Effects Of Soil Surface Mulching And Fertilization On Soil Phosphorus Transformation And Availability In Dry Farmland

Soil phosphorus?P?is one of the most important nutrient elements to improve crop yield and maintain agroecosystem stability.The chemical forms and behaviors of phosphorus in the soil directly affect productivity and yields of crops.The contradiction between the continuous application of phosphate fertilizer and the inherent phosphorus reserves makes the improved efficiency of phosphorus utilization be one of the main scientific problems to ensure the sustainable development of agriculture and the sustainable utilization of phosphate rock resources through different agricultural technical measures to regulate soil phosphorus transformation.Therefore,based on years of mulching and fertilization field experiment,the soil samples were collected at different growth stages of spring maize in different soil layers?0-20 and 20-40 cm?,we detected the different forms of soil phosphorus content,analyzed the effects of different soil surface mulching and different fertilization on phosphorus content,morphological transformation and availability of spring maize at different growth stages and soil layers.The experiment we did can be used to explore the reasonable control measures to improve the availability of soil phosphorus in the region,to improve the season and sustainable utilization rate of phosphate fertilizer,to provide some scientific basis for the scientific management of phosphorus in dryland cropland of the Loess Plateau.?1?The contents of total P and Olsen-P in the soils of 0-20 cm soil layer were significantly higher than those in 20-40 cm soil layer at different stages.The addition of organic fertilizer could significantly increase soil total P and Olsen-P,and the influence of0-20 cm is more significant than that in 20-40 cm.The different surface mulching,NM,GM and FM,significantly affected the content of available phosphorus in 0-20 cm and 20-40 cm soil layers during the critical growth period of spring maize.?2?Ca₁₀-P contents in 0-20 cm and 20-40 cm soil layers were the highest in the contents of inorganic phosphorus in soils with different surface mulching and different fertilization.During the growth period,the content of Ca₈-P in 0-20 cm soil layer increased first and then decreased,and the content of Fe-P in 0-20 cm and 20-40 cm soil layer increased gradually.?3?The surface mulching could significantly affect the transformation of inorganic phosphorus in different soil layers of dryland farmland,and accelerated the increase of Ca₂-P content?first phosphorus source?in 0-20 cm soil layer by GM and FM,and reached peaks in V10 and R1.The second phosphorus source and potential phosphorus source content such as O-P,Al-P and Ca₈-P in 20-40 cm soil layer increased,and it can promote the uptake and utilization of phosphorus in soil.?4?Phosphorus combined with inorganic nitrogen fertilizer increased Ca₈-P?second available phosphorus source?to a certain extent,and reduce the relative content of Ca₂-P?first phosphorus source?.Addition of organic fertilizer could generally improve the effectiveness of potential phosphorus source in key growth periods of maize.Compared with P and NP treatments,MNP treatment increased the contents of Ca₂-P?first phosphorus source?and Ca8-P?Second effective phosphorus source?,reduced the insoluble phosphorus source?O-P?content at R1 stage.?5?The results showed that the alkaline phosphatase was mainly affected by the growth period,tended to decrease,increase and then decrease along with the growing season.The effects of different fertilization and mulchings were not significant.The correlation analysis showed that alkaline phosphatase activity was significantly correlated with O-P at P<0.001levels,and was significantly correlated with Olsen-P,Ca₈-P and Fe-P at P<0.01 levels,and the correlations with Ca₁₀-P,Al-P were not significant.?6?The results of path analysis showed that Ca₈-P had the greatest effect on the direct effect of phosphorus forms on alkaline phosphoric acid.The direct effects of Ca₂-P and Al-P were positive under the influence of indirect effects,indicating that the indirect effect can not be ignored.