System for value-added export of manure nitrogen and phosphorus through turfgrass sod

System for value-added export of manure nitrogen and phosphorus through turfgrass sod

Summary

The environmental and economic feasibility of using and exporting manure nutrients through turfgrass sod productions were evaluated through plot- and pilot-scale trials, simulation modeling, and economic analyses. Three meetings of SARE project participants showcased production practices and feasibility analyses for producers and various state agencies during 2002. Plot-scale studies indicated runoff and leaching losses of manure P and N imported with manure-grown sod were no greater than imported sod grown with inorganic fertilizer. Project participants are collaborating in pilot-scale monitoring of P and N export through sod and losses through runoff and leaching. A joint venture between a dairy and a sod producer on the project yielded the first commercial harvest and transplanting of manure-grown sod during October, 2002.

Objectives/Performance Targets

1.) Expand and sustain the learning system of stakeholders during development and evaluation of an infrastructure for using and adding value to manure sources of N and P.
2.) Develop and evaluate an integrated dairy and turfgrass system that will use and minimize losses of manure sources of N and P during sod production, export, and transplanting.
3.) Analyze and evaluate the operational and economical feasibility of exporting manure sources of N and P from watersheds through turfgrass sod.

Accomplishments/Milestones

Learning system. Three meetings among project participants occurred during 2002. The first meeting was scheduled in Collin county, Texas and included a tour of a joint venture between project members Sam Peterson (Gardner Turfgrass, Inc.) and Mark Quinn (Stoney Point AgriCorp., Inc.). In their collaborative business venture, manure and wastewater from a confined animal feeding operation managed by Quinn were used in production of Zoysiagrass turf established and managed by Peterson. In the second meeting, county-level extension agents, representatives of regional and state regulatory and water oversight agencies, and dairy and turf producers were invited to join project members in a workshop format. The workshop included an overview of research results, recommendations for manure management on turfgrass, and economic and logistical assessments of exports of manure N and P through sod production. A tour of research and demonstration plots on the Texas A&M University Research Center and Harold Pack dairy illustrated responses of Tifway bermudagrass and Reveille Bluegrass turf to manure and fertilizer management. A third and concluding meeting among project participants occurred during the Texas A&M University Turfgrass Field Day at College Station, Texas in September. The Field-day tours included demonstrations and presentations concerning use and export of composted dairy manure through Zoysiagrass sod. In addition to research and education functions, the learning system of project members contributed to planning and proposals for research to the Texas Cattle Feeder’s Association and the USDA National Research Initiative Competitive Grants Program.

Sod responses in replicated plots. The final harvests of ‘Tifway’ bermudagrass and ‘Reveille’ bluegrass sod produced with varying rates of composted dairy manure and fertilizer applications were sampled during Summer and Fall, 2002. Application of supplemental N fertilizer (200 kg N/ha/yr) with P rates of 100 and 200 kg P/ha in composted dairy manure achieved more rapid regrowth rates than applications of manure only and yielded three sod crops since the first harvest in 1999. The time required for regrowth between harvests was comparable for sod produced with composted manure plus N fertilizer and sod fertilized with conventional rates of N, P, and K fertilizer. Net P export through sod harvests over that of unfertilized controls totaled more than 300 kg P/ha over three years. The total P export/ha through three sod harvests of Tifway bermudagrass equaled the total annual P amount excreted in manure of more than 30 milk cows.

Sod responses in pilot-scale demonstrations. Pilot-scale fields of ‘Tifway’ bermudagrass and ‘Reveille’ bluegrass were established on the Texas A&M University Research Farm at College Station, TX and near confined dairy feeding operations on the Upper North Bosque and Trinity River watersheds in central Texas. Turfgrass America provided logistical support and collaborated in establishment of Tifway bermudagrass produced with manure P or fertilizer P at College Station. Fields were tilled, isolated by soil berms, and equipped with automated equipment for monitoring and sampling surface runoff. In addition, nutrient concentrations in groundwater wells within each field are sampled and measured. One field received 75 kg P/ha as composted dairy manure and P fertilizer raised extractable soil P to 100 kg P/ha on the other field. The first harvest of the paired sod fields is scheduled in May, 2003. Soil physical and chemical properties and turf quality are monitored to quantify soil and turf responses to composted manure.

Both Tifway bermudagrass and Reveille bluegrass sods were established on Harold Pack’s dairy. The second sod harvest was sampled during 2002. Total N and P exported in each sod harvest will be quantified for three treatments applied on each species: 1.) Control or no nutrients added, 2.) 200 kg P/ha applied as composted manure, and 3.) 200 kg P/ha applied as composted manure plus two applications 50 kg N/ha as ammonium nitrate. In addition, the plots were showcased during a workshop tour in May, 2002.

