免耕对北方旱作玉米土壤水分及物理性质的影响

通过2006-2008年的田间试验，研究了北京地区免耕与传统翻耕条件下土壤水分的时空动态及其对土壤相关物理性质的影响.结果表明：研究期间，免耕和翻耕地0～100 cm土层的土壤贮水量随时间及降水变化的趋势一致，但免耕地的土壤贮水量在不同时刻以及不同降雨条件下均高于翻耕地，增幅在2.7%～30.3%，降雨相对充分条件下土壤贮水量的增量有所增加，但免耕在相对缺水的地区更值得推广；免耕地0～100 cm土层的平均土壤含水量明显高于传统翻耕，增幅在3.4%～12.8%，其中表层（0～20 cm）和底层（80～100 cm）的水分增量明显高于中间层次，最高增量可达22.2%；免耕覆盖的耕作方式可通过降低土壤容重、提高土壤孔隙度、促进土壤水稳性团聚体的形成等作用来提高土壤的保水能力和水分利用效率，进而促进作物增收.与对照相比，免耕3年后土壤水分利用率和春玉米产量分别较传统翻耕提高13.3%和16.4%.

Effects of no-tillage on soil water content and physical properties of spring corn fields in semiarid region of northern China

Field experiments were conducted in 2006-2008 to study the effects of no-tillage on the spatiotemporal dynamics of soil water content and related soil physical properties in spring corn fields in Beijing region during growth season. In study period, the water storage in 0-100 cm soil layer in tillage and no-tillage treatments had the same variation trend with time and precipitation, but the water storage at different time periods and under different precipitations was  2.7%-30.3% higher in no-tillage treatment than in tillage treatment. When the precipitation was relatively abundant, the increment of soil water storage was somewhat increased, but no-tillage was still worth to be popularized in the regions relatively deficit in precipitation. Under no-tillage, the average water storage in 0-100 cm soil layer during the three growth seasons in 2006-2008 was 3.4%-12.8% higher than that under conventional tillage, and the increment of the water storage in 0-20 cm and 80-100 cm soil layers under no-tillage was higher than that in intermediate layer, with the highest increment reached 22.2%. No-tillage improved soil water-holding capacity and water use efficiency via decreasing soil bulk density, increasing soil porosity, and promoting the formation of soil water-stable aggregates, and thereby, promoted crop yielding. After 3 years no-tillage, the soil water use efficiency and spring corn yield were increased by 13.3% and 16.4%, respectively, compared with those under convent
ional tillage.