Effects Of Conservation Tillage On Soil Evapotranspiration In Spring Wheat Fields

Effect on the 7 years protective cultivating field experimenting which is located in Semi-arid area of Loess Plateau, and studied different conservation tillage of dryland farming farmland evapotranspiration and yield characteristics, The results show as following :(1 )The total crop evapotranspiration[0] have been increased by using No-tillage with straw mulch (NTS).The tendency of evapotranspiration in the spring wheat fields is approximately as:No-tillage with straw mulching(NTS)>Conventional tillage(T)>No-tillage(NT)> Conventional tillage with straw incorporation(TS). The water consumption in NTS is the largest as 9.18%,10.76%,14.06%, more than that in T, NT, TS. The water consumption in TS is the least, which is to say that the water consumption in NTS is much more than that in T, NT, TS as 27.76mm, 32.53mm, 42.51mm. In general, the variation of evapotranspiration will must go as a process of a gradual change, which is similar with a parabolic curve. The evapotranspiration in the spring wheat field reaches the peak in June, which takes up about 41.3% of the total evapotranspiration.(2)The evapotranspiration(E) of traditional cultivation surpasses protective cultivation in all circumstances. E in the spring wheat field under the circumstance of diverse cultivation measures appears as TS>T> NT>NTS, 141.72mm, 140.46mm, 125.19mm, 114.75mm. The ratio in E/ET are 53.8%,48.8%,37.2%,34.9%, which takes one step ahead that NTS can efficiently keep the water in the soil, and improve the yield performance and WUE.(3)The evaporation rate of inhibition for NTS is much more obvious. As the growing performance of the spring wheat in both the initial and the later stages is small in its leaf area index, low in its soil coverage,and too much and strong sunshine, which makes the E higher than the T. It appears NT>TS>NTS in April, NTS>TS>NT in May, and NTS>NT>TS in both May and July. It can be inferred that except that in April, NTS is obvious in its evaporation rate of inhibition, while NT and TS are instable.(4)The evapotranspiration appears a remarkable straight relevance with soil water. The evapotranspiration of spring wheat rises with the promotion of the soil temperature, as when the temperature is higher than 30℃, the evapotranspiration of spring wheat sharply rises almost as a straight line. The evapotranspiration of spring wheat has a negative relevance with atmospheric humidity, and it reduces when atmospheric humidity rises.(5)The evapotranspiration and T/E rise the same pace with its output and WUE and their influence on the output is mainly in June and July, during which the influence in June is much more obvious.