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| Effects of chelating agents on phosphorus release from different phosphorus sources |
| Received:December 05, 2017 |
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| KeyWord:chelating agents;different phosphorus sources;molybdate unreactive phosphorus;molar ratio |
| Author Name | Affiliation | E-mail | | LIU Shi-lei | College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China | | | WANG Qi | College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China | | | FAN Bing-qian | College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China | | | ZHANG Qiang | Kingenta Ecological Engineering Group Co., Ltd., Linyi 276700, China
National Key Laboratory of Nutrient Integrated Management, Linyi 276700, China | | | CHEN Qing | College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China
National Key Laboratory of Nutrient Integrated Management, Linyi 276700, China | qchen@cau.edu.cn |
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| Abstract: |
| To study the effects of fertilizer synergists, such as chelating agents, on the release effect of different phosphorus sources, can provide a comprehensive understanding of the form of the released phosphorus in liquid phase by the chelating agent.Two different types of soils (acid red soil and calcareous soil) and five kinds of mineral phosphate (calcium hydrogen phosphate (DCP), octacalcium phosphate (OCP), hydroxyapatite (FA), aluminum phosphate (Al-P), iron phosphate (Fe-P)) as phosphorus sources were selected. Then, the effect of the chelating agent (EDTA-2Na) on the phosphorus release rate and release form from different phosphorus sources were studied through a laboratory chemical extraction test. The results showed that:(1) Chelating agents could promote the release of phosphorus from different phosphorus sources, and the phosphorus release rate increased significantly with the increase of chelating agent concentration. (2) With the increase of chelating agent concentration, the ratio of molybdate unreactive phosphorus (MUP) to total phosphorus (TP) in the extracts decreased significantly in acid red soil and calcareous soil, whereas it significantly increased in three kinds of Ca-P compounds and did not change significantly in Al-P and Fe-P compound treatments. (3) Only a small amount of phosphorus in the extracts existed in the form of free phosphate.Under the EDTA-2Na treatment of 3.00 g·L-1, the ratio of free phosphate to total phosphorus in the extracts of DCP, Al-P, and Fe-P was only 0.43%, 1.12%, and 0.63%, respectively. (4) The molar ratio of TP to the corresponding metal ions in the solution was almost unchanged after the release of phosphorus from different phosphorus sources. |
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