Effects Of Different Modified Materials On Phosphorus Transformation And Availability In Saline Soil

Calcareous soil has a strong ability to fix phosphorus(P),so it is more difficult for plants to use P due to salt stress in saline soil.In practice,only increasing the amount of phosphate fertilizer can promote plants to absorb P,resulting in a low utilization rate of phosphate fertilizer.Adding different modified materials can improve soil properties or reduce the fixation of phosphate in the soil,which can also improve the phosphate fertilizer use efficiency and P nutrition of crops.In this study,210 days of indoor incubation,pot experiment and field experiment were designed.Taking salinized soil(irrigated desert soil)in hexi corridor of Gansu province as the research object.The effects of sulfur(S),biological fertilizer(B),organic fertilizer(M)and wheat straw(WS)on P availability and wheat P nutrition in salinized soil were studied when an equal amount of P(KH₂PO₄)was added.The purpose was to provide theoretical support for improving the efficient utilization of P resources in Hexi corridor area.The main results of this paper are as follows:1 Changes of P morphology and availability in salinized soil under different application of modified materials and phosphate fertilizersIncubation test showed that.,After 210 days of incubation,the content of Olsen P in soil treated with sulfur,biological fertilizer,organic fertilizer and wheat straw increased by 3.55%,3.74%,4.63%and 5.09%,respectively,compared with the control.At the end of incubation,Ca₂-P and Ca₈-P treated with biological fertilizer increased by 16%and 11%,Ca₈-P and Fe-P treated with straw increased by 7.4%and 13.72%,respectively,and O-P content decreased by 46.86%compared with the control.Meanwhile,the content of soil microbial biomass P treated with different modified materials was significantly higher than control,and increased with the increase of the proportion of addition.At 16 days,the soil microbial biomass P content reached the maximum value.Treatment with M_2.00,B_1.00,WS_4.00 and S_0.45increased by 34.66%,34.52%,28.19%and 23.89%,respectively.The relationship between P availability and P morphology was analyzed.When soil Olsen P was lower than 90 mg kg^-1,soil microbial biomass P increased with the increase of soil Olsen P.Soil Ca₂-P,Al-P,Ca₁₀-P and soil Olsen P content under single application of different modified materials showed significant positive correlation(P<0.05),while Ca₈-P,Fe-P,O-P and soil Olsen P content showed significant negative correlation(P<0.05).2 Effects of different modified materials on the bioavailability of PPot experiment results show that the uptake of P and the content of available P in the soil of wheat were significantly increased in both single application and combined application of different modified materials.Compared with the control,the content of available P in soil treated by S_0.15,B_0.50,M_1.00 and WS_2.00 increased by 3%,4%,7%and 8%,respectively.The P content of wheat treated by S_0.15,B_0.50,M_1.00 and WS_2.00 increased by 17%,18%,18%and19%,respectively.The P uptake of wheat treated by S_0.15,B_0.50,M_1.00 and WS_2.00 increased by28%,35%,40%and 33%,respectively.Comparatively speaking,single application is better than combination application.The wheat P uptake in combination with sulfur,bio-bacterial fertilizer,organic fertilizer and straw was the same as that of the straw treatment with high addition ratio.And there was a significant positive correlation between the wheat P uptake and the soil Olsen P as well as the relative biomass of wheat and the soil Olsen P.Organic fertilizer could promote the absorption of P nutrition of wheat in soil.3 Effects of different modified materials on wheat growth and P absorptionField experiments were carried out to compare the effects of the modified material on wheat yield and P absorption.It was concluded from the field experiment that in hexi corridor area,the P content,wheat P uptake and available P in soil could be improved by reducing phosphate fertilizer and applying different modified materials.And improving the utilization rate of phosphate fertilizer significantly.The panicle number,grain number and 1000-grain weight of wheat in salinized soil were increased,and the yield was significantly increased.The yield of wheat in the first year was shown as 80%conventional+organic fertilizer(high)>80%conventional+biological bacterial fertilizer(high)>organic fertilizer(high)?80%conventional+biological bacterial fertilizer(low)>80%conventional+organic fertilizer(medium)>80%conventional+organic fertilizer(low)>conventional?80%conventional.In the second year,wheat yield was shown as 80%conventional+organic fertilizer(high)>80%conventional+biological bacterial fertilizer(high)>organic fertilizer(high)?80%conventional+biological bacterial fertilizer(low)>80%conventional+organic fertilizer(medium)>80%conventional+sulfur(low)?80%conventional+organic fertilizer(low)>80%conventional?conventional.The yield of 80%conventional+organic fertilizer(high)wheat was the highest of all treatments.The results showed that the application of modified materials to partially replace inorganic fertilizers could significantly improve the efficiency of P nutrient utilization.In summary,the four materials of sulfur,bio-bacterial fertilizer,organic fertilizer and straw can increase the content of soil Olsen P and improve the effectiveness of P.And the effect of straw is generally better than sulfur,biofilm and organic fertilizer.P fertilizer was combined with sulfur,bio-bacterial fertilizer,organic fertilizer and straw are beneficial to the formation of Ca₂-P,Ca₈-P,Fe-P and Al-P and to the conversion of the undissolved P to active P compared to the control.And Ca₈-P was the main form of soil fixation of available P in hexi corridor.Compared with other materials,bio-bacterial fertilizer can promote the increase of soil microbial P and enhance the bioavailability of P.In the salinized soil,according to the characteristics of P nutrient absorption,yield and partial productivity of P fertilizer.Therefore,in the case of applying phosphate fertilizer,combined with the application of organic fertilizer or biological fertilizer is of great significance for efficient utilization of in saline soil.