Phosphorus Adsorption Saturation of Ferrihydrate as an Index of Phosphorus Availability to Paddy Rice |
| |
Authors: | X H Shao C H Xing S T Du C Y Yu X Y Lin Y S Zhang |
| |
Institution: | 1. Ministry of Education Key Lab of Environmental Remediation and Ecosystem Health , College of Natural Resources and Environmental Science, Zhejiang University , Hangzhou, China;2. Ministry of Education Key Lab of Environmental Remediation and Ecosystem Health , College of Natural Resources and Environmental Science, Zhejiang University , Hangzhou, China;3. State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences , Nanjing, China |
| |
Abstract: | ABSTRACT The characteristics of phosphorus (P) sorption/desorption of artificially synthesized ferrihydrate and the relationship between P adsorption saturation of ferrihydrate, rice growth, and P uptake by rice (Oryza sativa L.) were studied. The results obtained from experiments showed that the artificially synthesized ferrihydrate had a very large adsorption potential to P, with 45045 μg P g?1 of maximum adsorption capacity (Qm). Phosphorus adsorption isotherm of ferrihydrate could be fitted very well with the Langmuir equation. Desorption of P adsorbed by ferrihydrate was controlled mainly by P adsorption saturation of ferrihydrate. Phosphorus adsorbed by ferrihydrate with saturation of less than 30% was hardly desorbed. Phosphorus desorption slowly increased with the increase of P saturation from 30% to 60%, but sharply increased with P saturation of greater than 60%. Thus it could be seen that P adsorption saturation should be a key factor affecting the availability of P adsorbed by iron oxides and be a better index than the quantity of oxalate-extractable P in estimating P phyto-availability in flooded soils. A Bioassay using rice indicated that 50% of P adsorption saturation could be used as a critical index for diagnosing status of P supplied by ferrihydrate-bonded P at the tillering stage of rice. |
| |
Keywords: | ferrihydrate P adsorption saturation P uptake rice |
|
|