Terminology in soil fertility and nutrient management Extension programming has evolved with increasing society emphasis on agriculture and environment interactions. Management of nutrient phosphorus (P) is important to agricultural environmental stewardship. Primarily, the term  Phosphorus Index  has two different meanings in nutrient management planning: the traditional use describes categories of plant response in soil test recommendations; the newer use describes a method of ascribing P movement risk in the landscape. Occasionally the term is used differently in soil science than these two examples. Extension personnel, agronomists, and technical personnel should use the appropriate terms to avoid confusing clientele

Oldham, J Larry

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The Journal of Extension Volume 45 Number 1 Article 29 2-1-2007 Understanding the Different Phosphorus Indices in Nutrient Management Planning J Larry Oldham Mississippi State University, loldham@pss.msstate.edu This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 4.0 License. Recommended Citation Oldham, J. (2007). Understanding the Different Phosphorus Indices in Nutrient Management Planning. The Journal of Extension, 45(1), Article 29. https://tigerprints.clemson.edu/joe/vol45/iss1/29 This Tools of the Trade is brought to you for free and open access by the Conferences at TigerPrints. It has been accepted for inclusion in The Journal of Extension by an authorized editor of TigerPrints. For more information, please contact kokeefe@clemson.edu. 	 JOEHOME JOURNAL GUIDELINES ABOUT	JOE CONTACT NATIONAL	JOB	BANKCurrent	Issues Back	IssuesFebruary	2007	//	Volume	45	//	Number	1	//	Tools	of	the	Trade	//	1TOT60Understanding	the	Different	Phosphorus	Indices	in	NutrientManagement	PlanningAbstractTerminology	in	soil	fertility	and	nutrient	management	Extension	programming	has	evolved	withincreasing	society	emphasis	on	agriculture	and	environment	interactions.	Management	ofnutrient	phosphorus	(P)	is	important	to	agricultural	environmental	stewardship.	Primarily,	theterm	"Phosphorus	Index"	has	two	different	meanings	in	nutrient	management	planning:	thetraditional	use	describes	categories	of	plant	response	in	soil	test	recommendations;	the	neweruse	describes	a	method	of	ascribing	P	movement	risk	in	the	landscape.	Occasionally	the	term	isused	differently	in	soil	science	than	these	two	examples.	Extension	personnel,	agronomists,	andtechnical	personnel	should	use	the	appropriate	terms	to	avoid	confusing	clientele.	IntroductionExtension	professionals	perform	many	roles	in	agricultural	environment	stewardship	education,often	clarifying	information	provided	by	various	agencies	and	technical	providers,	including	theirown	universities.	This	article	reviews	soil	fertility	and	nutrient	management	issues	and	terminologythat	have	evolved	that	Extension	personnel	should	utilize	clearly	in	their	programming.The	nutrient	phosphorus	(P)	is	integral	to	livestock	and	crop	production.	Nutrient	management	ismanaging	the	amount,	source,	placement,	form,	and	timing	of	nutrient	and	soil	amendmentapplications	to	ensure	adequate	soil	fertility	for	plant	production	and	to	minimize	detrimentalenvironmental	impacts.	Nutrient	Management	Plans	(NMPs)	document	the	management	decisionsand	serve	as	an	operational	action	plan	(NRCS,	1999).	Extensive	P	research	and	outreach	activityat	the	agriculture	and	environment	interface	introduced	new	nutrient	management	terminology."Phosphorus	Index"	can	be	used	in	multiple	ways	in	the	NMP	process.Defining	Phosphorus	IndicesEnvironmental	Risk	Assessment	Phosphorus	IndexOff-target	movement	of	P	contributes	to	eutrophication	in	surface	waters,	a	nutrient	enrichedsituation	exemplified	through	increased	algae	growth;	adverse	conditions	associated	witheutrophication	include	increased	turbidity,	oxygen	depletion,	loss	of	desirable	species,	andincreased	fish	kills	(Carpenter	et	al.,	1998).	