The Synergistic Yield-increasing Effects Of Soil Carbon Andwater On Long-term Dryland Farming Spring Maize

Water plays a decisive role for dryland agriculture production, and has an important impact on soil organic carbon. To improve rainfed spring maize yield and water use efficiency, exploring the relations between soil carbon&water and production synergies,we research the effects of different nutrient managements on soil organic carbon and water, and the influences of soil carbon and water on corn yield and water use, to provide technical support and theoretical basis for dry farming, based on the22-yearexperimentof shanxi ShouYang rainfed farmland. The results are summarized as follows:1. Adding manure or straw is beneficial to improve soil organic carbon and utilization of water. By 2014, compared with no manure(no straw), the content of SOC in using manure(straw) treatment was increased by 14.6%(18.1%). Fertilizer, straw, manure with treatment can improve the top layer of soil moisture 1.4% ~ 8.2%, increase the pondage of 40-140 cm soil 6.1 ~ 19.5 mm. In most years manure treatment for water consumption is lower than no manure, the largest gap can be 29.7 mm. Affected by the nutrient inputs, water use efficiency of them increased by 25.0% ~ 114.5%.2. SOC is affected by soil moisture and can affect crop water consumption and water use efficiency. Organic carbon(C) and soil water content(W) of 0-20 cm layer are in accordance with equation C =-4.133W2 + 127.4W- 966.4, and for soil pondage(Po) are in accordance with equation C =-0.004Po2 + 3.206Po- 600.6, and both of the tow achieve significant correlation. Crop water consumption(Wc) and organic carbon content is quadratic equation Wc =-13.58C2 + 411.2C- 2705. The relationship between water use efficiency and organic carbon is linear.3.Reasonable ratio of fertilizer can increase the maize yield effectively. Hundred grain weight and yield of corn in no fertilizer treatment are the lowest, act as 24.38 g and 3.0t/ha respectively. Treatment 1(F105 S3000, M6000), 9(F105 S6000, M1500) and 11(F105 S3000, M3000) show the best result, hundred grain weight are increased by 28.7%, 27.1%, 27.1% than no fertilizer treatment, the average production of maize are more than 6.7 t/ha.4. Maize yield(Y) is affected by many factors, such as 0-20 cm soil water content(W), organic carbon content(C), soil pondage(Po) and water consumption(H) and there are significant correlations between them. Corn yield has a linear relation with the organic carbon, and a quadratic equation with the other three factors. When many factors were simulated, soil water content and organic carbon inputs(Ct) is the most close related with yield, fitting equation for Y=- 640.885- 21.1314 Ct + 87.8982W- 0.7677 Ct2+ 1.6146 Ct ·W- 2.9935W2(R2=0.9919),when the organic carbon inputs was 2.36 t/ha, 0-20 cm soil water content was 15.32%, production has a maximum value of 7.4 t/ha.In conclusion, reasonable nutrient managements and organic carbon inputs can improve soil carbon and water situation, increasing crop yield and water use efficiency.