System for Conserving and Adding Value to Manure Sources of Nutrients in Turf-grass Sod
Manure and wastewater disposal on land holdings of large dairies have contributed to phosphorus accumulation on watersheds in the Southern U.S. A learning organization comprising dairy, turfgrass, and compost producers and university research and extension faculty was assembled. This organization or ‘learning system’ focused on concerns about phosphorus loads on watersheds and the sustainability of both dairy and turf industries in the Southern Region.
The human activities of participants in the learning system during this one-year project, including four project meetings and a one-day workshop, were relevant to three project objectives:
1.) Organize the learning system
2.) Characterize turfgrass responses and the fate of nitrogen and phosphorus after surface applications of manure, and
3.) Evaluate the operational and economical feasibility of exporting manure sources of nutrients from farms and watersheds through sod.
During project meetings, participants identified information and analyses that were needed to develop and evaluate a system for exporting manure sources of phosphorus through sod. Information about responses of turfgrass establishment, production, and quality after manure application was developed in replicated plots. The production and quality of ‘Tifway’ bermudagrass and ‘Prairie’ buffalograss during the 15 months from planting to the first sod harvest was equal or better for manure compared to fertilizer sources of nutrients. Sod harvests of bermudagrass and buffalograss during summer, 1999 removed 45 to 62% of phosphorus applied as manure before and 1 year after planting. The first sod harvest indicated surface accumulations of manure phosphorus were effectively removed and exported through turfgrass sod. Manure influences on turfgrass regrowth after sod harvest and on recovery of the manure-grown sod after transplanting remain to be evaluated.
The fate of nitrogen and phosphorus after surface applications of manure and fertilizer were evaluated on common bermudagrass plots. The volume and nutrient concentration in runoff from the 8%-slope of plots was monitored after four natural rainfall events during each of two monitoring periods. Metal barriers were inserted into soil around plot perimeters and metal chutes on the down-slope end of plots channeled runoff into reservoirs. Nitrogen and phosphorus losses in runoff were compared between manure and fertilizer sources of nutrients. During a relatively large runoff event that occurred 3 days after equal phosphorus rates were applied as manure or fertilizer on the bermudagrass, the concentration of phosphorus in runoff from fertilized plots was 5.5 times greater than manured plots. Dissolved phosphorus concentrations in plot runoff were comparable between manure and fertilizer sources of equal phosphorus durng the second, third, and fourth rainfall events. Manure sources of nutrients appeared to be less soluble and less vulnerable to loss in surface runoff than fertilizer sources soon after nutrients were applied to the bermudagrass sod. Potential losses of manure and fertilizer sources of nitrogen and phosphorus from the bare soil remaining after sod harvest and from transplanted sod remain to be quantified.
Information from plot-scale studies, demonstrations on dairy fields, and project participants will be used to develop recommendations for an integrated dairy and sod production system and to identify questions and knowledge gaps for future research and development efforts. In addition, project participants will use information from this and emerging projects to evaluate the operational and economic feasibility of exporting manure sources of nutrients through turfgrass sod. The export of manure sources of nutrients through sod is expected to contribute to the economic and environmental sustainability of both livestock and turfgrass industries.
Editor’s note: This planning project resulted in a successful full project LS00-117.