The Effects Of Manure Application Strategies On Crop And Soil Phosphorus Legacy

Organic fertilizer is an important fertilizer resource in modern agriculture.Animal derived organic fertilizer with livestock manure as raw material has the characteristics of large quantity,high nutrient content and concentrated resources.Rational use of this kind of organic fertilizer can improve crop yield and soil fertility.The traditional application of organic fertilizer generally determines the fertilization amount based on the nitrogen demand of crops(i.e.nitrogen based fertilization method).However,the content of nitrogen and phosphorus of livestock manure organic fertilizer is usually high,and the demand of crops for phosphorus is much lower than that of nitrogen.The method of determining the fertilization amount based on nitrogen is easy to lead to the accumulation of phosphorus in soil.If the amount of organic fertilizer is determined according to the needs of crops for phosphorus(i.e.phosphorus based fertilization method),it may lead to insufficient nitrogen or potassium for crop growth.The purpose of this study is to explore the reasonable application scheme of livestock manure organic fertilizer,not only consider the crop demand,but also avoid excessive surplus of phosphorus nutrients in the soil,so as to prevent soil nutrient leaching and adjacent water environment eutrophication.Therefore,a 10-year long-term positioning test of applying organic fertilizer based on crop nitrogen/phosphorus(nitrogen/phosphorus)demand and a 2-year short-term positioning test of Gefu agricultural cooperative in Gelan Town,Changshou animal husbandry Park(adjacent to Changshou Lake and the Yangtze River)were carried out at woodslee experimental farm on the Bank of Lake Erie,Ontario,Canada.Routine analysis and 31P nuclear magnetic resonance(³¹P-NMR)were used.The differences and characteristics of nitrogen/phosphorus based organic fertilizer fertilization schemes were discussed from the aspects of crop agronomic effects,soil phosphorus concentration,the existing forms of soil surplus phosphorus and its impact on soil microecology,in order to provide theoretical guidance for the scientific application of livestock manure organic fertilizer.The main results are as follows:1.Under the rotation of Maize(Zea mays L.)and soybean(Glycine max L.)in the typical clayey black soil of Lake Erie basin,the results of 10-year field positioning experiment showed that the yield of Maize Treated with phosphorus based liquid pig manure was significantly higher than that treated with phosphorus based and nitrogen-based solid pig manure(p?0.05).Nitrogen based solid pig manure treatment applied a large amount of nutrients,the yield of maize was only similar to the control,and the phosphorus surplus in soil was significantly higher than that in phosphorus based liquid and solid pig manure treatment(p?0.05),which posed a potential threat to the eutrophication of surrounding water bodies.Soil available phosphorus(Olsen-P)was mainly concentrated in the topsoil(30cm).The mass of available phosphorus in the topsoil treated with nitrogen-based liquid and solid pig manure reached 45.3 and 173.7kg ha^-1,respectively,which were 1.75 and 6.4 times higher than that before the experiment;The soil available phosphorus quality of nitrogen-based solid pig manure treatment was significantly higher than that of other treatments(p?0.05).The available phosphorus mass of topsoil soil treated with phosphorus based liquid pig manure was31.6 kg ha^-1,which was close to that treated with chemical fertilizer(30.1 kg ha^-1).The phosphorus surplus of topsoil soil in nitrogen-based solid swine manure treatment was significantly higher than that in other treatments(p?0.05).The agronomic efficiency(AGE_P),phosphorus utilization efficiency(including equilibrium method and apparent method)and phosphorus source availability coefficient(PSAC)of maize showed that the P-based manure scheme was significantly better than the N-based manure scheme(p?0.05),and the phosphorus utilization efficiency was high.Phosphorus source availability coefficient integrates organic phosphorus source,soil properties and crop bioavailable phosphorus to evaluate the impact of long-term manure application on phosphorus availability,which is more practical and comprehensive in evaluating the long-term sustainability of fertilization measures in agriculture and environment.The environmental risk of phosphorus fertilizer effect of liquid swine manure is slightly lower than that of solid swine manure.Soil phosphorus accumulation caused by nitrogen-based swine manure application scheme may become a potential threat to the ecological environment.Phosphorus based liquid or solid swinemanurefertilization management shows good agronomic and environmental benefits.2.