Georgia Water Resources Conference

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Georgia Water Resources Conference

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Georgia Water Resources Institute

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AWARE Team Activities in Georgia

(Georgia Institute of Technology, 1999-03) Risse, L. Mark ; Radcliffe, David E. ; Harris, Glen ; Newton, G. Larry ; Worley, John ; Cabrera, Miguel L.

This paper will discuss the development of the AWARE (Animal Waste Awareness in Research in Extension) team and some of its recent activities. It will cover the goals of the team and how it functions to obtain these goals. It will also discuss some of the tools the team uses including the webpage, listserve, and meetings and discuss how they are helping people throughout the state with information exchange on animal waste management issues. It will also discuss some of the AWARE teams past activities and plans for future activities.
Grazing Management Effects on Surface Runoff from Pastures Fertilized with Broiler Litter

(Georgia Institute of Technology, 1999-03) Kuykendall, Holli ; Cabrera, Miguel L. ; Hoveland, Carl ; McCann, Mark ; West, Larry

Repeated heavy applications of broadcast broiler litter can increase nutrient nmoff from pastures. Rotational stocking of cattle, as compared to continuous stocking, may be useful in decreasing surface nutrient runoff because of better manure . distribution and more uniform forage accumulation to act as filters and trap nutrients. The objective of this study was to measure phosphorus runoff from six 0.75- ha (6-8% slope) endophyte-infected tall fescuecommon bermudagrass pastures that were fertilized with 13 to 15 Mg (dry weight) ha-1 yr-1 broiler litter. Runoff was analyzed for dissolved reactive P (DRP) and total Kjeldahl P (TKP). Grazing method had no effect (P>0.10) on surface runoff quality or quantity. The average flow weighted concentration of DRP for both stocking treatments was 5.1 mg P L-1 for the first year and 8.2 mg P L-1 for the second year {P<0.10). The flow weighted concentration of TKP was 6.8 mg P L-1 for the first year and 12.8 mg P L-1 for the second year (P<0.10). A substantial portion of the second year nutrient loss came from a single runoff event that occurred just two days after the third broiler litter application.
Land Model: A Simulation Tool for Estimating the Nutrient Dynamics from Land-applied Animal Manure

(Georgia Institute of Technology, 1999-03) Hitchcock, Daniel R. ; Cabrera, Miguel L. ; Smith, Matt C.

The primary objective of this study is to develop a simulation model for predicting nutrient fluxes from the land application of animal waste, resulting in the Land Application Nutrient Dynamics (LAND) model. The simulation model is being developed in STELLA® software focusing on the following processes: 1) microbial decomposition of biomass and organic waste constituents; 2) the plant uptake of nutrients, and 3) the volatilization, assimilation, runoff, and leaching of nitrogen compounds. Model structure is based on the PHOENIX model for carbon and nitrogen dynamics in grassland soils with modifications for hydrological processes. Model parameterization and calibration were based on literature values and published data. This model could aid in a better understanding of the physical, chemical, and biological processes that determine the fate and transport of nutrients, mainly carbon and nitrogen, upon application of animal waste to grassland field systems. This should also aid in developing effective nutrient management strategies for confined animal feeding operations (CAFOs). Preliminary information is presented in this paper.
Differences of Soil Water Use, Lint and Biomass Yield in No-till and Conventionally Tilled Cotton in the Southern Piedmont

(Georgia Institute of Technology, 1999-03) Endale, Dinku M. ; Radcliffe, David E. ; Steiner, Jean L. ; Cabrera, Miguel L. ; McCracken, D. V. ; Vencill, B. V. ; Lhor, L. ; Schomberg, H. H.

The southeast, despite its abundant rainfall, suffers short-term summer droughts with detrimental effect on crop yield. No-till production systems provide added insurance against such conditions by improving infiltration, and conserving moisture in drought-prone soils. In three years of experiment near Watkinsville, GA, no-till cotton treatments maintained higher soil moisture content, more vegetative growth and higher lint yield than conventional tillage treatments. A combination of no-till and poultry litter treatments did even better compared to conventional tillage and conventional fertilizer treatments.
Evolution of Phosphorus Concentration in Surface Runoff from Pastures Fertilized with Broiler Litter

(Georgia Institute of Technology, 1999-03) Kuykendall, Holli ; Hoveland, Carl ; McCann, Mark ; Cabrera, Miguel L.

