长期施肥后简育湿润均腐土中磷素形态特征的研究

FORMS OF PHOSPHORUS IN HAPLI-UDIC ISOHUMOSOLS SOILS AFTER LONG-TERM FERTILIZATION

对黑土(简育湿润均腐土)长期定位施肥15年后土壤磷素形态进行分析研究。结果表明:土壤中积累的Al-P、Ca2-P量与施磷量成正相关;只施NK能促进植物对Ca8-P的吸收;闭蓄态磷(Oc-P)含量均较低。施磷肥能增加黑土Fe-P含量,却未能增加Ca10-P含量。黑土各形态无机磷的含量大小顺序为:Fe-P>Ca10-P>Al-P>Ca8-P>Ca2-P>Oc-P。施磷能增加土壤中有机磷(O-P)的含量,但不能增加土壤有机质含量。土壤有机质含量均有不同程度的下降。本试验黑土中施入N 112.5 kg hm-2a-1和P 20 kg hm-2a-1能保持土壤中无机磷(I-P)平衡。

Change in forms of phosphorus in a typical Hapli-Udic Isohumosols （black soil） under a 15-year long-term fertilization experiment was studied. Results show that accumulation of soil Al-P and Ca2-P was positively related to P application rate; application of NK stimulated the plant to absorb Cas-P; and the concentration of Occluded-P（Oc-P） was decreased. P application did increase the content of Fe-P in the black soil, but did not the content of Ca10-P. In terms of content in the black soil, the various forms of in-organic P were in the order of Fe-P〉 Ca10-P〉 Al-P〉 Cas-P〉 Ca2-P〉 O-P. P fertilizer application increased organic P in the soil, but it did not increase the content of organic matter. Instead, the content of organic matter dropped to a varying degree in different treatments. Application of N 112.5 kg hm^-2 a^-1 and P 20 kg hm^-2 a^-1 could keep I-P in balance in the soil.