The first harvest of Zoysiagrass sod produced through collaboration between Gardner Turfgrass, Inc. and Stoney Point AgricCorp., Inc. was transplanted to the Colonial Country Club in Dallas, Texas during October, 2002. Prior to harvest, sod was sampled to estimate P and N exports from production fields and imports on the golf course.

Replicated lysimeters. John Hay, a graduate-student member of our learning system, investigated leaching losses of N and P from layers of transplanted Tifway 419 bermudagrass sod grown with composted manure or fertilizer and a layer of composted dairy manure applied on newly-sprigged turf within box lysimeters (1.3 x 1.3 x 0.6 m). Four replications of the three treatments were installed on a loamy sand soil that met United States Golf Association specifications for greens construction. Leachates were collected through a sampling tube in a horizontal length of slotted PVC pipe (5-cm diameter) at the bottom of lysimeters (0.6 m depth) and from a vertically-oriented length of 0.3-m diameter PVC pipe 20 cm below the turf surface. The base of the vertical PVC cylinder was fitted with a drain and collection tube for suction sampling.

Imported sod was produced with 200 kg manure P/ha plus N fertilizer or 50 kg fertilizer P/ha before transplanting on lysimeters. Composted manure provided 100 kg P/ha on the newly sprigged treatment. Leachates were sampled after application of 3 cm of irrigation water 1, 4, and 7 weeks after import of sod or composted manure. Fertilizer N (25 kg/ha) was applied on each treatment after the initial leaching event. A second phase of leaching events was imposed 1, 4, and 7 weeks after application of 100 kg manure P/ha on transplanted sod produced with manure and the sprigged treatment. In addition, 50 kg/ha fertilizer P was applied to transplanted sod produced with fertilizer. Similar to the first set of leaching events, 25 kg fertilizer N/ha was applied after the initial leaching event of the latter set.
Total and molybdate reactive P and nitrate in soil water samples and in five depth intervals of lysimeter soil are currently being analyzed to quantify leaching from the turf layer.

Replicated runoff plots. In addition to measurements of bermudagrass (Cynodon dactylon var. Guymon) turf responses during regrowth, volumes and P and N concentrations of surface runoff were monitored during turf reestablishment after sod harvest and after import of sod produced with manure or fertilizer. Concentrations and losses of total dissolved P and N in runoff from six replicated treatments were monitored during Fall and Spring of 2000 to 2001on an 8.5% slope of a Booneville soil (Table 1). Three treatments comprised imported ‘Tifway’ bermudagrass sod grown with either composted dairy manure (382 or 191 kg P/ha) or fertilizer (50 kg P/ha). In addition, three sprigged treatments were top-dressed with either composted manure (92 or 184 kg P/ha) or fertilizer (100 kg P/ha) after planting. Established bermudagrass provided a control. Manure P rates top-dressed on sprigged turf were smaller than amounts imported in manure-grown sod, but total dissolved P concentrations in runoff were two times greater for the sprigged treatments during eight Fall rain events. Similarly, total dissolved P losses from sprigged treatments top-dressed with manure or fertilizer were two times greater than from imported sod grown with manure during the initial runoff event during Fall. Percentages of manure P lost as total dissolved P in runoff from imported sod were one third of percentages lost from sprigged treatments top-dressed with composted manure. Sod grown with manure P rates of 190 kg P/ha can be imported without increasing potential runoff losses of total dissolved P over turf established with conventional fertilization practices.

Runoff losses from pilot-scale plots. Automated samplers were used to collect runoff samples before and after composted manure applications on the paired fields established on the Texas A&M University Research Farm during Fall and Winter, 2002.

Operational and economic feasibility. Jeremy Hanzlik, a graduate student participant in the project group, evaluated the potential land area available for turf production and watershed-scale exports of manure P through sod for the Upper North Bosque River Watershed in central Texas. Using geographic information systems (GIS), a geospatial database was developed with available data from government and institutional sources to quantify the land area suitable for turfgrass sod production on the Upper North Bosque River watershed. Sod producers could use the GIS maps of land areas proximate to dairy feeding operations for land acquisition and business development. As part of the GIS evaluation, sites identified through GIS were visited to verify suitability for sod production. The field observations were essential for refining the GIS database and maps. The ground-truthing indicated field observations of slope and contiguous acreage were as important as national soil databases for site selection through analysis of the geospatial database. A total of 71 potential sod production sites were identified through GIS analysis and visually verified through site visits. The total land area of sites comprised 5219 ha in Erath county, the central county for dairy feeding operations in Texas. An ample supply of land was available for turfgrass sod production in close proximity to supplies of composted dairy manure.