Phosphorus	moves	from	agricultural	productionsystems	via	four	mechanisms	(Lemunyon	&	Daniel,	2002):Attached	to	sediment,In	runoff	water,Leached	through	the	soil,	andRemoved	via	harvested	plants.J.	Larry	OldhamExtension	Professor	-	SoilsMississippi	State	University	Extension	ServiceMississippi	State,	Mississippiloldham@pss.msstate.eduSite-specific	source	and	transport	factors	control	the	loss	mechanisms	other	than	through	harvest:source	issues	include	soil	P	levels	and	management	of	organic	and	inorganic	fertilizers;	transportfactors	include	erosion	rates	and	runoff	properties	(Hansen,	Lemunyon,	Sharpley,	&	Daniel,	2002).Recent	research	activity	has	targeted	on	how	to	best	use	these	factors	to	evaluate	the	risk	of	Pmovement	in	the	landscape.	"Phosphorus	Index"	(NRCS,	1999)	models	are	employed	in	47n	statesin	various	forms	to	perform	environmental	risk	assessment	as	all	or	part	of	the	nutrientmanagement	planning	strategy	(Sharpley	et	al.,	2003).The	models	were	developed	in	each	state	by	researchers,	Extension,	and	agency	personnel	to	bestfit	regional	or	state	conditions	and	vary	accordingly.	A	recent	review	found	37	different	factorsutilized	in	the	Phosphorus	Indices	of	12	southern	states	(Osmond	et	al.,	2006).	Four	states,Arkansas,	Iowa,	Georgia,	and	North	Carolina,	adopted	versions	that	predict	quantities	of	Pdisplaced	under	the	various	modeled	scenarios.	Other	states	assess	the	P	loss	risk	via	qualitativeprocesses	(Osmond	et	al.,	2006;	Sharpley	et	al.,	2003).Used	during	the	nutrient	planning	process,	the	Phosphorus	Index	rates	the	propensity	as	low,medium,	or	high	for	P	movement	from	a	field	under	consideration	for	nutrient	application.	Whenthe	risk	assessment	is	medium	or	high,	either	application	rate	may	be	lowered,	alternative	fieldsused,	non-land	application	uses,	or	Best	Management	Practices	implemented	to	reduce	theenvironmental	risk.	Exploration	of	alternate	management	options	is	an	excellent	opportunity	forteaching	about	the	interface	of	agriculture	and	the	environment	between	the	NMP	preparer	andthe	client.Soil	Testing	Phosphorus	IndexSoil	testing	services	(Peck	&	Soltanpour,	1990)	are	provided	by	many	land	grant	universities	to:Accurately	determine	the	available	nutrient	status	of	soils,Clearly	indicate	whether	nutrients	are	deficient	or	sufficient,Form	the	basis	for	any	fertilizer	recommendation,	andPermit	economic	evaluation	of	fertilizer	recommendations.Soil	test	based	recommendations	rely	on	calibration	and	correlation	research.	Calibration	is	thedetermination	of	a	particular	crop	nutrient	requirement	at	different	soil	test	values;	correlationdetermines	the	relationship	between	nutrient	uptake	or	yield,	and	how	much	nutrient	is	extractedby	a	particular	soil	test	method	(Beegle,	2005).Soil	test	interpretations	for	P	use	crop	response	predictions	often	characterized	by	a	curvilineargraph	derived	from	the	calibration	process	(Fixen	&	Grove,	1990).	The	soil	test	concentration	of	aparticular	nutrient	is	plotted	along	the	abscissa;	the	ordinate	data	is	a	growth	response	variable,usually	yield.	The	resulting	curve	may	be	separated	into	regions	that	correspond	to	the	probablegrowth	response	in	changing	the	soil	test	value	through	fertilization.	These	regions	are	referred	toas	"soil	test	categories,"	or	in	some	states,	"soil	test	index."	Some	states	use	terms	such	as	"BelowOptimum,"	"Optimum,"	or	"Above	Optimum"	for	these	indices,	others	use	terms	more	quantitativeterms	such	as	"Very	Low,"	"Low,"	"Medium,"	"High,"	and	"Very	High."In	North	Carolina,	the	soil	testing	usage	is	codified	by	state	law,	thus	their	state	risk	assessment	istermed	the	more	descriptive	"Phosphorus	Loss	Assessment	Tool"	(D.	Osmond,	personalcommunication).	Soil	test	P	is	a	source	factor	in	environmental	risk	Phosphorus	Indices	(NRCS,1999),	thus	Phosphorus	Indices	are	used	within	a	Phosphorus	Index.	