Comparing Phosphorus Indices from Twelve Southern U.S. States against Monitored Phosphorus Loads from Six Prior Southern Studies

Osmond, Deanna L.; Sharpley, Andrew N.; Bolster, Carl H.; Cabrera, M. L.; Feagley, S. E.; Lee, B.; Mitchell, Charles C.; Mylavarapu, Rao; Oldham, J. Larry; Walker, Forbes; Zhang, Hailin

doi:10.2134/jeq2012.0013

Cited by 27 publications

(32 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A description of the 12 southern P Indices can be found in Osmond et al (2012). Indices, however, can be generally defined as additive, multiplicative, and component.…”

Section: Methodsmentioning

confidence: 99%

“…Thirty‐four input variables were assembled from each site to serve as inputs to the various P Indices (Osmond et al, 2006; Osmond et al, 2012). Some factors, however, were not available and had to be assumed: water resource impairment, buffer (since all collected data were edge of field), irrigation, rock fragments > 25.4 cm, and infrequent flooding.…”

Section: Methodsmentioning

confidence: 99%

“…Some states modified the original P Index (Lemunyon and Gilbert, 1993), while other states, such as Arkansas, Georgia, and North Carolina, used different strategies to develop their P Index (Osmond et al, 2006). Not surprisingly, state P Index recommendations vary widely (Osmond et al, 2006, 2012; Sharpley et al, 2003). Osmond et al (2006) compared P Indices from 12 southern US states and found that there were diverse P Index ratings between states for the same conditions, which led to differences in P management and the amount of animal manures, effluents, and fertilizer allowed.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Southern Phosphorus Indices, Water Quality Data, and Modeling (APEX, APLE, and TBET) Results: A Comparison

et al. 2017

View full text Add to dashboard Cite

Phosphorus (P) Indices in the southern United States frequently produce different recommendations for similar conditions. We compared risk ratings from 12 southern states (Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, and Texas) using data collected from benchmark sites in the South (Arkansas, Georgia, Mississippi, North Carolina, Oklahoma, and Texas). Phosphorus Index ratings were developed using both measured erosion losses from each benchmark site and Revised Universal Soil Loss Equation 2 predictions; mostly, there was no difference in P Index outcome. The derived loss ratings were then compared with measured P loads at the benchmark sites by using equivalent USDA-NRCS P Index ratings and three water quality models (Annual P Loss Estimator [APLE], Agricultural Policy Environmental eXtender [APEX], and Texas Best Management Practice Evaluation Tool [TBET]). Phosphorus indices were finally compared against each other using USDA-NRCS loss ratings model estimate correspondence with USDA-NRCS loss ratings. Correspondence was 61% for APEX, 48% for APLE, and 52% for TBET, with overall P index correspondence at 55%. Additive P Indices (Alabama and Texas) had the lowest USDA-NRCS loss rating correspondence (31%), while the multiplicative (Arkansas, Florida, Louisiana, Mississippi, South Carolina, and Tennessee) and component (Georgia, Kentucky, and North Carolina) indices had similar USDA-NRCS loss rating correspondence-60 and 64%, respectively. Analysis using Kendall's modified Tau suggested that correlations between measured and calculated P-loss ratings were similar or better for most P Indices than the models. (Dubrovsky and Hamilton, 2010). Recent harmful algal blooms in Lake Erie caused Toledo to shut down its drinking water supply for several days, refocusing the link between nutrient enrichment (particularly phosphorus [P]) and water quality impairment (Stow et al., 2015), with many of these nutrients being agriculturally derived. To control agricultural nutrient loading to surface waters, multiple control strategies are necessary at the source and during transport into the receiving water resources. The USDA-NRCS refers to this as "avoid, control, and trap."Since the late 1990s, the USDA and USEPA jointly required all states to adopt a unified nutrient management policy through the NRCS Code 590 Standard (USDA and USEPA, 1999). States were required to establish a soil-test P threshold based on crop requirements (above which P applications were restricted), to establish an alternative soil test P threshold using water quality criteria, or to develop a P Index to identify fields at risk for P losses. Forty-eight states and some territories, including Puerto Rico, chose to use P Indices (Sharpley et al., 2003), a concept originally developed by USDA-NRCS for assigning relative risk of P loss to agricultural fields (Lemunyon and Gilbert, 1993). California and Connecticut use soil-test P crop response (Sharpley et al., 2003).To...

show abstract

“…A description of the 12 southern P Indices can be found in Osmond et al (2012). Indices, however, can be generally defined as additive, multiplicative, and component.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Southern Phosphorus Indices, Water Quality Data, and Modeling (APEX, APLE, and TBET) Results: A Comparison

