Assessment of the Georgia phosphorus index on farm at the field scale for grassland management

dc.contributor.author	Butler, DM	en
dc.contributor.author	Franklin, DH	en
dc.contributor.author	Cabrera, ML	en
dc.contributor.author	Risse, LM	en
dc.contributor.author	Radcliffe, DE	en
dc.contributor.author	West, LT	en
dc.contributor.author	Gaskin, JW	en
dc.date.accessioned	2014-06-06T06:49:42Z
dc.date.available	2014-06-06T06:49:42Z
dc.date.issued	2010	en
dc.identifier.issn	00224561	en
dc.identifier.uri	http://dx.doi.org/10.2489/jswc.65.3.200	en
dc.identifier.uri	http://62.217.125.90/xmlui/handle/123456789/4737
dc.subject	Forages	en
dc.subject	Phosphorus	en
dc.subject	Phosphorus index	en
dc.subject	Runoff	en
dc.subject	Water quality	en
dc.subject.other	agricultural land	en
dc.subject.other	bioavailability	en
dc.subject.other	forage	en
dc.subject.other	grassland	en
dc.subject.other	management practice	en
dc.subject.other	pasture	en
dc.subject.other	phosphorus	en
dc.subject.other	risk assessment	en
dc.subject.other	runoff	en
dc.subject.other	surface water	en
dc.subject.other	water quality	en
dc.subject.other	Georgia	en
dc.subject.other	United States	en
dc.title	Assessment of the Georgia phosphorus index on farm at the field scale for grassland management	en
heal.type	journalArticle	en
heal.identifier.primary	10.2489/jswc.65.3.200	en
heal.publicationDate	2010	en
heal.abstract	In order to better manage agricultural phosphorus (P), most states in the United States have adopted a ""P indexing"" approach that ranks fields according to potential P losses. In Georgia, the Georgia P Index was developed to estimate the risk of bioavailable P loss from agricultural land to surface waters, considering sources of P, transport mechanisms, and management practices. Nine farm fields, managed as pasture or hay systems, were outfitted with 28 small in-field runoff collectors. Runoff P, soil P, and field management practices were monitored from 2004 to 2007. Fields varied from those rich in P (broiler litter or dairy slurry) to those without P amendments (inorganic nitrogen [N] or no amendments). Data relating to nutrient applications, soil properties, soil P, and management were used as input values to determine a Georgia P Index value estimating the risk of P export from each field. Results indicated that the Georgia P Index underrated the risk in only 2% of the cases when considering loads or mass losses of P, partly due to the influence of small annual runoff volumes and thus greater flow-weighted concentrations from some fields. While measured P export was generally low to moderate (<7.5 kg P ha-1 y-1 [<6.7 lb ac-1 yr-1]) from fields rated as a low or medium risk of P export, findings from this study indicated that the Georgia P Index, at times, overestimated the risk of P losses for hay systems and underestimated the risk of P losses for pastures when no amendments were applied.	en
heal.journalName	Journal of Soil and Water Conservation	en
dc.identifier.issue	3	en
dc.identifier.volume	65	en
dc.identifier.doi	10.2489/jswc.65.3.200	en
dc.identifier.spage	200	en
dc.identifier.epage	210	en