³¹P-NMR technology was used to analyze 3 kinds of inorganic phosphorus and14 kinds of organic phosphorus compounds in 0-7.5(surface)and 7.5-15 cm(sub surface)soil of no fertilizer treatment,no phosphorus in chemical fertilizer,phosphorus content in chemical fertilizer and 3 kinds of organic fertilizer treatment based on crop phosphorus demand(i.e.liquid swine manure,solid swine manure and swine manure compost treatment)The contents of phosphorus compounds such as mononucleotide,phosphate monoester group 1,phosphate monoester group 3 and other phosphate diesters decreased significantly,while most of the phosphorus compounds in the soil without phosphorus fertilizer were greater in the surface layer than in the subsurface layer;The spectrum of phosphorus compounds in the soil surface and subsurface of each phosphorus containing treatment was similar,especially between phosphorus based organic fertilizer treatments.The total inositol hexaphosphate content of solid pig manure treatment in topsoil was significantly higher than that of other treatments,and the total inositol hexaphosphate content of organic fertilizer treatment in subsurface soil was significantly higher than that of chemical fertilizer treatment and no fertilizer control treatment.The content of total inositol hexaphosphate in the subsurface increased by 34.3%compared with that in the surface.The application of liquid pig manure was conducive to the movement of total inositol hexaphosphate to the lower soil.After 10 years,the phosphate monoester and phosphate diester of no fertilizer control treatment migrated to the lower soil,while the phosphate monoester of liquid pig manure,solid pig manure and pig manure composting and phosphate diester of solid pig manure treatment accumulated in the lower soil.There was a significant positive correlation between cM:D(Correction of phosphate monoester:phosphate diester)and available phosphorus in topsoil(p?0.05);There was a significant positive correlation between cM:D value of surface and subsurface soil and phosphorus concentration in soybean grain(2013)(p?0.05).The cycle of soil organic phosphorus directly or indirectly affects the absorption of phosphorus by crops.The mineralization of organic phosphorus forms has a significant impact on soil fertility and phosphorus surplus in agricultural soil environment.The results show that ³¹P-NMR technology can connect soil phosphorus cycle with sustainable agricultural management,and cM:D value may have important application value for agricultural production and agricultural soil environmental protection.3.The application test results of swine manure organic fertilizer of two crops(corn and potato)on abandoned farmland in Changshou District national modern animal husbandry Park of Chongqing showed that the yield of corn season was different from that of long-term test,that is,the yield of nitrogen-based fertilization treatment of four manure was significantly higher than that of phosphorus-based treatment(p?0.05),and even significantly higher than that of phosphorus-containing treatment of chemical fertilizer(p?0.05).The phosphorus source availability coefficient(PSAC)and the phosphorus fertilizer utilization efficiency of equilibrium method are not suitable for short-term experiments.Similar to the long-term positioning test,the agronomic efficiency(AGE_P)of P-based fertilization in maize season was 21.9?22.5,while the AGE_P value of nitrogen based fertilization was 4.1?8.7,only 1/3-1/5 of the former;The AGE_P value of potato quaternary phosphorus treatment was still significantly higher than that of nitrogen treatment(p?0.05).In terms of apparent phosphorus efficiency(APE_P),the APE_P values of nitrogen-based manure treatment in maize and potato seasons were significantly lower than those of phosphorus-based manure treatment(p?0.05);The APE_P value of phosphorus based solid pig manure was higher than that of other treatments in corn and potato seasons.After the harvest of two crops,there was a more obvious tendency of phosphorus surplus in nitrogen-based soil than in phosphorus-based soil,and the content of soil available phosphorus was similar to the results of long-term test.In the short-term experiment of two crops,after manure and chemical fertilizer were applied for 42 days,the release rate of soil available phosphorus in retting treatment was greater than that of crops,and the available phosphorus in nitrogen-based pig manure retting and nitrogen-based cow manure retting began to accumulate in the soil.The release rate of phosphorus in phosphorus based liquid pig manure was higher than that in phosphorus based solid pig manure and swine manure composting;The release of bound phosphorus in fresh solid pig manure was slow.After 58 days of fertilization,a large amount of phosphorus in fresh solid pig manure was released.After 92 days of fertilization,except for nitrogen-based pig manure composting,the available phosphorus in other nitrogen-based treatments continued to accumulate and reached the peak;In contrast to the nitrogen-based treatment,the soil available phosphorus of phosphorus-based manure treatment decreased or did not change compared with 58 days.After phosphorus was absorbed by crops in P based manure treatment,the content of available phosphorus in soil was relatively stable.In the whole crop growing season,the soil effective variation range of phosphorus based solid pig manure and P based pig manure composting is small,ranging from 33.9?37.9 mg kg^-1 and 36.9?38.4 mg kg^-1 