华北玉米秸秆覆盖对砂土、壤土水土保持效应的影响

Effect of Maize Straw Mulching on Water and Soil Conservation in Sandy Soil and Loam Soil of North China

通过野外径流场模拟降雨试验,研究玉米秸秆覆盖对砂土和壤土产流产沙过程的影响,探索不同土壤质地下水土保持的临界秸秆覆盖条件。处理分为2种土壤质地类型和5个水平的秸秆覆盖度：0、10%、20%、30%和40%。结果表明：壤土抗侵蚀能力优于砂土,但透水性弱于砂土;不同土壤质地条件下秸秆覆盖效益存在差异,相同的秸秆覆盖时,砂土条件下的土壤侵蚀防治效果优于壤土;2种土壤质地条件秸秆覆盖度30%时可显著提高土壤入渗总量（25.7%~33.9%）,减少产沙总量（22.2%~46.4%）,对水土流失具有良好的防治效果。考虑到过大的秸秆覆盖度（大于80%）会造成播种机堵塞,在华北保护性耕作研究实践中,建议砂土和壤土质地下的农田地表保持1 600~3 000 kg/hm2（30%~60%）的玉米秸秆覆盖,以达到较好的水土保持效果和播种质量。

Straw mulching of farmland is a main method to reduce soil erosion and to improve water retention. However,overmuch straw mulching may lower the anti-blocking capacity of no-till planter,which is important to production efficiency and seeding quality. This research aims at discussing the influence of maize straw mulching on infiltration and sediment yield process under different soil texture conditions,and concluding an appropriate straw mulching rate for the optimization of no-till planter performance as well as the conservation of water and soil in the conservation agriculture research areas of north China. A rainfall simulation experiment was carried out from October to November in 2014,and the experimental field was located at Experimental Station of China Agricultural University,in Zhuozhou City,Hebei Province,North China. The runoff monitoring site was designed as a V-shaped symmetrical distribution,composed of six experimental plots. A UGT runoff measuring device made in German was installed to monitor the runoff and sediment yield process,and maize straw was collected cut off（ less than 100 mm） after maize harvesting（ early October）. Two kind of soil type（ sandy soil and loam soil）and five kind of straw mulching rate（ 0,10%,20%,30%,40%） were considered as two independent variables in experimental design（ three repeated）. Each simulated rainfall lasted 1 h. The impacts of maize straw mulching on infiltration and sediment yield were analyzed. The results indicated that straw mulching delayed runoff time,enhanced infiltration,and reduced soil loss. Specifically,30% straw mulching treatment significantly enhanced accumulative infiltration by 25. 7% ~ 33. 9%,reduced soilloss by 22. 2% ~ 46. 4%,compared with no mulching treatment. The experimental results also showed that the erosion-resistance of soil under different texture was different： under a 1 h simulated rainfall with80 mm / h rainfall intensity,the steady infiltration rate and accumulative infiltration in loam soil were0. 02 mm / min and 5. 9 mm less than that in sandy soil condition,and the corresponding total sediment yield was less by 1 364 g compared with sandy soil. Although 10% mulching treatment under sandy soil condition reduced soil loss significantly,the total sediment yield was much greater than that of loam soil in 10% mulching treatment. So least straw mulching rate of 30% was recommended on farmland surface in sandy soil and loam soil of north China,comparing the water and soil conservation effect of straw mulching under different soil texture conditions. However,in conservation tillage fields,over mulching（ 80%） may lower the anti-blocking capacity of no-till planter,and thus affected seeding quality and grain production in north China. In conclusion,in conservation tillage system of sandy soil and loam soil planting area,30% ~ 60% maize straw mulching（ 1 600 ~ 3 000 kg / hm2） is recommended to achieve high performance of planting and high efficient soil and water conservation,which provides the valuable information for suitable straw mulching rate of maize in north China during the application of conservation tillage practice.