Habibiandehkordi Reza, Lobb David A, Owens Philip N, Flaten Don N
J Environ Qual. 2019 Mar;48(2):314-321. doi: 10.2134/jeq2018.04.0129.
The continued phosphorus (P) impairment of freshwaters and the associated risk of eutrophication raise questions regarding the efficiency of current beneficial management practices (BMPs) for improving water quality. Vegetated buffer strips (VBSs) are widely encouraged BMPs for reducing P export from agricultural land. However, there is a lack of evidence regarding the long-term efficiency of VBSs for reducing legacy P losses. This research used soil analyses to investigate the P removal efficiency of an unmanaged VBS for controlling P loss from agricultural land in Manitoba, Canada, between 1954 and 2011. The results showed statistically significant retention of total P, Olsen extractable P, and 0.01 M CaCl extractable P by a 5-m wide VBS compared with field soils. We found that surface soils at 5-m into the VBS had a significantly greater P sorption capacity and a smaller degree of P saturation (DPS) than adjacent field soils. The elevated DPS in field soils is likely associated with gradual P enrichment as a result of manure or fertilizer application over time and the strong affinity of P compounds for soil. Although P stratification in the VBS over 57 yr resulted in a significant increase (∼11%) in DPS of VBS topsoil compared with VBS subsoil, our findings do not support the saturation of VBS soils with P. However, cutting and removal of vegetation from VBS could be a useful strategy to remove P from VBS and minimize possible P remobilization associated with vegetation senescence, especially where the climate is cold and runoff is dominated by snowmelt.
淡水持续受到磷（P）污染以及随之而来的富营养化风险，引发了关于当前改善水质的有益管理措施（BMPs）效率的问题。植被缓冲带（VBSs）是广泛提倡的减少农业用地磷输出的BMPs。然而，缺乏关于VBSs减少遗留磷损失长期效率的证据。本研究利用土壤分析调查了1954年至2011年期间加拿大曼尼托巴省一条未管理的VBS控制农业用地磷流失的磷去除效率。结果表明，与田间土壤相比，5米宽的VBS对总磷、Olsen可提取磷和0.01M CaCl可提取磷具有统计学上显著的截留作用。我们发现，VBS内5米处的表层土壤比相邻田间土壤具有显著更高的磷吸附能力和更低的磷饱和度（DPS）。田间土壤中DPS升高可能与随着时间推移施用粪肥或肥料导致的磷逐渐富集以及磷化合物对土壤的强烈亲和力有关。尽管57年来VBS中的磷分层导致VBS表土的DPS比VBS底土显著增加（约11%），但我们的研究结果并不支持VBS土壤被磷饱和。然而，砍伐和清除VBS中的植被可能是从VBS中去除磷并最大限度减少与植被衰老相关的磷再迁移的有效策略，特别是在气候寒冷且径流以融雪为主的地区。
