Effects Of Different Nutrient Management Measures On Soil Phosphorus Morphology And Availability

Soil is the supplier of plant nutrient resources,which restricts the productivity of terrestrial ecosystems.Phosphorus?P?is one of the main nutrient elements affecting plant growth,and it is also an important guarantee for plant growth,development and agricultural production.Soil is the main source of plant phosphorus,but not all the forms of phosphorus can be directly absorbed and utilized by plants.The effectiveness of soil phosphorus on plants depends mainly on their presence in the soil.Therefore,it is the key to clarify the existence of soil phosphorus in the migration,transformation and accumulation process and bioavailability in the environment.It can also provide a reliable scientific basis for rational fertilization in the agricultural production.In this study,three experiments were used as the framework,combined with soil physicochemical properties,soil total phosphorus,olsen phosphorus,inorganic phosphorus,organic phosphorus,nuclear magnetic resonance extracted soil phosphorus compounds as indicators,from the standpoint soil phosphorus activation form and effective Sexual perspective,comparing the relationship among the various indicators.The spatial variability of soil phosphorus in large-scale transects was investigated.The effects of different nutrient management on soil phosphorus form and availability were studied.The effects of different nutrient management on soil phosphorus form and availability under long-term experiment were studied.Designed to:1)Analysis of the relationship between phosphorus form in soil and other soil properties;2)systematically clarify the spatial variability of soil phosphorus forms and its driving factors;3)The content and morphology of phosphorus compounds were determined by comparative chemical continuous extraction method and ³¹P-NMR nuclear magnetic resonance measurement,revealing the dynamic changes of phosphorus in soil;4)From the perspectives of different nutrient management models,land use patterns,soil types,and crop yields,the factors affecting the shape,spatial distribution and effectiveness of soil phosphorus were systematically revealed.The main findings are as follows:1.Through the study of spatial variation of soil phosphorus form on large-scale sample belts,it was found that the concentrations of total phosphorus,available phosphorus,inorganic phosphorus,and organic phosphorus in the tested zonal soils ranged from 179.8 to 825.2,2.41 to15.3,92.6 to 351.2,and 14.7 to 474.4 mg·kg^-1,respectively.Available phosphorus,inorganic phosphorus,and organic phosphorus accounted for 1.17%–5.28%,42.5%–91.9%,and8.08%–57.5%,respectively,of the total phosphorus.The concentrations of four organic phosphorus components?i.e.,active,moderately active,moderately stable,and highly stable organic phosphorus?obtained through continuous chemical extraction were 1.38–30.9,8.63–213.7,3.01–32.2,and 1.73–199.2 mg·kg^-1,respectively,which accounted for6.18%–15.1%,31.8%–58.7%,2.29%–21.4%,and 11.8%–51.2%of the total organic phosphorus.According to solution ³¹P NMR spectra,Phosphonate was not detected in the tested soils,except in brown coniferous forest soil and dark brown soil,whereas deoxyribonucleic acid was not detected in lateritic red soil.In general,regardless of whether chemical extraction or solution ³¹P NMR spectroscopy,the concentrations of total phosphorus,available phosphorus,inorganic phosphorus and organic phosphorus and its fractions tended to decrease from brown coniferous forest soil in the cold temperate zone to latosol in the tropical zone.There was a correlation between phosphorus forms identified using continuous chemical extraction method and those identified using ³¹P NMR spectroscopy.Orthophosphate was most closely related to active organic phosphorus;phosphomonoester and phosphonate were most closely related to moderately active organic phosphorus;and pyrophosphate and phosphodiester were most closely related to moderately stable organic phosphorus.2.Through the study of soil phosphorus form and availability under different nutrient management models on the same soil;this study compared the effects of ISSM with improved practice?IP?,high-yield practice?HY?,and current farming practice?FP?on phosphorus forms in an Alluvic Primosol of Northeast China by using chemical and spectroscopic(³¹P NMR)analysis.The concentrations of total P and Olsen P were in the order FP<IP<HY<ISSM;the order for inorganic and organic P fractions obtained by chemical analysis was also the same except for Ca₁₀-P,which showed an opposite order.³¹P-NMR spectroscopy showed that inorganic orthophosphate,pyrophosphate,and orthophosphate monoesters were higher and orthophosphoric acid diesters in subsurface soil were less in ISSM than in HY,IP,and FP.3.The results of long-term localization experiments on black soil for 30 years according to different nutrient management models showed that the content of total phosphorus and available phosphorus in M₄NPK?M₄+NPK?treated with high amount of pig manure combined with chemical fertilizer was higher than other five species significantly.Treatment:?1?M₀CK?control,no fertilization?;?2?M₀NPK?nitrogen?N?,phosphorus?P?and potassium?K?fertilizer??3?M₂CK?pig manure 30 tons/hectare?;?4?M₂+NPK?5?M₄CK?pig manure 60 tons/hectare?.The order of soil total phosphorus?TP?,available phosphorus,inorganic phosphorus and organophosphorus components was usually M₀CK<M₀NPK<M₂CK<M₂NPK<M₄CK<M₄NPK.In the surface soil,the content of each component of the inorganic phosphorus treatment(Ca₂-P,Ca₈-P,Ca₁₀-P,Al-P,Fe-P and O-P)is 1.33 to 27.81,1.65 to 17.59,1.06 to 1.58,1.65 to 2.65,1.08 to 3.60,and 0.85 to 3.92 times of M₀CK,respectively.Among the components of organic phosphorus,the content of MLOP in M₄CK in subsurface soil was significantly higher than that in M₀CK,M₀NPK and M₂CK,but the difference between M₂NPK,M₄CK and M₄NPK treatment was not significant.