Drs. Wolfe and Bosche, subcontractors from Virginia Tech, continued their evaluations of nonpoint-source simulation models for predictions of P and N losses through runoff and leaching. Simulations of the GLEAMS model were compared to runoff observations for bermudagrass sod that received applications of composted dairy manure or inorganic fertilizer from Fall 1998 to Spring 2000. Input data files for simulations were constructed from data for experimental treatments (soil type, size, type of grass, mowing) on the 8.5% slope of bermudagrass. During 2002, simulations emphasized prediction of nutrient losses from newly sprigged treatments and transplanted sod grown with composted dairy manure or inorganic fertilizer. Earlier runs conducted with the GLEAMS model were refined through improved parameter estimation. The model was calibrated successfully for runoff, which allowed model predictions of nutrient losses to be evaluated independent of the runoff estimates. GLEAMS predicted dissolved losses for all events fairly well except for the Spring 1999 time period. Poor predictions for one event affected the results for the whole time period. In general, N losses were predicted more accurately than P losses. In addition, model simulations underestimated nutrient losses for all treatments. Based on the overall results, it appears that GLEAMS could be used to evaluate losses from newly established sod.

Economic analyses. Dr. Curtis Lard has developed enterprise budgets comparing sod production costs and returns between fertilizer and manure sources of nutrients and between sites near and distant from sources of composted dairy manure. The purchase cost for rates of composted dairy manure ($10.00/ cu. yd.) needed to achieve multiple objectives of the system for manure export through sod increased unit costs of nutrients 10-fold compared to fertilizer (Table 2). Clearly, the cost of reducing nutrient loads on impaired watersheds will need to be divided among dairy, composted-manure, turf producers, and perhaps other stakeholders. The value added through large rates of composted manure on sod, including potential increases in water holding capacity and long-term supplies of nutrients after sod is transplanted, could be captured in the wholesale price per cu. yd. of sod. Yet, sales of manure-grown sod can cover part but not all of the costs of large rates of composted manure during production and P export from impaired watersheds. In addition, hauling costs increased unit costs of manure nutrients as the distance between sod production sites and sources of composed dairy manure increased.

Drs. Bosch and Wolfe modified enterprise budgets developed for sod production in Texas for analyses of Virginia conditions. The economic feasibility of using dairy manure in place of inorganic fertilizer was evaluated (Table 3). Unlike the Texas comparison, manure applications were limited to rates that supplied recommended N or P requirements for turfgrass growth. Costs and returns for sod produced with dairy manure were similar to that produced with conventional fertilizer rates. If dairy manure applied on land owned by a dairy was free, inorganic fertilizer expenses for N, P, and potassium (K) for conventional sod production were greater than manure. For both budgets, some inorganic nutrients were needed to ensure premium quality of the sod.

The economic feasibility of incorporating a sod operation into a dairy farm was investigated for a representative farm in Virginia. Two alternatives, dairy production with and dairy without sod, were compared in the context of two nutrient application scenarios; one scenario utilized N-based application rates while the second scenario utilized P-based application rates. The representative Virginia dairy, located in a dairy producing area in the Shenandoah Valley, comprised 100 cows with an additional 30 to 40 replacement heifers. For the dairy operation with a sod enterprise, 50 acres was taken out of corn silage production and put into sod.

For the sod enterprise on the dairy, additional income was calculated based on the wholesale price of sod per yard, assuming 85% of the sod would be harvested. Reduced expenses were associated with savings on labor, equipment, and materials associated with the 50 acres taken out of corn silage to produce sod. Increased expenses included purchase of corn silage to replace that previously grown on the 50 acres and expenses associated with the sod enterprise. The amount and cost of dairy manure that would need to be hauled off the farm was calculated for the dairy enterprise alone and for the dairy with the sod enterprise if nutrient management switched from N to P based on P crop removal for corn silage. Initial analyses estimated an additional $38,920 in profits during a typical year for the dairy with sod enterprise compared to the dairy alone when manure was applied on an N basis. An additional profit of $46,209 was estimated for P-based applications. Additional detailed analyses are being conducted to improve estimates.

Impacts and Contributions/Outcomes

The learning system of this project has developed new research information, guidelines for manure and nutrient management during sod production, estimates of environmental impacts of manure exports and imports through sod, and collaborative ventures between livestock and turf producers. For example, the joint venture in Zoysiagrass sod production between Gardner Turfgrass, Inc. and Stoney Point AgriCorp., Inc. emerged from research studies and critical conversations among participants in this project. Joint ventures between livestock and turf producers have forged new pathways for exporting manure P and N from impaired to less impacted watersheds and between industries that previously operated independently. The turf production and export system of this project is providing an alternative to government-subsidized exports of composted manure from impaired watersheds in Texas. In addition, imports of composted dairy manure in a sod product will reduce potential runoff losses of P compared to surface applications of inorganic P fertilizer or composted dairy manure on establishing turf.

Collaborators: