有机酸根阴离子对土壤无机磷生物有效性的影响

EFFECTS OF ORGANIC ANIONS ON THE BIOLOGICAL AVAILABILITY OF INORGANIC PHOSPHORUS FROM DIFFERENT FRACTIONS IN SOILS

在黑麦草生长期间,施用柠檬酸钠、草酸钠、酒石酸钠、苹果酸钠等4种有机酸盐,研究不同有机酸根阴离子对黄棕壤和水稻土中不同形态无机磷的活化作用。结果表明:草酸根阴离子活化黄棕壤中总无机磷能力最强,酒石酸根阴离子活化水稻土中总无机磷能力最强。黄棕壤被草酸根阴离子活化的无机磷主要是Ca P和Al P,而水稻土被酒石酸根阴离子活化的无机磷则是Fe P和O P。4种有机酸根阴离子活化黄棕壤中总无机磷能力的大小顺序为草酸根>柠檬酸根>苹果酸根>酒石酸根,活化水稻土总无机磷能力的大小顺序为酒石酸根>柠檬酸根≈草酸根>苹果酸根。同一土壤中同一组分无机磷,不同有机酸对其活化能力不一;不同土壤中同一组分无机磷,同种有机酸对其活化能力也有较大差异。有机酸的施入虽可增加植物的总吸磷量,但增加量并非仅来自于无机磷的释放,很可能是土壤有机磷释放的增加。在大多数情况下施入有机酸钠促进了总无机磷的释放,但各无机磷组分间的消长情况不一。

By adding citrate, oxalate, tartrate and malate into soils during the growth period of rye grass, the effects of different organic ligands on the release of phosphorus (P) from different inorganic P (Pi) fractions in the yellow brown soil and the paddy soil were studied. The results showed that oxalate was the most effective in promoting the release of total Pi in the yellow brown soil, while the tartrate in the paddy soil. The dominant Pi released from the yellow brown soil was Ca\|P and Al\|P. In the paddy soil, it came from Fe\|P and O\|P mobilized by tartrate. Phosphorus\|mobilizing capability of organic acids revealed in the yellow brown soil followed this order: oxalate>citrate>malate>tartrate. In the paddy soil, this order was as below: tartrate>citrate≈oxalate>malate. The results demonstrated that organic ligands were different in their capabilities of mobilizing Pi and the same organic anion appeared also a discrepancy in mobilizing P in different soils. Although the addition of organic ligands into soils could increase the amount of P absorbed by rye grass, the more uptake of P, however, was not only due to the more release of Pi, also partly from organic P. In many cases, organic ligands promoted the release of the total Pi, while among different fractions, some increased and others decreased.