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Purpose of the study is to improve the high total phosphorus but low available phosphorus alkaline soil of the Loess Plateau of China by lowering the soil pH sulfur fertilizer application and pH decreased) which can release the available phosphorus in the soil, and Increase the crop yield.April 2009 to July, pot experiment was carried out to study the effect of different patterns of sulfur fertilizer application and pH decreased on grain yield of Spring wheat in Semi-arid Loess Plateau China. The study includes nine treatments:(1) CK; (2) K2SO4-1 (0.30 g/kg, K2SO4/soil); (3) K2SO4-2 (0.87 g/kg, K2SO4/soil); (4) S1 (0.06 g/kg, S/soil); (5) S2 (0.16 g/kg, S/soil); (6) S3 (0.54 g/kg, S/soil); (7) H2SO4-1(pH decreased 0.35 units); (8) H2SO4-2(pH decreased 0.44 units); (9) HCl(pH decreased 0.55 units).From April 2010 to October 2010, through the planting, the influence to the coin production and water use efficiency of administrating S and administrating S and attapulgite. The study includes 7 treatments:(1) CK; (2) S1 (S 22.5 kg/ha without attapulgite); (3) S2 (S 66.0 kg/ha without attapulgite); (4) S3 (S 225 kg/ha without attapulgite); (5) ST1 (S1 22.5 kg/ha with 20 % attapulgite); (6) ST2 (S2 66.0 kg/ha with 20% attapulgite); (7) ST3 (S3 225 kg/ha with 20 % attapulgite)。Attapulgite accounted for the total weight of fertilizer (basal+sulfur+attapulgite) of 20%.The results of pot experiments are as follows:1. In water treatment, except for H2SO4-2, K2SO4, the sulfur and acid administration both produce higher production and water use efficiency than CK. Under drought conditions, except for H2SO4-2, K2SO4 and S1, the sulfur and acid administration both produce higher production and water use efficiency than CK. H2SO4-2 production and water use efficiency was significantly lower than CK. The production and water use efficiency have no significant difference with CK. Meanwhile, the spring wheat shoots mass, effective spike number per pot and the root-shoot ratio(R/T) of K2SO4, sulfur and acid treatment group was higher than CK.2. The base of the soil pH value in the experiment is 8.43. Before sowing, the acid treatment reduced the PH value of H2SO4-1, HCl, H2SO4-2 to 8.08,7.88,7.99, respectively, which increased to 8.22,8.12,8.16. The PH value of K2SO4 treatment did not change after harvest, while that of K2SO4-2 treatment decreased by 0.1 units, the pH values of S1, S2, S3 treated soil decreased by 0.12,0.07,0.2 units under sufficient water supply conditions, and by 0.17,0.14,0.28 units under drought conditions.3. The H2SO4-1, H2SO4-2, HCl in available phosphorus, organic carbon and C/N were higher than CK after acid treatment.4. Both application of soil sulfur and decreased soil pH values promote the release of soil available phosphorus and C/N increase. After harvesting, sufficient water supply, except for H2SO4-1, the available phosphorus content of others are higher than the control; the SOC of S3 and H2SO4-1, HCl treatment significantly increased; H2SO4-1, HCl treatment has a higher C/N value. Under drought stress conditions, the organic phosphorus content of each group is also higher than the control, but only HCl treatment is significantly different; the organic carbon content of each treatment group is not significantly different from the control; H2SO4-1, HCl has a higher C/N value.5. Except for H2SO4-2, all the processing, both in adequate water supply or drought stress, the available phosphorus, organic carbon and C/N have increased of soil after harvesting, compared to before planting. The results of field experiment are as follows:1. Compared to CK, S1 has a higher production and water use efficiency; however, S2, S3 produced no significant difference in yield, but with a large decrease in water use efficiency.2. Compared to the control, yield and water use efficiency of ST1, ST2 treatment have increased significantly.3. Relative to the S1, S2, the yield and water use efficiency of ST1, ST2have increased significantly.Application of K2SO4, sulfur and reducing soil pH can promote the release of AP in the alkaline soil and the C/N increase, effective spring wheat spikes and increased biomass and the yield of spring wheat.In the experimental conditions, moderate amount of sulfur can be applied to enhance the yield of corn, while improving the water use efficiency. However, the amount of sulfur must be controlled in a certain range, excessive application will cause cut in yield and water use efficiency will reduction. In this experiment, the optimum amount of sulfur is S1 (2.249 g/m2,22.5 kg/ha). Attapulgite and sulfur mixed fertilizer, compared to the application of sulfur alone, improve the yield of maize and water use efficiency.
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