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Performance of the Ohio PI was similar to other state PIs evaluated in the literature. For example, Osmond et al (2012) evaluated 12 southern‐state PIs against previously published field data. They found that 5 of the 12 PIs had a moderate to strong ( R 2 = 0.50–0.97) relationship between PI score and TP load, and all but one of the PIs was directionally correct.…”

Section: Discussionmentioning

confidence: 99%

Edge‐Of‐Field Evaluation of the Ohio Phosphorus Risk Index

et al. 2017

View full text Add to dashboard Cite

The Phosphorus Index (PI) has been the cornerstone for phosphorus (P)-based management and planning over the past twenty years, yet field-scale evaluation of many state PIs has been limited. In this study, P loads measured in surface runoff and tile discharge from 40 agricultural fields in Ohio with prevailing management practices were used to evaluate the Ohio PI. Annual P loads were highly variable among fields (dissolved reactive P: 0.03-4.51 kg ha, total P: 0.03-6.88 kg ha). Both measured annual dissolved reactive P ( = 0.36, < 0.001) and total P ( = 0.25, < 0.001) loads were significantly related to Ohio PI score. The relationship between measured load and PI score substantially improved when averaged annual field values were used (dissolved reactive P: = 0.71, total P: = 0.73), indicating that the Ohio PI should be utilized to evaluate average annual risk of P loss, rather than as an annual risk tool. Comparison between the Ohio PI and other established local and national metrics resulted in large differences in potential P management recommendations for the monitored fields. In the near term, revision of Ohio PI risk categories and management recommendations using local P loading thresholds is needed. To meet the minimum criteria for state PI tools, future research efforts should focus on using measured field data (i) to incorporate new input factors (i.e., P application timing and leaching potential) into the Ohio PI, and (ii) to calibrate and validate the Ohio PI to provide better P risk assessments and management recommendations.

show abstract

“…While erosion standards were originally the major tie to control P, the emergence of a joint agreement by the USEPA and USDA, followed by the promulgation of Conservation Practice 590 (Nutrient Management) standard, served as the first national rubric aimed at improving P management, resulting in widespread development of the P index by states (Lemunyon and Gilbert, 1993; Sharpley et al, 2003). The P index provides a means of assessing fields for risk of P loss across a farm, but there have been concerns over differences in its development and deployment across state lines and its efficacy in promoting management change (Osmond et al, 2012; Sharpley et al, 2012). Furthermore, it is ineffective in regions in which there is regional P excess as there are few options to divert manure applications out of the impacted area.…”

Section: Watershed Phosphorus Concerns Across Latitudesmentioning

confidence: 99%

The Latitudes, Attitudes, and Platitudes of Watershed Phosphorus Management in North America

et al. 2019

View full text Add to dashboard Cite

Phosphorus (P) plays a crucial role in agriculture as a primary fertilizer nutrient—and as a cause of the eutrophication of surface waters. Despite decades of efforts to keep P on agricultural fields and reduce losses to waterways, frequent algal blooms persist, triggering not only ecological disruption but also economic, social, and political consequences. We investigate historical and persistent factors affecting agricultural P mitigation in a transect of major watersheds across North America: Lake Winnipeg, Lake Erie, the Chesapeake Bay, and Lake Okeechobee/Everglades. These water bodies span 26 degrees of latitude, from the cold climate of central Canada to the subtropics of the southeastern United States. These water bodies and their associated watersheds have tracked trajectories of P mitigation that manifest remarkable similarities, and all have faced challenges in the application of science to agricultural management that continue to this day. An evolution of knowledge and experience in watershed P mitigation calls into question uniform solutions as well as efforts to transfer strategies from other arenas. As a result, there is a need to admit to shortcomings of past approaches, plotting a future for watershed P mitigation that accepts the sometimes two‐sided nature of Hennig Brandt's “Devil's Element.” Core Ideas North American P mitigation experiences spanning 26 degrees of latitude are explored. Uncertainty and lag times create schisms in mitigation programs. One‐size‐fits‐all approaches cannot account for management trade‐offs. Acknowledging shortcomings in messages and approaches is imperative to moving on. Unified P mitigation provides a framework and eliminates solution singularities.

show abstract

Comparing Phosphorus Indices from Twelve Southern U.S. States against Monitored Phosphorus Loads from Six Prior Southern Studies

Cited by 27 publications

References 18 publications

Southern Phosphorus Indices, Water Quality Data, and Modeling (APEX, APLE, and TBET) Results: A Comparison

Southern Phosphorus Indices, Water Quality Data, and Modeling (APEX, APLE, and TBET) Results: A Comparison

Edge‐Of‐Field Evaluation of the Ohio Phosphorus Risk Index

The Latitudes, Attitudes, and Platitudes of Watershed Phosphorus Management in North America

Contact Info

Product

Resources

About