field was, on average, 0.54, 0.04 and 0.02 kg ha(-1) per day, respectively. Although the addition was a fraction of the losses due to erosion, nevertheless, dust input in the spring seasons is one of the major suppliers of soil nutrition. The fact that the addition of nutrients by dust is about 1/10 of the losses of soil nutrients through wind erosion suggests that developing and adopting more effective management practices to reduce soil erosion losses and to improve soil fertility are crucial to achieve a sustainable agricultural system in a fragile, semiarid sandy land environment. (C) 2003 Elsevier B.V. All rights reserved.