Agroforestry buffers on nitrogen reduction in groundwater on a grazed hillslope

Agricultural practices often contribute to the transport of solutes into groundwater; thus, low-cost strategies that extract nutrients from groundwater are essential address water pollution. This study evaluated effects agroforestry (tree + grass; AB [cottonwood {Populus deltoides Bortr. ex Marsh.}]) and grass buffers (GB; [tall fescue Schedonorus phoenix (Scop.) Holub, Red clover {Trifolium pretense L.}, Lespedeza {Lespedeza Michx}]) on nitrogen (N) concentrations. The experiment consisted two grazing watersheds, one with an another a GB treatment. Buffers were not grazed since 2001. Three wells representing summit, backslope, foot-slope positions installed at each watershed. Water samples collected biweekly November 2019 January 2022 analyzed for total (TN) dissolved N (DN). Dissolved (DN) TN concentrations after in well 99% (5.36–0.06 mg L−1) 85% (9.04–1.37 lower than mean concentration summit backslope wells. Similarly, DN 94% (1.95–0.11 62% (2.86–1.07 L−1), during warm periods probably due plant uptake denitrification buffer zone. Results showed buffers, especially deep-rooted trees proximity table, decreased can be used as conservation practice