【作者】 臧英；

【导师】 高焕文；

【作者基本信息】 中国农业大学 ， 农业机械化工程， 2003， 博士

【摘要】 土壤风蚀沙化已成为北方旱区农业可持续发展最为突出的问题，加强农田保护迫在眉睫。经过多年研究，我国已建立一套具有中国特色的旱地保护性耕作体系，并对保护性耕作技术和机具方面进行了大量研究，取得了显著的成果。但目前仍缺乏对保护性耕作防风蚀方面的系统研究；缺乏深入细致地对保护性耕作体系防止风蚀机理的研究；缺乏对保护性耕作体系的定量模拟研究。另外缺乏用于农田土壤风蚀观测的采沙设备的研制。针对上述问题，参照国内外经验，本文主要进行了如下研究： 1．基于国外几种风沙采集设备，结合我国实际情况研制了“中农”沙尘采集仪，其结构简单，操作方便，能够自动调整进沙口方向，能够在同一位置点采集不同高度的沙样，可以在田间进行长期的风蚀观测；在风洞内对其进行了性能校正，结果表明，沙尘采集仪满足等动力特性要求，采集率为85.6％，适用于采集以跃移形式运动的土壤颗粒。此项研究在国内尚属首次。 2．建立了免耕覆盖、耙地覆盖、免耕无覆盖和传统耕作四种处理方式的风蚀试验区，利用自行研制的沙尘采集仪、全自动气象站等测试设备，对不同耕作体系的土壤风蚀进行了系统的测定，为研究保护性耕作体系防止土壤风蚀效应及机理提供了宝贵的数据，在国内尚属首次。 试验结果表明：(1)以少免耕和秸秆覆盖相结合的保护性耕作体系可增加地表抗蚀性，明显地减少土壤风蚀。与传统翻耕相比，保护性耕作体系可增加地表土壤含水量35.6％；增加地表粗糙度265.3％，减少土壤风蚀量77.2％。(2)在秸秆覆盖和耕作两因素当中，秸秆覆盖对减小风蚀的作用最大，可减少土壤风蚀量71.2％，而且输沙量随着覆盖量的增加而减少。地表耕作的作用仅占7％，相对秸秆覆盖的影响来说不是很明显。另外，仅有免耕而没有秸秆覆盖能减少21.6％的沙尘量。(3)保护性耕作减少近地表土壤颗粒运动的数量较多，随着高度增加，保护性耕作体系减少农田土壤颗粒运动的数量相对减少。(4)保护性耕作可减少92.6％近地表吹起的大颗粒量及38.6％扬上天空的微粒量，从而可减少土壤养分损失和对大气环境的污染。 3．在对风蚀模型深入分析和田间试验的基础上，建立了针对我国保护性耕作体系的土壤风蚀模型，并利用田间试验数据进行了验证。 本模型在国外农田土壤风蚀预报模型的基础上，增加了土壤含水量对风蚀的影响。模型验证的结果表明，土壤流失量的预测值与实测结果基本吻合，初步证明所建立的保护性耕作风蚀模型是成功的。该模型以小时为步长，根据小时的气象数据、地表土壤水分、地表粗糙度及耕作管理措施，模拟不同的耕作管理体系下农田土壤风蚀流失量情况，为采取合理的农业措施防止土壤风蚀提供了依据，在国内首创。更多还原

【Abstract】 Soil wind erosion and desertification are the most important limitations to the sustainabiliry of dryland farming in Northern China. It is urgent to protect the farmland. The conservation tillage system in China has been set up, and many researches have been done with great achievements on conservation tillage technologic and machinery. However, further study is still needed to research on the effects of conservation tillage factors such as residue cover and tillage on wind erosion, to quantify and simulate the compacts of conservation tillage practices on wind erosion. In addition, the equipment used to collect the dust sample in the field is needed to develop. According to the above problems, the research achievements conducted in doctor program are listed as followed.1. Based on the several abroad samplers, the Zhong Nong dust sampler is developed. The features of the sampler are: simple structure, the ability to orientate into winds and to collect samples from various heights at the same location. Moreover, the sampler can operate during wind erosion period unattended. The test of the sampler performance is conducted in wind tunnel.The results show that the sampler satisfies the isokinetical characteristic. The trapping efficiency is about 85.6%. The sampler in its present form is suited to trap the soil particles moving in saltation.2. A field experimental plot equipped with the Zhong Nong samplers and automatic weather station is set up. The plot consists of four treatments such as no-tillage with residue cover(NTC), harrow with residue cover(NTCH), no-tillage without residue cover(NTN) and conventional moldboard plough practice(CK). The systematical experimental study on wind erosion under conservation tillage provides valuable data and feasible methodology.The results show that conservation tillage, which features more residue cover and less soil disturbance, can increase the soil water content by 35.6%, increase the surface roughness by 265.3% and reduce the soil loss of wind erosion by 77.2% compared to CK. Residue cover is more efficient for soil erosion which can reduce the soil erosion by 71.2%, comparably the surface tillage effect is less and only occupies 7%. No-tillage without residue cover can reduce the erosion by 21.6%. The conservation tillage reduces the quantity of the large soil particles moved near the surface by 92.6%, the quantity of dust emission into the atmosphere by 38.6% and the nutrient loss of the field soil.3. Based on the exiting model and the field experiment, a new wind erosion model, which assesses the impacts of conservation tillage practices on wind erosion in China, is set up and calibrated.The preliminary results show that the soil loss values calculated with model are proximally equal to those measured in the field. According to the weather data, the soil water content, surface roughness and tillage management, the field soil loss is calculated hourly under different tillage treatments, which provides information to help in finding of effective measures to reduce winderosion.更多还原