Phosphorus Runoff from Turfgrass as Affected by Phosphorus Fertilization and Clipping Management

Abstract

Phosphorus enrichment of surface water is a concern in many urban watersheds. A 3-yr study on a silt loam soil with 5% slope and high soil test P (27 mg kg(-1) Bray P1) was conducted to evaluate P fertilization and clipping management effects on P runoff from turfgrass (Poa pratensis L.) under frozen and nonfrozen conditions. Four fertilizer treatments were compared: (i) no fertilizer, (ii) nitrogen (N)+potassium (K)+0xP, (iii) N+K+1xP, and (iv) N+K+3xP. Phosphorus rates were 21.3 and 63.9 kg ha(-1) yr(-1) the first year and 7.1 and 21.3 kg ha(-1) yr(-1) the following 2 yr. Each fertilizer treatment was evaluated with clippings removed or clippings recycled back to the turf. In the first year, P runoff increased with increasing P rate and P losses were greater in runoff from frozen than nonfrozen soil. In year 2, total P runoff from the no fertilizer treatment was greater than from treatments receiving fertilizer. This was because reduced turf quality resulted in greater runoff depth from the no fertilizer treatment. In year 3, total P runoff from frozen soil and cumulative total P runoff increased with increasing P rate. Clipping management was not an important factor in any year, indicating that returning clippings does not significantly increase P runoff from turf. In the presence of N and K, P fertilization did not improve turf growth or quality in any year. Phosphorus runoff can be reduced by not applying P to high testing soils and avoiding fall applications when P is needed.

Potential Contributions of Mature Prairie and Turfgrass to Phosphorus in Urban Runoff

“…Total P loads in runoff from prairie were 0.14 and 0.79 kg ha −1 in Years 1 and 2, whereas the loads for turf were 0.03 and 0.52 kg ha −1 (Table 2). These TP loads for prairies and turfgrass are within the ranges reported by other researchers for these plant communities in comparable climates but lower than the TP range reported by Soldat and Petrovic (2008) for natural precipitation plot‐scale runoff studies (White and Williamson, 1973; Timmons and Holt, 1977; Steinke et al, 2007, Bierman et al, 2010). Factoring in mean runoff volumes, prairie and turf vegetation averaged 0.015 and 0.006 kg TP mm −1 of runoff, respectively, over the 2‐yr study period.…”

“…The effectiveness of P bans for turfgrass management is debatable. Fertilizer P applications under the climatic conditions of the upper Midwest have not consistently increased lawn runoff P loads (Kussow, 2008;Bierman et al, 2010). The data of Bierman et al (2010) suggest that fertilizer P rates need to be approximately three times those recommended to consistently increase runoff P loads.…”

Groundwater monitoring at the watershed scale: An evaluation of recharge and nonpoint source pollutant loading in the Clear Creek Watershed, Iowa

“…However, Easton and Petrovic (2008) found that in fertilized lawns, whereas shallow soils had the highest dissolved P losses, deeper soils had dissolved P losses similar to barren and wooded areas. Bierman, Horgan, Rosen, Hollman, and Pagliari (2010) reported that increased P losses from turf were often related to poor turf quality and growth. In our study, we focused exclusively on OP Similar to OP, we found higher Cl − m concentrations and yields in urban and suburban areas than in row crop or perennial areas (Table 2).…”

Phosphorus Availability In Turfgrass Root Zones After Applications of Organic and Synthetic Nitrogen Fertilizers

“…Because of concerns about phosphorus effects on eutrophication of surface waters, local and/or state governments New Jersey, Maine, Florida, Wisconsin, Minnesota, and Washington have adopted restrictions on residential use of phosphorus‐containing fertilizers (8,18,19,20). Urban and suburban lawns pose a specific concern for potential P loss, because managed turfgrass often abuts impermeable surfaces such as sidewalks, driveways, and curbs, which provide a direct conduit for P transport to storm drains and surface water (1).…”