摘要
摘要:明确土壤磷的活化潜力及释放特征是土壤遗留磷资源化利用的前提，以长期定位施肥的灰漠土为试验材料，选取不施肥（CK）、施氮磷钾化肥（NPK）、氮磷钾化肥与有机肥配施（NPKM）3种处理，以高浓度（10 mmol·L^-1）和低浓度（2 mmol·L^-1）柠檬酸对土壤遗留磷进行多次浸提，探究柠檬酸对长期不同施肥处理灰漠土遗留磷的活化潜力及特征。研究发现：不同施肥处理土壤遗留磷的活化总量为NPK > NPKM > CK，与土壤总磷含量变化一致；高、低浓度柠檬酸对供试灰漠土遗留磷的活化潜力基本相当（>80%）。供试土壤遗留磷的急剧释放伴随土壤pH的大幅下降，说明酸溶解是主要活化机制。高浓度柠檬酸活化整个阶段，NPK处理土壤磷的释放量均高于NPKM处理；而在低浓度柠檬酸处理前期，NPKM释放的磷量大于NPK，相关元素中仅与镁元素的释放一致，可见低浓度柠檬酸活化前期NPKM处理土壤磷的活化很可能来自镁磷。高浓度柠檬酸对灰漠土遗留磷的活化前期以无机Ca₈-P活化为主，后期以无机Ca₁₀-P活化为主。综上，柠檬酸可显著促进不同施肥处理灰漠土遗留磷的活化，鉴于灰漠土遗留磷的高活化潜力，可通过适当减量施肥及土壤磷高效利用管理等措施促进作物再利用。
关键词:柠檬酸/
遗留磷/
活化潜力/
施肥方式/
灰漠土
Abstract:Understanding soil phosphorus (P) characteristics and release potential is important for using the accumulated soil P (legacy-P). A long-term fertilization experiment in grey desert soil was performed to investigate the release potential and characteristics of soil legacy-P after mobilization with a low molecular-weight organic acid (i.e., citric acid). Grey desert soil was untreated (CK), treated with commercial fertilization (NPK) or organic manure plus commercial fertilization combination (NPKM), and extracted with citric acid at high (10 mmol·L^-1) or low (2 mmol·L^-1) concentrations. The results showed that the legacy-P release potential differed among the variable fertilization treatments and was consistent with soil total P concentrations (NPK > NPKM > CK). The legacy-P release potentials after citric acid extraction were similar at high and low concentrations and made up more than 80% of the soil total P. Rapid soil P release was accompanied by a sharp decrease in soil pH, indicating that acid dissolution is the primary release mobilization mechanism. Under NPK treatment, the mobilized P was greater than that under NPKM from the beginning to the end of mobilization. NPKM released more P at the beginning of mobilization with low citric acid concentration, similar to soil magnesium. These results suggest that magnesium-associated P played a major role in P mobilization under NPKM treatment. The high citric acid concentration primarily mobilized the inorganic Ca₈-P pool, followed by the inorganic Ca₁₀-P pool. Citric acid significantly facilitated P mobilization in fertilized grey desert soil. The high release potential indicates that grey desert soil legacy-P can be accessed by reducing fertilization and efficient P management practices.
Key words:Citric acid/
Legacy phosphorus/
Mobilization potential/
Fertilization pattern/
Grey desert soils



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