The Diffrence And Mechanism Of The Relation Between Soil Olsen-P And P Budget Of Fluvo-aquic Soil Under Long-term Fertilization

The content of soil Olsen-P was different under long-term fertilization for the influence of P fertilizers,P budget,soil properties,et al.Soil Olsen-P was mainly affected by soil P budget,soil Olsen-P was positively linear related to P budget.The decrease of amout in P fertilizers could lead to the change of soil Olsen-P efficiency.Understanding the reason of soil Olsen-P efficiency changing with P fertilizers,could provide a theoretical basis for rational application of P fertilizer.In this paper,the response of soil Olsen-P to P budget was studied in Fluvo-aquic soil of Zhengzhou in Hehan Province under 5 treatments（CK,NK,NPK,NPKS and NPKM）.The diffrence in soil Olsen-P efficiency was anylized from P adsorption and desorption,P morphology,and soil properties,and so on.The main results as follows:（1）Soil Olsen-P was extremely significant（P<0.01）positive linear related to P budget in Fluvo-aquic soil of Zhengzhou.With 100 kg ha^-1 P deficit,soil Olsen-P decreased by 0.1-0.4 mg kg^-1;with 100 kg ha^-1 P surplus,soil Olsen-P increased by NPKM(5.5 mg kg^-1)>NPK(4.8 mg kg^-1)>NPKS(3.5 mg kg^-1).Compared with the application of chemical P fertilizers,the combination of organic fertilizer could significantly improve soil Olsen-P efficiency.Soil Olsen-P efficiency was mainly affected by Mehlich-Al³⁺,which could explain 69.5%of variance in soil Olsen-P efficiency.（2）There was a good fitness between the P adsorption curve and Langmuir equation（0.95<R²<1）.The application of P fertilizers could improve DPS of soil,and decrease Qm,K,MBC of soil significantly.The difference in soil adsorption parameter between NPK and NPKS was not obvious.Under NPKM,the value of Qm,K,MBC was obviously lower than other treatments,and the value of DPS,RDP,DPR was much higher than other treatments significanly.MBC,DPR,K,RDP could explain70.1%,15.9%,10.9%,1.8%（P<0.01）of the variance in soil Olsen-P efficiency.Soil colloid specific surface area was the main factors influcing P adsorption and desorption,which could explain 77.3%（P<0.01）of the variance in P adsorption and desorption.Organic matter affects the adsorption and desorption of phosphorus through the relationship between colloid specific surface area and pH,thus affecting soil Olsen-P efficiency.（3）Under treatments without P fertilizers,different P fractions decreased over time,and the content of Resin-P,NaHCO₃-Pi,NaOH-Pi,NaOH-Po decreased significantly with experimental year.After 28-year-long fertilization,the content of Conc.HCl.Pi and Conc.HCl.Po decreased significantly.So,non labile P fraction could be used after long time fertization.（4）The content of different P fractions was not obvious under NPK and NPKS,all P fractions under NPKM was higher than those under NPK and NPKS.After the application of P fertilizers,the content of Resin-P,NaHCO₃-Pi,NaHCO₃-Po increased significantly with experimental year.Under NPKM with higher soil Olsen-P efficiency,the lablie P fractions（Resin-P,NaHCO₃-P）and moderate labile P fractions（NaOH-P,Dil.HCl-P）were significantly high than those under NPK and NPKS.（5）NaOH-Pi was the main factors influcing soi Olsen-P efficiency,which could expalin 63.2%of the variance in soil Olsen-P efficiency.Under NPK and NPKS,the content of NaOH-Pi increased,then decreased over years,which was the same with the tendency of soil Olsen-P.Therefor,moderate labile NaOH-Pi was thought to be tha main P source of crop when P fertilizers decreased.（4）Under NPKM with high soil Olsen-P efficiency（SOE）,the content of the labile P（Ca₂-P,Resin-P,NaHCO₃-P）was relatively high,and would increase with experimental year.and its content would increase then decrease with time.The change of moderate inorganic labile P was similar with the change soil Olsen-P.Therefore,the moderate inorganic labile P pool was considerated to be the important P source for crop after 13-year long fertilization in Zhengzhou.In summary,compared with chemical phosphorus fertilizer,long-term application of chemical fertilizer combined with manure could improve the efficiency of soil cumulative phosphorus conversion to available phosphorus,which was soil Olsen-P efficiency（SOE）.The diffrence in soil P adsorption and desorption characteristics,the soil P morphology,soil properties were not obvious under NPK and NPKS.Using ³¹P-NMR and XANES techniques to further explore the true forms of soil phosphorus,combined with Hedley method and Jiang-Gu,the proportion of moderate inorganic labile P（Con.HCl-Pi,Ca₈-P,Orthophosphate,TCP）was largest under different P fertilization treatmentsin Zhengzhou,which were the main P fraction.Under treatment without P fertilizers,different P fractions decreased over time,soil Olsen-P efficiency was low.Under NPK and NPKS,before 2003,the amout of P fertilizers was high,labile P input was high,so soil Olsen-P efficiency was high;afer 2003,the amout of P fertilizers was decreased,moderate labile NaOH-Pi could be trasformed into labile P,soil Olsen-P kept at a high level,so soil Olsen-P efficiency decreased.The reason for high SOE under NPKM was that,the application of manure could improve the RDP,DPR of P,and the content of labile and moderate labile inorganic P...