Effects Of Different Tillage Managements On Soil Temperature Of Dry Farmland In Semi-arid Hilly Areas Of Loess Plateau

This paper compared the effects of different plastic film mulch in two ridges and the furrow, different plastic film mulch in flat farmland, different amount of nitrogen fertilizer and different amount of straw(applied at5cm below the soil surface before planting), different previous crops on soil temperature of dry farmland at different depths below the soil surface respectively or together, quantified the changes of soil temperature under these managements and analyzed the relationship between soil temperature and air temperature in semi-arid hilly areas of Loess Plateau. All these treatments are widely used in local farm. The aim of this research was to provide the support for the establishment of the plant-soil model to predict the effects of global change on the local crops. Some field experiments were conducted and a few major findings were achieved as follows:(1) Plastic film mulch had a good warming effects on soil temperature in bare two ridges and the furrow, and it increased the soil temperature5cm or10cm below the soil surface by an average of3.5℃in furrows and4℃in ridges. The warming effects of the plastic film mulch was bigger in the early period, and it gradually reduced as the mulching time increased.(2) The soil temperature of the maize land which grew alfalfa for30years before the experiments was a little higher then that of the maize land which grew grain crops before.(3) General trends of soil temperature in two ridges and the furrow at the three times were as follows:8:00,5cm depth in ridges<5cm depth in furrows<10cm depth in ridges<10cm depth in furrows.14:00,10cm depth in furrows<10cm depth in ridges<5cm depth in furrows<5cm depth in furrows.20:00,5cm depth in furrows<5cm depth in ridges<10cm depth in furrows<10cm depth in ridges.(4) The results of flat maize farmland experiment showed:The trends of soil temperature effects were:plastic film mulch> straw return> nitrogen fertilization, full plastic film mulch> half plastic film mulch> no mulch,1500kgC/ha amount of straw return>750kgC/ha amount of traw return> no straw returning. The full plastic film mulch increased the soil temperature with no mulch by an average of2.3℃and half plastic film mulch increased by1.4℃. The warming effects of plastic film mulch lasted until tasseling stage (August), and plastic film mulch made no significant effects on soil temperature after tasseling stage. Straw return basically increased temperature at5cm depth in the early stage, and it had a bigger effect on temperature with no film mulch than with full plastic film mulch.(5) There were no significant effects on soil teperature when applying fertilizers in neither two ridges and the furrow nor in flat farmland. Both two ridges and the furrow and flat farmland showed that the soil temperature at deep layer was more stable than the shallow layer. The effects of air temperature on soil temperature at shallow layer were bigger than the deeper layer.(6) The soil temperature showed a significant linear correlation with the air temperature in both two ridges and the furrow and flat farmland. The bare two ridges and the furrow had the best linear correlation. In flat farmland the soil temperature without applying plastic film and straw showed the best linear correlation, which decreased when the degree of plastic film mulch and the amounts of straw return increased.