沙区旱垄作对油菜生长环境的影响

垄作是沙区旱作农田常用的集水防风耕作技术。本文通过野外试验观测和土壤样品分析,对不同结构的垄作与平作下油菜生长环境进行了研究。结果表明,垄作相对于平作增加了生长季内土壤耕作层水分含量,降低了其波动幅度,改变了土壤水分在垂直剖面上的分布,使湿润锋位于耕作层,有利于油菜对土壤水分的吸收,对缓解干旱对作物生长的胁迫有积极作用。垄作下土壤易蚀性颗粒含量降低,地表粗糙度和垂直风速梯度增大,有效降低了土壤可蚀性和近地表风速,对防治土壤风蚀和保护作物幼苗有重要作用。不同结构的垄作比较,垄高15 cm、垄沟比1/12和垄高25 cm、垄沟比1/24的两种垄作在油菜生长季内集水效果较优,而垄高25 cm、垄沟比1/6的垄作在农田休闲期内防治风蚀效果较好。故结构合理的垄作是沙区旱作农田微观土地利用结构调整的有效措施。

EFFECTS OF RIDGE TILLAGE ON CROP GROWING ENVIRONMENT IN RAINFED SANDY FARMLAND

Ridge tillage is a kind of soil and water conservation tillage used frequently in the rainfed farmland of sandy areas.Through field observation and analysis of soil samples,effects of the practice were studied on growing environment of rape.The results indicate that compared with flat tillage,ridge tillage increased soil moisture of the plow layer,reduced moisture fluctuation during the growing season of rape,and altered distribution of soil moisture in the vertical profile,locating wetting front in the plow layer,which alleviated drought stress on rape growth.In addition,it also reduced the content of erodible particles in the soil,increased roughness of the land surface and vertical wind velocity grads,thus efficiently reducing soil erodibility and wind speed near the land surface,which played an important role in preventing soil wind erosion and protecting crop seedling.Comparison between various structures of ridge tillage showed ridge tillage with ridges 15 cm high and a height-spacing ratio of 1/12(T_3) and ridge tillage with ridges 25 cm high and a ratio of 1/24(T_4) did better in rainfall harvesting during the growing season of rape,while ridge tillage with ridges 25 cm high and a ratio of 1/6(T_2) did better in preventing soil wind erosion during the fallow period of cropland.So ridge tillage with a reasonable structure is an effective measure in adjusting micro-land-use structure in the rainfed farmland of sandy areas.