低分子量有机酸对土壤磷的活化作用

Mobilization of Soil Phosphorus by Low-molecular-weight Organic Acids

模拟缺磷胁迫下植物根系分泌的有机酸种类和数量。用化学浸提法研究了柠檬酸、酒石酸、苹果酸和草酸对石灰性土壤和红壤磷的活化。结果表明,有机酸能明显促进石灰性土壤和红壤中磷的释放。柠檬酸和草酸对石灰性土壤磷的活化较强,苹果酸和酒石酸的活化作用较弱;柠檬酸和草酸对红壤磷的活化较强,酒石酸的作用次之,而苹果酸的活化作用较弱。经比较发现,有机酸对红壤磷的活化作用要大于对石灰性土壤磷的活化。在红壤上,有机酸对磷的活化与土壤中 Fe 和 Al 释放有显著正相关关系。质子对有机酸活化土壤磷起着十分重要的重要。在低 pH 时,柠檬酸所活化的磷大约有38%是质子的作用;32%左右是柠檬酸阴离子的贡献,质子和柠檬酸阴离子的交互作用占30%。

Extraction experiments were conducted to investigate the effect of low-molecular- weight organic acids on phosphorus release from 3 soils:2 calcareous soils and 1 acidic soil(red earth).It was indicated that the mobilization of soil phosphorus was significantly stimulated by organic acids for all of 3 soils tested.For calcareous soils,the ability of citric and oxalic acids in mobilizing soil phosphorus were higher than that of malic and tartaric acid.As for red earth, the mobilizing ability of organic acids for phosphorus followed the order:citric>oxalic>tartar- ic>malic acid.The phosphorus mobilized from red earth was higher than that from calcareous soils.The releases of soil phosphorus from red earth were highly correlated with soil aluminum and iron extracted.pH played a very important role in mobilizing soil phosphorus.At low pH, the 38% of phosphorus mobilized by citric acid was attributed by proton.The 32% of phos- phorus mobilized by citric acid was caused by citric anion.The interaction of proton and citric anion in mobilizing soil phosphorus was 30%.