The effect of soil organic matter on long-term availability of phosphorus in soil: Evaluation in a biological P mining experiment
土壤有机质对土壤中磷长期有效性的影响：生物磷开采实验的评价
- 关键词：
- 来源：
- ScienceDirect
- 类型：
- 学术文献
- 语种：
- 英语
- 原文发布日期：
- 2022-06-03
- 摘要：
- The plant uptake of legacy phosphorus (P) from over-fertilised agricultural soils could offer a solution to decrease dependency on finite mineral P resources. This study evaluated the long-term availability of legacy P in soils with an accelerated biological mining assay, thereby testing to what extent this availability is affected by soil organic carbon (SOC). A 15-month-long pot trial was set-up, in which 25 soils with 1.2–24% SOC were mined for P by continuous cropping and harvesting of ryegrass (Lolium perenne) in a plant growth cabinet. The cumulative uptake of P was, on average, 19% of the P associated with poorly crystalline iron (Fe) and aluminium (Al) (oxy)hydroxides (oxalate-extractable P; Pox). On average, half of this P could be taken up at rates fast enough to maintain crop production at > 90% of its potential. This P taken up before a 10% reduction in yield occurred, termed the critical cumulative P uptake (CCP), strikingly matched with the isotopically exchangeable P or “E value” of a soil (median CCP/E24h = 0.81), whereas it was markedly underestimated by Olsen P (median CCP/POlsen = 1.51). The fractions of plant-available Pox increased at increasing ratios of either P or SOC to the sum of Feox and Alox, suggesting that enhanced SOC contents reduce ageing of P by preventing its diffusion into micropores. That effect of SOC on P availability was more pronounced in soils with a low initial P saturation status. The comparison of the results from biological mining with available soil P pools determined in a (sterile) P desorption experiment could not confirm a significant contribution of organic P to plant P supply. Based on the set of soils in our study, our findings suggest that legacy P in well-fertilised agricultural soils could act as a sufficient P source for plants for several years to decades, and that this long-term availability is positively affected by SOC as long as the soil is not saturated with P.
- 所属专题：
- 135
