Phosphorus Losses from Grasslands Fertilized with Broiler Litter: EPIC Simulations

Abstract

Broiler litter, a mixture of poultry excreta and bedding material, is commonly used to fertilize grasslands in the southeastern USA. Previous work has shown that under certain situations, application of broiler (Gallus gallus domesticus) litter to grasslands may lead to elevated levels of phosphorus (P) in surface runoff. The EPIC simulation model may be a useful tool to identify those situations. This work was conducted to evaluate EPIC's ability to simulate event and annual runoff volume and losses of dissolved reactive phosphorus (DRP) from tall fescue (Festuca arundinacea Schreb.)-bermudagrass [Cynodon dactylon (L.) Pers.] paddocks fertilized with broiler litter. The EPIC simulations of event runoff volume showed a trend toward underestimation, particularly for runoff events >30 mm. On an annual basis, EPIC also tended to underestimate runoff, especially at runoff volumes > 100 mm. Both event and annual runoff estimations were strongly associated with observed values, indicating that model calibration could improve the simulation of surface runoff volume. The relationship between simulated and observed values of DRP loss was relatively poor on an event basis (r=0.65), but was stronger (r=0.75) on an annual basis. In general, EPIC tended to underestimate annual DRP losses. This underestimation was apparently caused by the lack of an explicit mechanism to model broiler litter on the soil surface. These results suggested that additional work on the EPIC P submodel would be warranted to improve its simulation of surface application of broiler litter to grasslands.

Evaluation of Epic for Assessing Crop Yield, Runoff, Sediment and Nutrient Losses From Watersheds With Poultry Litter Fertilization

“…EPIC has been applied throughout the U.S. and many other countries (Bernardo et al, 1993;Sugiharto et al, 1994;King et al, 1996;Potter et al, 1998;Brown and Rosenberg, 1999;Pierson et al, 2001;Bernardos et al, 2001;Rinaldi, 2001;Chung et al, 2002;Apezteguía et al, 2002). The model has been integrated into the Resources and Agricultural Policy System (RAPS) designed to evaluate the economic and environmental impacts of agricultural polices for the north central U.S. (Babcock et al, 1997).…”

Historical Development and Applications of the EPIC and APEX models

“…Edwards Crop yields; N runoff losses and organic N losses; 1,500 EPIC simulations that were representative of region Atwood et al (1999) et al (1994) found that annual EPIC estimates of nutrient losses were significantly correlated with measured values, except for nitrate-N. Relatively strong agreement was found by Pierson et al (2001) between EPIC-predicted and measured phosphorus (P) losses in runoff, but predictions for single events were not as accurate. Long-term trends were accurately predicted by EPIC for conditions at Treynor, Iowa (Chung et al, 1999), although predicted annual losses were not as accurate.…”

“…Example applications include assessment of sediment and nutrient losses as a function of different tillage systems, crop rotations, and fertilizer rates King, Richardson, and Williams 1996); nutrient losses from livestock manure applications (Edwards et al 1994;Pierson et al 2001); nitrate-nitrogen (NO 3 -N) losses through subsurface tile drainage (Chung et al 2001;Chung et al 2002); nutrient cycling as a function of cropping system (Cavero et al 1999;Bernardos et al 2001); soil loss due to wind erosion (Potter et al 1998;Bernardos et al 2001); climate change impacts on crop yield and/or soil erosion (Favis-Mortlock et al 1991;Brown and Rosenberg 1999); losses from field applications of pesticides (Williams, Richardson, and Griggs 1992;Sabbagh et al 1992); irrigation impacts on crop yields (Cabelguenne, Jones, and Williams 1995;Rinaldi 2001); estimation of soil temperature (Potter and Williams 1994;Roloff, de Jong, and Nolin 1998a); and soil carbon sequestration as a function of cropping and management systems (Lee, Phillips, and Liu 1993;Apezteguía, Izaurralde, and Sereno 2002). The flexibility of EPIC has also led to its adoption within several integrated economic and environmental modeling systems that have been used to evaluate agricultural policies at the farm, watershed, and/or regional scale (e.g., Taylor, Adams, and Miller 1992;Bernardo et al 1993;Foltz, Lee, and Martin 1993;Babcock et al 1997).…”

Re-defining and quantifying inorganic phosphate pools in the soil and water assessment tool

“…Intensive manure applications in these areas often exceed the capacity of the soils to retain nutrients. Repeated applications of excess manure can increase P losses in runoff (Sharpley et al, 2001;Pierson et al, 2001) to stream and river waters, with significant consequences for downstream water quality.…”