Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/1996
Publication Date: N/A
Interpretive Summary: Small plot studies are often criticized as not being relevant to what really happens in the field. One example is research conducted on the amount of buffer strip needed to reduce non-point source nutrient runoff. In this research, the amount of area that is fertilized is usually much smaller than the downslope plots which act as the buffer areas. The objective of this study was to determine the combined influences of pollutant source area and vegetative buffer strip length on removal of nutrients from runoff water from plots which were simulating pastures. The results indicated that the area treated with manure did not affect the nutrient concentrations reaching the buffer plots, however, the mass of nutrients increased because the volume of water increased as the area treated with manure increased. Effectiveness of the buffer strips varied with type of nutrient and ranged from 6.5 to 96.3% removal.
Technical Abstract: Vegetative filter strips (VFS) can reduce runoff losses of nutrients, solids, and other materials from land areas treated with fertilizers. While VFS effectiveness is known to be affected by lengths of pollutant source and VFS areas, there is little experimental evidence available to quantify this dependence. This is particularly true when the pollutant sources are pasture areas treated with animal manure. This study assessed the combined influences of pollutant source area (fesuce pasture treated with poultry litter) and VFS lengths on removal of total Kjeldahl nitrogen (TKN), ammonia nitrogen (NH3-N), nitrate nitrogen (NO3-N), ortho-phosppphorus (PO4-P), total phosphorus (TP), total organic carbon (TOC), total suspended solids (TSS), and fecal coliform (FC), from incoming runoff. Litter-treated lengths of 6.1, 12.2, and 18.3 m with corresponding VFS lengths of up to 18.3 m, 12.2 m, and 6.1 m, respectively, were examined. Runoff was produced dfrom simulated rainfall applied at 50 mm/h for 1 h of runoff. Analysis parameter concentrations were found to be unaffected by litter-treated length but demonstrated a first-order decline with increasing VFS length except in cases of TSS and FC. Mass transport of TKN, NH3-N, PO4-P, and TP increased with increasing litter-treated length (due to increased runoff) and decreased (approximately first-order) with increasing VFS length. Effectiveness of the VFS in terms of TKN, NH3-N, PO4-P, and TP removal from runoff ranged from 6.5 to 96.3% depending on the particular analysis parameter, litter-treated length, and VFS length. The data collected from this experiment can be helpful in developing and testing models that simulate VFS performance and thus aid in the design of VFS installed downslope of pasture areas treated with animal manure.