Effects Of Different Straw Mulching Modes On Winter Wheat Yield And Soil Environment In Weibei Dry Plateau

The experiment, with different period and ammount of straw mulching on winter wheat planting in Shaanxi Heyang from 2007 to 2010, through determination about 0~200cm soil moisture, soil physical and chemical properties, physiological characteristics and yield of crops and crop water productivity such as indicators, and study different straw mulching modes on winter wheat and the soil environment in Weibei dryland, in order to improve the system of straw mulching cultivation techniques in dry land, and improve crop yields in dry farming areas, then provide a theoretical basis for improving the ecological environment of dry land. The main conclusions are as follows:1. Compared with bare land for planting of winter wheat seedling and heading stages, Straw mulch reduced 0~25cm soil temperature. The same coverage period, the rate of temperature decreases with the increase in the amount of coverage, in the same amount of coverage, the soil temperature of full coverage is higher than the growth period covered, but the difference was not significant.2. Straw mulching reduced soil bulk density of 0~60cm soil layer, in the same amount of coverage, the soil bulk density was less different between the full coverage and Wheat growth stages coverage mode. The soil bulk density increased in full coverage period with increasing of mulching quality, and the soil bulk density in 20~40cm is maximum. Overall, the middle coverage is better to improve the soil structure.3. In the three treatments, Aggregate content of full coverage larger than 0.25mm diameter increased by from 1.85 to 5.01% than the growth stage, under the same mulching way, different mulching amount, the aggregate content of greater than 0.25mm mechanical stability was increased with the increase in the amount of coverage, Compared with the experimental control, Coverage pattern reduces the aggregate index of instability in varying degrees, improve the stability of soil structure, the coverage was no significant difference among treatments.4. Compared with CK, 0~200cm soil moisture content with full coverage treatment was increased greater than growth coverage, and the soil moisture content in different soil layers were increased by 5.39~15.68%, and 3.01~8.30% in growth coverage during the growth season of winter wheat from 2007 to 2010. In 0~80cm soil layer, the soil water storage of 3 mulch amount in the full coverage is increased by 17.43mm~30.87mm than growth period, in 80~200cm, soil water storage with high amount of straw mulching in full coverage increased by 33.65mm than growth coverage. There are less increase in middle coverage and low coverage.In 0~80cm soil layer, the soil water storage of 3 mulch ammount in fallow period increased by 2.84mm～18.06mm than growth coverage; In 80～200cm soil layer, increased by 5.83mm～17.34mm. In growth period, soil water storage in full coverage increased by 27.66~52.79% than growth coverage in 0~200cm soil layer, and in fallow period, the water storage increased by 9.06～22.03%. The same mulch amount and different mulch period, soil water moisture showed full coverage>growth coverage. The same mulch period and different mulch amount, soil water moisture showed high coverage>middle coverage>low coverage>CK.5. Straw mulch can improve organic matter and available nutrient content of 0~60cm soil, in the same coverage period, the highest content of organic matter in the middle coverage. Available phosphorus content increased with increasing of mulching amount in full coverage, in growth coverage, the highest Available phosphorus content in the middle coverage.In the same coverage period, the highest Available K and Available N content in the middle coverage,and the full coverage improved the rate of Available K and Available N greater than growth coverage.6. Increase in coverage compared with CK, the highest stomatal conductance in middle coverage. In the full coverage, the intercellular CO2 concentration Ci of winter wheat increased with the increase of the amount of coverage. In the full coverage, the highest transpiration rate Tr in the middle coverage and in the growth coverage, the lowest Tr in the middle coverage . In the same coverage period, photosynthetic rate with high and middle amount coverage in the full coverage higher than growth coverage, and high coverage higher middle coverage.7. 3 years average grain yield of winter wheat shows that each coverage mode has a yield increase in Weibei Plateau. Compared with CK, the yield in full coverage increased by 21.38~27.93% and yield in growth coverage increased by 11.94~15.85%(P<0.05). The rate of increasing yield in the full coverage is larger than growth coverage, the largest yield increase with high and middle coverage. In full coverage, WUE shows a decreased trend with the increased amount of straw. In growth coverage, WUE of middle mulch is better than others. In the same amount of coverage, WUE in different periods showed that full coverage>growth coverage.8. Integrated 3-year fixed-point test results, full coverage with the middle amount can improve soil moisture, nutrients, yield and water use efficiency, and it is can be implemented in Weibei plateau.