Previous research has shown that surface application of broiler litter to pastures can lead to elevated concentrations of dissolved reactive phosphorus (DRP) in surface runoff. It is not clear, however, for how long a after broiler litter application DRP concentrations in runoff remain high. This work was conducted to study the evolution of DRP concentration in surface runoff from pastures that received broiler litter in 1995 and 1996, and only inorganic fertilizer Nin 1997 and 1998. The results showed that DRP concentrations in surface runoff remained high (> 2 mg P L-1) while broiler litter was being applied. Once broiler litter applications stopped, DRP concentrations in runoff decreased below 1 mg p L-1 within 19 months. These results suggest that the risk of contaminating surface waters with DRP could be decreased by fertilizing pastures with broiler litter every two or three years, with the addition of only fertilizer N in those years when broiler litter is not applied.
Field Trials of Alum Amendment of Broiler Litter to Reduce Soluble Phosphorus

(Georgia Institute of Technology, 1999-03) Worley, John W. ; Cabrera, Miguel L.

Aluminum sulfate (alum) has been demonstrated to reduce ventilation and heating requirements by lowering pH and thus reducing ammonia release from broiler litter during brooding of broiler chickens raised on previously used litter. It also has been shown to reduce runoff of phosphorus from fields where litter is applied, and increase nitrogen levels in treated litter. Most previous research, however, has been done in locations and under different litter management than is common in Georgia. This research compared broiler houses in North Georgia operated under a common management scheme with other houses using alum amendment of the litter. The second stage compared houses with alum added at full rate with others where alum was added at half the recommended rate. This research demonstrated that much of the economic benefit of adding alum can be achieved by adding only half the recommended rate. Soluble phosphorus and ammonium nitrogen levels were adversely affected by reducing application rates. While the environmental benefit of phosphorus runoff reduction would be lessened by adding less alum, an advantage may be realized industry wide by reducing the application rate since more growers would be likely to use it due to economic benefits.
Evaluation of a Small, In-field Runoff Collector

(Georgia Institute of Technology, 1999-03) Franklin, Dorcas ; Cabrera, Miguel L. ; Steiner, Jean L. ; Endale, Dinku M. ; Miller, William

Increased environmental concern about surface water pollution has heightened the need for small, in-field runoff collectors to assess the impact of land management practices without altering the landscape. We modified a surface flow sampler designed for sheet flow in Coastal Plain soils. Modifications were made to accommodate steep slopes (3 to 15% ), large flow rates, and channelized flow which are common in the Southern Piedmont. The runoff collector consists of two sample splitters (10x and 100x) and two sample collectors. Runoff collector performance was evaluated in the laboratory to determine percent flow captured by 10x and 100x splitters relative to flow rate and slope. Average flow captured on a 5% slope was 10.3% for 10x and 1.8% for the l00x. When the slope was increased to 12% the percent flow capture also increased slightly, 10.4% for l0x and 2.3% for l00x. It was determined that the small, in-field runoff collector captures runoff volumes at specific rates at fairly consistent ratios.
N and P Edge-of-field Losses from Poultry Litter Applications

(Georgia Institute of Technology, 1997-03) Vervoort, R. W. ; Radcliffe, David E. ; Cabrera, Miguel L. ; Latimore, M., Jr.

Excess application of poultry litter may cause pollution of surface and ground water with Nitrogen (N) and Phosphorus (P). Composting poultry litter could reduce the risk of pollution by creating more stable organic components. Three rates of poultry litter and compost (10 Mg he litter, 20 Mg he litter and 10 Mg he litter combined with 50 Mg ha' compost) to three watersheds under pasture. The watersheds were monitored for surface and subsurface flow. Nitrate concentrations in subsurface flow did not exceed the U.S. Environmental Protection Agency drinking water standard of 10 mg Soluble P concentrations in runoff were high, reaching a maximum of 8.5 mg L4 under the compost treatment. Concentrations of P in soil in the top 15 cm increased dramatically under the compost treatment which creates a high potential for future runoff of P. Total losses of N and P were low, mainly due to few runoff and subsurface events.
Nitrogen Release from Land-applied Animal Manures

(Georgia Institute of Technology, 1995-04) Cabrera, Miguel L. ; Gordillo, R. M.

Animal manures are a valuable source of nitrogen (N) for crops. However, not all N in manure is available to plants. In general, manure N in inorganic form is immediately available to plants, although some inorganic N may be lost through ammonia volatilization and denitrification, and some may be immobilized by microorganisms. Another fraction of manure N available to plants is that proportion of organic N that is mineralized within a crop’s growing season. This mineralized N is also susceptible to losses through ammonia volatilization and denitrification, and to immobilization by soil microorganisms. Thus, to determine the correct N-supplying capacity of animal manure it is necessary to know the amounts of inorganic and organic N present in the manure, the fraction of organic N that is mineralizable, and the magnitude of processes that decrease the availability of released N.
Estimating Nitrate Leaching and Soil Water Dynamics with LEACHM

(Georgia Institute of Technology, 1993-04) Johnson, A. D. ; Cabrera, Miguel L. ; Hargrove, William L. ; McCracken, D. V. ; Harbers, G. W.