Excessive phosphorus (P) in runoff contributes to eutrophication of fresh water bodies. Studies have shown that manure and effluent applied from animal feeding operations to waste application fields (WAFs) have contributed to excess P in segments of the North Bosque River in east central Texas. There is a growing need for environmentally sound, economically viable, and easy to establish best management practices to control such pollution. Vegetative buffer strips offer a potential solution for reducing runoff P from WAFs by extracting it from soil and by reducing sediment P delivery (due to reduced runoff and soil erosion) to streams. In a field study, ten plots (5m x 5m) were assigned to five replicated treatments, namely control (bare, without having any plant cover), cool season grass, warm season forb, warm season grass, and warm season legume to assess their efficacy of runoff sediment control and P sequestration potential from soil. These plots were established on a coastal Bermuda grass WAF that received dairy lagoon effluent. A runoff collection system, a 1m x 1m sub-plot with a runoff conveyance and collection apparatus, was installed on the upstream and downstream margins of each plot. Natural rainfall runoff samples were collected and analyzed subsequently for total P, soluble P, and total suspended solids in the laboratory. Additionally, the total mass of runoff collected from each sub-plot was calculated. Results suggested that the warm season forb and warm season grass were the most effective vegetative covers for the reduction of runoff P, followed by coastal Bermuda and cool season grass, respectively. The lesser amount of runoff total P in these two treatments was due to lesser runoff mass and lesser sediments in the runoff due to initial interception of rain and less raindrop impact on soil because of denser vegetative cover in both treatments compared to all other treatments.

The Upper North Bosque River (UNBR) watershed is under a Total Maximum Daily Load (TMDL) mandate to reduce Phosphorus (P) due to excess nutrients in the watershed. To address these problems, Texas A&M University researchers have developed a turfgrass sod Best Management Practice (BMP) to remove excess nutrients from impaired watersheds. Turfgrass harvest of manure fertilized sod removes a thin layer of topsoil with most of the manure applied P. Plot and field scale research has demonstrated the effectiveness of turfgrass to remove manure phosphorus (P). In order to assess the impact of the turfgrass BMP on a watershed scale, the Soil and Water Assessment Tool (SWAT) was used to predict water quality in the UNBR watershed. The SWAT model was modified to incorporate turfgrass harvest routines to predict manure and soil P export through turfgrass sod and soil during harvest. SWAT simulations of the BMP predicted stream load reductions of 20 to 36% for P loads in the UNBR depending on the implementation scenario, an average reduction of 31% for total N and 16.7% for sediment for all the scenarios, at the watershed outlet. The SWAT model also predicted up to 176 kg/ha P removed per sod harvest when fertilized with 100 kg manure P/ha, and 258 kg/ha of P removed per sod harvest when the manure P application rate was 200 kg/ha. In addition, depending on the implementation scenario, the turfgrass BMP could export between 262 and 784 metric tons of P out of the UNBR watershed every year. Manure fertilized turfgrass has the advantage of slow releasing nutrients from the composted dairy manure, so it would not require any additional P for life. This means reduced urban non-point source pollution and lower maintenance cost compared to regular sod. These modeling simulations complement the wealth of research that shows the effectiveness of the turfgrass BMP.