Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,New approaches for improving phosphorus acquisition and aluminum tolerance of plants in marginal soils,Cliff Johnston Purdue University,(,用,于改善边缘土壤中植物的磷摄取和铝耐受性的新,方法,),New approaches for improving p,1,+P+C+N,-P+C+N,Maintaining adequate soil fertility of P lives in the tension of providing adequate P to the plant while minimizing P losses to protect the environment.,(,保持足够的土壤磷肥力处于向植物提供足够的磷的,“,张力,”,，同时使磷损失最小化以保护环,境,),(,缺,磷,),(,富,磷,),+P+C+N-P+C+NMaintaining ade,2,(,可溶性磷肥,),(,植物磷,),(,稳定有機態磷,),(,不稳定,有機態磷,),(,微生物磷,),(,可溶性磷,),(,不稳定,無機態磷,),(,强吸附,無機態,磷,),(,磷岩石,),(,初级磷矿物,),(,次,级磷矿物,),(,無機態,),(,有機態,),(,快,),(,慢,),(,慢,),(可溶性磷肥)(植物磷)(稳定有機態磷)(不稳定(微生物磷),3,Phosphorus Cycle in Soils,Imports,Soil Processes,Fertilizers,Agricultural,By-products,Municipal and,Industrial,By-products,Sorbed P,Clays,Al,Fe Oxides,Secondary P Minerals,Ca,Fe,Al,Phosphates,Primary P Minerals,Apatites,Soil Solution P,(H,2,PO,4,-,HPO,4,-2,),Organic P,Soil Biomass(Living),Soil Organic Matter,Soluble Organic P,Leaching,and Drainage,P Removed with Crop,Surface Waters,(Eutrophication),Erosion/Runoff,Immobilization,Mineralization,Exports,Desorption,Sorption,Dissolution,Precipitation,Dissolution,Plant Residue,Plant,Uptake,Originally,soil phosphorus is derived by primary minerals,mainly rock phosphate in the form of apatite.These are relatively insoluble minerals.,Fe-O,Phosphate(PO,4,),As soils weather,the primary minerals containing P are lost and the remaining P is strongly bound to secondary minerals,included iron and aluminum oxides.,The pH of the soil determines nutrient availability.It is what we call a master variable.For soil phosphorus,optimal plant uptake occurs under near neutral pH conditions,All of these factors ultimately determine the availability of P to the plant and if the plant will be P deficient.,Phosphorus Cycle in SoilsImpor,4,Soil Phosphorus,(,土壤,磷,),Soils contain 500-2500 kg total P/ha,(,土壤總磷含量,500-2500,公斤,/,公頃,),About 75%of total P is in inorganic form in agricultural soils(25%in forest soils).,(,土壤總磷含量,500-2500,公斤,/,公頃,),Phosphorus in soil solution is nearly always 1 mg P L,-1,.,(,土壤溶液中的磷总是小於,1mg,P/L),We rely upon soil extractants to extract higher concentrations of P that can be correlated with soil testing procedures,these include Olsen,Bray P1 or Mehlich3,(,我们依靠土壤提取剂提取更高浓度的磷，可以与土壤测试程序相关，这些包括,Olsen,，,Bray P1,或,Mehlich3),The remaining P is tied up in organic matter and minerals that are relatively insoluble.,(,剩,余的磷被束缚在相对不溶的有机物质和矿物质,中,),Soil Phosphorus(土壤磷)Soils con,5,Method,(,方法,),Solution,(,溶液,),Soil type,(,土壤类型,),Conditions,(,条件,),Bray 1,0.003 M NH4F+,0.025,M HCl pH 3.75,Acid soils rich in iron,not,in neutral to calcareous soils,not in clayey soils with high degree of exchangeable bases,(,富含铁,的,酸性土壤，不,適用,中性,與,钙质土壤，也不,適用,在具有高度可交换碱的粘土土壤,),1:10(w:v),5 min shaking,Mehlich 3,0.015 M NH,4,F,+,0.2M CH,2,COOH+0.25 M NH,4,NO,3,+0.013 M HNO,3,+0.001 M EDTA,All soils,(,所有土壤,),1:10,(w:v),5 min shaking,Olsen,0.5 M NaHCO,3,pH 8.5,Calcareous soils,extended to all soils except highly acidic soils,(,除了高度酸性的土壤，钙质土壤扩展到所有土壤,),1:20(w:v),30 min shaking 20 deg C,Method(方法)Solution(溶液)Soil,6,Soil Factors and P Availability,(,土壤因子和磷,可用性,),Total amount of P present,(,磷总量,),Soil“age”(weathering status),(,土壤,“,年龄,”-,风,化状态）,pH:,Maximum availability near pH 6.5,(,磷最大可用性在,pH 6.5,),Mineralogy,(,矿物,類型,),Acid soils controlled by Al and Fe compounds,(,酸性,土壤中，铝和铁化合物控制磷的可利用性,),Alkaline(basic)soils controlled by Ca and Mg compounds,(,碱,性土壤中，鈣和鎂化合物控制磷的可利用性,),Soil Factors and P Availabilit,7,3 4 5 6 7 8 9,Soil pH,pH 6.5 for,optimum,availability,Insoluble Fe,Al,&,Mn phosphates,Adsorption to oxides,and clay,InsolubleCa and Mg,phosphates,Phosphate Fixation,Soil pH Effect on P Adsorption and,Precipitation,(,土壤,pH,影響磷的吸附和沉淀,),(pH 6.5,為磷最佳可用性,),形成,不,溶性铁，铝和锰磷酸,盐,或,吸附,到氧化物和粘土,不,溶,性,磷酸,钙和磷酸镁,(,磷固定,),3 4,8,H,3,PO,4,H,2,PO,4,-,HPO,4,-2,PO,4,-3,pK,1,=2.1,pK,2,=7.2,pK,3,=12.35,Dominant form of P present in highly weathered soils,Forms of phosphate in the soil,solution,(,磷酸盐在土壤溶液中的形態,),Plant-available forms:H,2,PO,4,-,HPO,4,2-,(,植物可利用的磷形態：,H,2,PO,4,-,HPO,4,2-,),P in solution must be constantly replenished from inorganic slowly-available P and organic P,(,溶液,中的磷必须从无机缓慢存在的磷和有机磷中不断补充,),H3PO4H2PO4-HPO4-2PO4-3pK1=2.1,9,15,30,40,Soil test P recommendations for corn and soybean,(,玉米和大豆的土壤磷建议测试,),153040Soil test P recommendati,10,Understanding the chemistry of phosphorus in highly weathered soils,(,了解高度风化土壤中磷的化学性质,),Understanding the chemistry of,11,Highly weathered soils have been degraded naturally over the past millions of years.,(,高度风化的土壤在过去几百万年中已经自然降,解,),These soils are characterized,by,(,这,些土壤的特点是,),:,Low fertility,(,低肥力,),Low pH,(,低,pH),Low P availability,(,低磷可用性,),High P sorption capacity(fixation),(,高度吸附磷的,能力,固定,),Toxic levels of aluminum,(,铝毒害,),Low P and toxic Al are principal constraints to crop production in highly weathered soils,(,低磷和铝毒害是高度风化土壤中作物生产的主要限制因素,),Highl