respectively.The fertilizer effect of phosphorus fertilizer is sustained and stable,and the agricultural production and ecological benefits are better than other treatments.It may be a feasible utilization mode of swine manure organic fertilizer in Changshou animal husbandry Park,which is conducive to effectively reducing the use of chemical fertilizer consume swine manure in the park.4.The short-term test results of fresh solid pig manure and pig manure composting treatment of two crops showed that the agronomic efficiency of solid swine manure treatment was similar to that of swine manure composting treatment in corn season,and significantly higher than that of swine manure composting treatment in potato season;The apparent phosphorus efficiency of solid swine manure treatment was higher than that of phosphorus based swine manure composting treatment in corn season and potato season.The results showed that in potato cultivation,fresh solid swine manure from farm pigsty could be applied to the field without traditional composting treatment,and its fertilizer effect was significantly better than that of swine manure composting.After42,58,92 and 142 days,the inorganic phosphorus content of NaOH-EDTA extract accounted for 56%-93%of the total P in NaOH-EDTA extract,while the organic phosphorus(including inorganic polyphosphate)accounted for only 7%?44%.Compared with the long-term positioning test,it shows that the transformation of inorganic phosphates to inorganic polyphosphate and organic phosphates in soil is greater than that in short-term test.The cM:D value of each treatment is between 1.2and 4.9.Different from long-term manure treatment,cm:D value had no significant correlation with soil available phosphorus,corn grain phosphorus and potato tuber phosphorus concentration at four sampling times.The soil cM:D value of nitrogen-based solid swine manure and nitrogen-based swine manure composting treatment increased 58 days after fertilization,and the mineralization degree of soil organic phosphorus was strengthened 42 days after fertilization;After 92 days of fertilization,the soil phosphate monoester and cM:D of nitrogen-based solid swine manure and pig manure composting treatment showed a downward trend,indicating that the organic phosphorus cycle of manure treatment was affected by the growth cycle of maize;From92 days to 142 days after fertilization,the cM:D of the other five pig manure treatments increased from planting to stem and leaf growth,except that the cM:D of nitrogen-based pig manure retting treatment decreased slightly.These results suggest that crop growth may be the driving factor of soil organic phosphorus cycle,and crop growth promotes the transformation of organic phosphorus to inorganic phosphorus in soil.The dynamic changes of soil inorganic phosphorus and organic phosphorus compounds 42,58,92and 142 days after fertilization showed that the content of total inositol hexaphosphate changed greatly in these four periods.The dynamic changes of total inositol hexaphosphate content may be related to the growth period of corn and potato.Compared with nitrogen-based treatment,except for phosphorus-based solid treatment,phosphorus-based liquid and phosphorus-based retting release organic phosphorus compounds more smoothly during the sampling period,especially groups 1,2 and 3 of phosphate monoesters and phosphate diesters,that is,the fertilizer effect of phosphorus-based fertilization scheme is slow but stable.This phenomenon explains the internal reason why the yield of liquid pig manure in short-term test potato season is higher than that in nitrogen-based treatment,and can also reflect the advantages of liquid pig manure in long-term test from a molecular point of view.The results showed that in the process of short-term fertilization and crop growth,the di phosphate was continuously mineralized,and the mineralization process was related to the crop growth period.5.The microecological study of seven soil treatments in Changshou animal husbandry Park showed that in the four growth stages of corn potato rotation,nitrogen-based or phosphorus-based manure treatment could significantly increase the content of soil microbial biomass carbon(SMB-C)(p?0.05)compared with chemical fertilizer treatment,and the effect of nitrogen-based manure treatment on improving SMB-C was better than that of phosphorus-based treatment;The content of SMB-C and the number of bacteria,actinomycetes and fungi in soil decreased from September to October and increased from October to November.The content of soil microbial biomass carbon and the number of soil microorganisms were affected by the crop growth cycle.The bacteria and actinomycetes in soil treated with nitrogen-based manure were more active than those treated with phosphorus-based manure,and the effect of phosphorus-based manure on increasing the number of fungi was more significant.The number of microorganisms in soil is the most,followed by bacteria,fungi and actinomycetes.The soil alkaline phosphatase activity of N-based and P-based manure treatment was significantly higher than that of no fertilizer treatment and chemical fertilizer treatment(p?0.05).