A long-term （21-year） field experiment was performed to study the responses of soil inorganic P fractions and P availability to annual fertilizer P application in a calcareous soil on the Loess Plateau of China. Soi...A long-term （21-year） field experiment was performed to study the responses of soil inorganic P fractions and P availability to annual fertilizer P application in a calcareous soil on the Loess Plateau of China. Soil Olsen-P contents increased by 3.7, 5.2, 11.2 and 20.6 mg P kg-1 after 21-year annual fertilizer P application at 20, 39, 59, and 79 kg P ha-1, respectively. Long-term fertilizer P addition also increased soil total P and inorganic P （Pi） contents significantly. The contents of inorganic P fractions were in the order of Ca10-P 〉 Cas-P 〉 Fe-P 〉 A1-P 〉 occluded P 〉 Ca2-P in the soil receiving annual fertilizer P application. Fertilizer P application increased Cas-P, A1-P and Ca2-P contents as well as their percentages relative to Pi. Pi application increased Fe-P and occluded P contents but nor their percentages. Soil Ca10- P content remained unchanged after fertilizer P application while its percentage relative to Pi declined with increasing fertilizer P rate. All Pi fractions but Ca10-P were correlated with Olsen-P significantly. 90% of variations in Olsen-P could be explained by Pi fractions, and the direct contribution of Cas-P was predominant. Long-term annual superphosphate application would facilitate the accumulation of soil Cas-P, and thus improve soil P availability.展开更多
基金Supported by the National Basic Research Program (973 Program) of China (No.2005CB121102)the Knowledge Innovation Program of the Chinese Academy of Sciences (No.kzcx2-yw-424)the National Natural Science Foundation of China (No.30500077)
文摘A long-term （21-year） field experiment was performed to study the responses of soil inorganic P fractions and P availability to annual fertilizer P application in a calcareous soil on the Loess Plateau of China. Soil Olsen-P contents increased by 3.7, 5.2, 11.2 and 20.6 mg P kg-1 after 21-year annual fertilizer P application at 20, 39, 59, and 79 kg P ha-1, respectively. Long-term fertilizer P addition also increased soil total P and inorganic P （Pi） contents significantly. The contents of inorganic P fractions were in the order of Ca10-P 〉 Cas-P 〉 Fe-P 〉 A1-P 〉 occluded P 〉 Ca2-P in the soil receiving annual fertilizer P application. Fertilizer P application increased Cas-P, A1-P and Ca2-P contents as well as their percentages relative to Pi. Pi application increased Fe-P and occluded P contents but nor their percentages. Soil Ca10- P content remained unchanged after fertilizer P application while its percentage relative to Pi declined with increasing fertilizer P rate. All Pi fractions but Ca10-P were correlated with Olsen-P significantly. 90% of variations in Olsen-P could be explained by Pi fractions, and the direct contribution of Cas-P was predominant. Long-term annual superphosphate application would facilitate the accumulation of soil Cas-P, and thus improve soil P availability.