Using	the	soil	testinginformation	in	the	context	of	environmental	risk	assessment	acknowledges	that	soil-	and	site-specific	factors	such	as	clay	mineralogy,	soil	conservation	practices,	and	landscape	position	alsoinfluence	P	loss	(Osmond	et	al.,	2006;	Sharpley	et	al.,	2003).Other	Phosphorus	IndicesSoil	P	management	and	soil	chemistry	can	be	challenging	to	relate	to	the	non-scientist.	The	dualusage	of	"Phosphorus	Index"	has	potential	for	confusion.	Nevertheless,	the	term	appearsoccasionally	in	the	literature	describing	yet	other	phenomena,	such	as	soil-bound	P	sorption-desorption	release	to	water	(e.g.,	Hooda	et	al.,	2000).SummaryPhosphorus	management	has	important	implications	for	agriculture	and	environmentalstewardship.	The	term	"Phosphorus	Index"	has	multiple	uses,	and	Extension	nutrient	managementprogramming	must	be	specific.	With	widespread	adoption	of	the	environmental	risk	assessmentPhosphorus	Index,	Extension	soil	testing	programs	should	use	the	term	"category"	rather	thanindex	to	quantify	or	describe	soil	test	levels.ReferencesBeegle,	D.	B.	(2005)	Assessing	soil	phosphorus	for	crop	production	by	soil	testing.	In:	J.T.	Sims	&A.N.	Sharpley	(eds.)	Phosphorus:	Agriculture	and	the	environment.	Agronomy	Monograph	46.American	Society	of	Agronomy,	Inc.,	Madison,	WI.Carpenter,	S.	R.,	Caraco,	N.	F.,	Correll,	D.	L.,	Howarth,	R.	W.,	Sharpley,	A.	N.	&	Smith,	V.	H.	(1998)Nonpoint	pollution	of	surface	waters	with	phosphorus	and	nitrogen.	Ecological	Applications8(3):559-568.Hansen,	N.	C.,	Lemunyon,	J.	L.,	Sharpley,	A.	N.,	&	Daniel,	T.	C.	(2002)	The	fate	and	transport	ofphosphorus	in	agricultural	systems.	Journal	of	Soil	and	Water	Conservation	57(6):408-417.Hooda,	P.	S.,	Rendell,	A.	R.,	Edwards,	A.	C.,	Withers,	P.	J.	A.,	Aitken,	M.	N.,	&	Truesdale,	V.	W.(2000)	Relating	soil	phosphorus	indices	to	potential	phosphorus	release	to	water.	Journal	ofEnvironmental	Quality	29(4):1166-1171.Fixen,	P.	E.,	&	Grove,	J.	H.	(1990).	Testing	soils	for	phosphorus.	Pp.	141-	180.	In:	R.L.	Westerman(ed.)	Soil	testing	and	plant	analysis.	3rd	Edition.	Soil	Science	Society	America	Book	Number	3.Madison,	Wisconsin.Lemunyon,	J.	L.,	&	Daniel,	T.	C.	(2002)	Quantifying	phosphorus	losses	from	the	agricultural	system.Journal	of	Soil	and	Water	Conservation	57(6):399-401.Natural	Resources	Conservation	Service	(NRCS).	(1999).	General	manual,	190-GM,	Issue	9,	Part402.	Retrieved	March	27,	2006	from:	http://www.nrcs.usda.gov/technical/ECS/nutrient/gm-190.html.Osmond,	D.	L.,	Cabrera,	M.	L.,	Feagley,	S.	E.	Hardee,	G.	E.,	Mitchell,	C.	C.,	Moore,	Jr.,	P.	A.,Mylavarapu,	R.	S.,	Oldham,	J.	L.,	Stevens,	J.	C.,	Thom,	W.	O.,	Walker,	F.	R.,	&	Zhang,	H.	(2006)Comparing	southern	phosphorus	indices.	(in	review	Journal	of	Soil	and	Water	Conservation).Peck,	T.	R.,	&	Soltanpour,	P.	N.	(1990)	The	principles	of	soil	testing.	Pp.	1-10.	In:	.L.	Westerman(ed.)	Soil	testing	and	plant	analysis.	3rd	Edition.	Soil	Science	Society	America	Book	Number	3.Madison,	Wisconsin.Sharpley,	A.	N.,	Weld,	J.	L.,	Beegle,	D.	B.,	Kleinman,	P.	J.	A.,	Gburek,	W.	J.,	Moore,	P.	A.,	&	Mullins,	G.(2003)	Development	of	phosphorus	indices	for	nutrient	management	planning	strategies	in	theUnited	States.	Journal	of	Soil	and	Water	Conservation	58(3):137-151.Copyright	©	by	Extension	Journal,	Inc.	ISSN	1077-5315.	Articles	appearing	in	the	Journal	become	the	property	of	theJournal.	 Single	 copies	 of	 articles	 may	 be	 reproduced	 in	 electronic	 or	 print	 form	 for	 use	 in	 educational	 or	 trainingactivities.	Inclusion	of	articles	in	other	publications,	electronic	sources,	or	systematic	large-scale	distribution	may	bedone	only	with	prior	electronic	or	written	permission	of	the	Journal	Editorial	Office,	joe-ed@joe.org.If	you	have	difficulties	viewing	or	printing	this	page,	please	contact	JOE	Technical	Support©	Copyright	by	Extension	Journal,	Inc.	ISSN	1077-5315.	Copyright	Policy

Understanding the Different Phosphorus Indices in Nutrient Management Planning

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Understanding the Different Phosphorus Indices in Nutrient Management Planning

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