低分子量有机酸对石灰性土壤有机磷组成及有效性的影响

为探索提高土壤磷素有效性的途径,采用室内培养的方法,研究不同有机酸对土壤速效磷含量及有机磷组分的影响。结果表明,添加有机酸后土壤速效磷含量发生显著变化,其中草酸处理下土壤速效磷含量显著高于其他处理,而柠檬酸和苹果酸对土壤速效磷含量具有抑制作用,其活化量为负值;随着培养时间的延长,速效磷含量缓慢降低。速效磷含量随着草酸浓度的升高而升高,随着苹果酸、柠檬酸浓度的升高而降低;有机酸处理后,土壤活性、中活性、中稳性有机磷升高,高稳性有机磷降低,这说明有机酸能促进土壤有机磷由有效性低的形态逐步向有效性高的形态转化,其中草酸的作用效果总体上较柠檬酸和苹果酸强。

Effect of Low Molecular Weigh Organic Acid on Organic Phosphorus Fraction and Availability in Calcareous Soil

To explore the effective way to improve soil phosphorus availability,indoor incubation experiments were conducted.So,the effect of low molecular weight(LMW) organic acids on organic phosphorus fraction and its availability in calcareous soil was investigated.The results showed that the LMW organic acids could significantly stimulate the soil available phosphorus.For calcareous soil,the ability of oxalic acid in mobilizing soil available phosphorus was higher than that of malic or citric acid;citric and malic acid could significantly restrained soil available phosphorus activity in calcareous soil.The content of soil available phosphorus decreased with the lengthened of the incubation time.Moreover,with the increase of oxalic acid concentration,or the decrease of citric and malic acid concentrations,the content of soil available phosphorus increased.After disposed by LMW organic acids,the contents of liable organic phosphorus(L-OP),moderate liable organic phosphorus(ML-OP),and moderate stable organic phosphorus(MS-OP) increased,while the content of high stable organic phosphorus(HS-OP) decreased in calcareous soil.As a conclusion,LMW organic acids can improve the soil phosphorus availability by affecting the organic phosphorus fractions.