Response Of Soil Olsen-p To P Balance In Typical Cropland Of China Under Long-term Fertilization

In this thesis,9 typical Cropland were selected from 9 long-term fertilization experiment sites in china.The evolutions of Olsen-P of 9 soils under different treatments were analyzed systematically and compared to summarize their spatial and temporal evolution characteristics and to explore the evolution process of soil Olsen-P under different fertilization,and to illuminate the relationship between soil Olsen-P and soil P supply.The main results and conclusions were as follow,which provided theoretical supports for efficient and sustainable use of phosphorus resources and the rational application of fertilizers.The results showed that long-term application of NP,PK,NPK and NPKM resulted in significant increased for the Olsen-P.While the soil Olsen-P content remained stable or showed a decreasing trend for the CK,N andNK treatment.NPKM treatment increased rate of Olsen-P were higher than other application of chemical fertilizer (NP, PK, NPK) sites.Long-term of the chemical fertilizer combined with manure to increased the amount of Olsen-P was the higher than chemical P fertilizer observably.The phosphorus balance showed little changes over the entire studying period across all the sites. There were significant differences in the averaged phosphorus balance among different treatments, with an order of CK,N,NK< PK,NP,NPK,NPKS < NPKM,NPKM+. For the NPK treatment that was applied to all the sites, the averaged phosphorus balance (26 kg/hm~2/yr -149 kg/hm~2/yr) showed a significantly positive relationship (p < 0.01) with phosphorus application rate.With an average surplus of 100 kg/hm~2 phosphorus,the average soil Olsen-P can increase of 4.04 mg/kg,4.01 mg/kg and 3.31 mg/kg ,for the NP,PK and NPK treatments,respectively.The order was NP>PK>NPK.The average soil Olsen-P can increase of 10.70 mg/kg, 6.19 mg/kg and 4.67 mg/kg,for the NPKM,NPKS and 1.5NPKM treatments,respectively,and the order was NPKM>NPKS>1.5NPKM.The results shoe that an average surplus of 100 kg/hm~2 phosphorus,the chemical fertilizer combined with manure increased Olsen-P was higher than chemical fertilizers.