• ISSN 1008-505X
  • CN 11-3996/S
DING Jia-hui, WANG Qi, FAN Bing-qian, ZHANG Shuai, CUI Jian-yu, HU Zhao-ping, CHEN Qing. Activation potential of soil legacy phosphorus by EDTA and citric acid evaluated with consecutive extraction method in the calcareous soil[J]. Journal of Plant Nutrition and Fertilizers, 2020, 26(2): 362-369. DOI: 10.11674/zwyf.19098
Citation: DING Jia-hui, WANG Qi, FAN Bing-qian, ZHANG Shuai, CUI Jian-yu, HU Zhao-ping, CHEN Qing. Activation potential of soil legacy phosphorus by EDTA and citric acid evaluated with consecutive extraction method in the calcareous soil[J]. Journal of Plant Nutrition and Fertilizers, 2020, 26(2): 362-369. DOI: 10.11674/zwyf.19098

Activation potential of soil legacy phosphorus by EDTA and citric acid evaluated with consecutive extraction method in the calcareous soil

  • Objectives Long-term phosphorus (P) application causes the occurrence of high residual but low available P in soil, in which soil acidification and leaching of Ca2+ and Mg2+ are prone to occur. We investigated the effect of using EDTA and citric acid to activate the P in calcareous soils, thereby providing a theoretical basis for reducing P fertilizer application and increasing P use efficiency.
    Methods All the calcareous soils were collected from Fangshan district, Beijing. The total P contents in low-P, high-P and dolomite amended (DA-soil) soils were 0.95, 1.90 and 1.91 g/kg, and available P contents were 7.39, 160 and 152 mg/kg, respectively. Indoor sequential extraction method was used to simulate the activation of P from soils, with EDTA and citric acid as extractants. In low-P soil, the concentrations of EDTA and citric acid were 0.05 g/L and extracting time was 12 h; in high-P soil and DA-soil, the concentrations were 0.5 g/L and extracting time were 12 h and 1 h. The extraction were repeated 10 times, with deionized water as control. The contents of P, Ca, Mg, Fe and Al in the extracts were measured, and the cumulative extracting amount of each element was calculated. Soil P fraction was conducted at the end of extraction.
    Results In low-P soil, both EDTA and citric acid were not significantly effective on the cumulatively extracted P which accounted for < 3% of the soil total P (TP). However, in high-P soil and DA-soil, both of EDTA and citric acid exhibited a strong P extracting capacity and the cumulatively extracted P accounted for more than 20% of the TP. Generally, the extracting amount of P in the high-P soil and DA-soil was 7−64 times higher than that in the low-P soil. And, citric acid extracted more P than EDTA (P < 0.05). The extracted P by deionized water, EDTA and citric acid were all significantly and positively correlated with the extracted Al and Fe in the low-P soil, significantly and positively correlated with Al, Fe, Ca and Mg in the high-P soil (r >0.78), but not significantly correlated with Al in the DA-soil. After 10 extractions by deionized water, EDTA and citric acid, the soil Ca2-P content was increased in low-P soil, compared to the pristine soil. The soil Ca2-P, Ca8-P contents on the other hand were significantly decreased by 16.1%, 14.9% and 37.1%, 5.4% in high-P soils extracted with the EDTA and citric acid, respectively, compared with those extracted with the deionized water. In addition, the soil Al-P content was significantly decreased by 31.4% with citric acid extraction. In the DA-soil, EDTA and citric acid showed similar extracting capacity on the change of the soil P content.
    Conclusions Both EDTA and citric acid may not possible to activate too much P from low-P soil, while may activate more than 20% of total P in the long run in the high-P soil, even though amended with dolomite. The activated P are mainly from Ca2-P and Ca8-P, and a small proportion from Al-P and Fe-P.
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