W.K. Kellogg Biological Station, Michigan State University, Hickory Corners, MI, 49060, USA.
Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI, 48824, USA.
Sci Rep. 2021 Oct 13;11(1):20367. doi: 10.1038/s41598-021-99877-7.
Excessive phosphorus (P) applications to croplands can contribute to eutrophication of surface waters through surface runoff and subsurface (leaching) losses. We analyzed leaching losses of total dissolved P (TDP) from no-till corn, hybrid poplar (Populus nigra X P. maximowiczii), switchgrass (Panicum virgatum), miscanthus (Miscanthus giganteus), native grasses, and restored prairie, all planted in 2008 on former cropland in Michigan, USA. All crops except corn (13 kg P ha year) were grown without P fertilization. Biomass was harvested at the end of each growing season except for poplar. Soil water at 1.2 m depth was sampled weekly to biweekly for TDP determination during March-November 2009-2016 using tension lysimeters. Soil test P (0-25 cm depth) was measured every autumn. Soil water TDP concentrations were usually below levels where eutrophication of surface waters is frequently observed (> 0.02 mg L) but often higher than in deep groundwater or nearby streams and lakes. Rates of P leaching, estimated from measured concentrations and modeled drainage, did not differ statistically among cropping systems across years; 7-year cropping system means ranged from 0.035 to 0.072 kg P ha year with large interannual variation. Leached P was positively related to STP, which decreased over the 7 years in all systems. These results indicate that both P-fertilized and unfertilized cropping systems may leach legacy P from past cropland management.
过量的磷（P）施用于农田，会通过地表径流和地下（淋溶）损失导致地表水富营养化。我们分析了免耕玉米、杂交杨树（黑杨×毛白杨）、柳枝稷（蒲苇）、芒草（巨芒草）、本地草和恢复草地从 2008 年种植于美国密歇根州前农田中的总溶解磷（TDP）淋失损失，所有作物除玉米（13kg P ha 年）外均未施磷肥。除杨树外，所有作物在每个生长季末都收获了生物量。2009 年至 2016 年 3 月至 11 月期间，每周至每两周使用张力渗透计从 1.2m 深处采集土壤水，以测定 TDP，并用张力渗透计测定土壤水 TDP 浓度。每年秋季测量土壤测试 P（0-25cm 深度）。土壤水 TDP 浓度通常低于地表水富营养化经常观察到的水平（>0.02mg L），但通常高于深层地下水或附近溪流和湖泊中的水平。根据实测浓度和模拟排水估算的磷淋失率在不同作物系统间无统计学差异；7 年作物系统平均值范围为 0.035 至 0.072kg P ha 年，年际变化较大。淋失的 P 与 STP 呈正相关，在所有系统中 STP 都在 7 年内下降。这些结果表明，施磷肥和未施磷肥的种植系统都可能从过去的农田管理中淋失残留 P。
