Multispecies Riparian Buffers Trap Sediment and Nutrients during Rainfall Simulations

Abstract

AbstractA study was conducted to evaluate the ability of a multispecies riparian buffer (MRB) to remove sediment, nitrogen, and phosphorus from cropland runoff. Simulated rainfall was applied to 4.1‐ by 22.1‐m bare cropland source areas paired with either no buffer, a 7.1‐m‐wide switchgrass (Panicum virgatum L. cv. Cave‐n‐Rock) buffer, or a 16.3‐m‐wide switchgrass‐woody plant buffer. Each treatment plot combination had three replicates. The switchgrass buffer trapped 70% of the incoming sediment, while the switchgrass‐woody buffer trapped more than 92%. In general, these buffers retained 93% of sand and silt particles and 52% of clay particles. During a 2‐h rainfall simulation at 25 mm h−1, the switchgrass buffer removed 64, 61, 72, and 44% of the incoming total N, NO3−N, total P, and PO4‐P, respectively. The switchgrass‐woody buffer removed 80, 92, 93, and 85% of the incoming total N, NO3−N, total P, and PO4‐P, respectively. During a 1‐h rainfall simulation at 69 mm h−1, the switchgrass buffer removed 50, 41, 46, and 28% of the incoming total N, NO3−N, total P, and PO4‐P, respectively. The switchgrass‐woody plant buffer removed 73, 68, 81, and 35% of the incoming total N, NO3−N, total P, and PO4‐P, respectively. The switchgrass buffer was effective in trapping coarse sediment and sediment‐bound nutrients. But the additional buffer width with high infiltration capacity provided by the deep‐rooted woody plant zone was effective in trapping the clay and soluble nutrients.