Hille Sandra, Graeber Daniel, Kronvang Brian, Rubæk Gitte H, Onnen Nils, Molina-Navarro Eugenio, Baattrup-Pedersen Annette, Heckrath Goswin J, Stutter Marc I
J Environ Qual. 2019 Mar;48(2):322-329. doi: 10.2134/jeq2018.01.0042.
Vegetated buffer strips (VBS) between agricultural areas and surface waters are important retention areas for eroded particulate P through which they may obtain critically high degrees of P saturation imposing high risk of soluble P leaching. We tested topsoil removal and three harvesting frequencies (once, twice, or four times per year) of natural buffer vegetation to reduce P leaching with the aim to offset erosional P accumulation and high degrees of P saturation. We used a simple numerical time-step model to estimate changes in VBS soil P levels with and without harvest. Harvesting offset erosional deposition as it resulted in an annual ammonium oxalate-extractable P reduction of 0.3 to 2.8% (25-cm topsoil content) in soils of the VBS and thus, with time, reduced potential P leaching below a baseline of 50 μg L. Topsoil removal only marginally reduced potential leaching at two sites and not anywhere near this baseline. The harvest frequency only marginally affected the annual P removal, making single annual harvests the most economical. We estimate 50 to 300 yr to reach the P leaching baseline, due to substantial amounts of P accumulated in the soils. Even in high-erosion-risk situations in our study, harvesting reduced soil P content and the P leaching risk. We suggest harvesting as a practical and efficient management to combat P leaching from agricultural VBS, not just for short-term reductions of dissolved P, but also for reductions of the total soil P pool and for possible multiple benefits for VBS.
农业区域与地表水之间的植被缓冲带（VBS）是侵蚀性颗粒态磷的重要截留区域，通过这些区域，磷可能会达到极高的饱和度，从而带来可溶性磷淋溶的高风险。我们测试了去除表土以及对天然缓冲植被进行三种收获频率（每年一次、两次或四次）对减少磷淋溶的影响，目的是抵消侵蚀性磷的积累以及高程度的磷饱和度。我们使用一个简单的数值时间步长模型来估计收获和不收获情况下VBS土壤磷水平的变化。收获抵消了侵蚀性沉积，因为它导致VBS土壤中草酸铵可提取磷每年减少0.3%至2.8%（25厘米表土含量），因此，随着时间的推移，将潜在的磷淋溶降低到50微克/升的基线以下。仅在两个地点，去除表土对潜在淋溶的降低作用微乎其微，远未达到这个基线水平。收获频率对每年的磷去除量影响甚微，使得每年单次收获最为经济。由于土壤中积累了大量的磷，我们估计需要50到300年才能达到磷淋溶基线。即使在我们研究中的高侵蚀风险情况下，收获也降低了土壤磷含量和磷淋溶风险。我们建议收获作为一种实用且高效的管理措施，以对抗农业VBS中的磷淋溶，不仅用于短期减少溶解态磷，还用于减少土壤总磷库，并为VBS带来可能的多重益处。
