Double-CroppedWinter Forages

By Bradford Brown and Thomas Griggs

BUL 869

TABLE OF CONTENTS

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .page 2

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .page 2

Dry Matter Production and P Removal . . . . . . . . . . . . .page 3

Winter Forage Seeding Rates . . . . . . . . . . . . . . . . . . . . . .page 5

Triticale Phosphorus Concentrations and Removal . . .page 5

Nitrogen Management for Winter Forage . . . . . . . . . . .page 8

Planting Dates for Winter Forage . . . . . . . . . . . . . . . . .page 10

No-Till Planting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .page 11

Growth Stage and P Uptake . . . . . . . . . . . . . . . . . . . . . .page 11

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .page 12

Additional Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . .page 12

SUMMARY

• Double cropping winter forages with corn silageincreases total forage available to dairy and otherlivestock operations while increasing total crop phos-phorus (P) removal.

• To maximize forage production and/or P removal,plant early; use higher seeding rates than are neces-sary for grain production; and use a preplant nitrogen(N) fertilizer.

• Triticale produces more dry forage and removes moreP than wheat or barley.

• The maximum rate of P uptake by winter foragesoccurs during late vegetative growth.

• Triticale boot-stage forage P concentrations variedwidely depending on soil P enrichment, so accurateestimates of P removal require measuring both dryforage production and its P concentration.

• Since Idaho growing seasons tend to be short, directseeding may facilitate timely replanting andmaximum heat unit utilization.

• Boot-stage triticale forage protein can provide areasonable indication of the adequacy of N for forageproduction.

INTRODUCTION

Due to water quality concerns, Idaho confined animalfeeding operations (CAFOS) such as dairies are requiredto manage animal wastes as never before. Phosphorus(P) is the nutrient of greatest concern since it is thenutrient most responsible for nuisance aquatic growthsuch as algae.

Current Idaho rules have established a soil test phos-phorus (STP) threshold of 40 ppm (bicarbonateextraction) in the first foot in fields where there ispotential for runoff. Above this threshold additionalmanure applications to the soil are limited to theamount of P removed by crops.

Some dairies have limited land resources and moremanure P than can possibly be removed with annualcropping. Once the P threshold is reached, compliancerequires dairies to (1) reduce the P loading by reducing

the manure generated, possibly limiting their milkproduction or herd size for the limited acreage; (2)increase land resources available for manure applicationthrough purchase or arrangement with other landowners, or extending delivery systems to previouslynon-manured fields; or (3) increase crop P removal.

Increasing the amount of P removed in harvested cropsis helpful in mitigating the effects of P applied inmanures and composts. Greater crop P removal slowsthe rate at which STP increases or helps reduce STP overtime; reduces the need for capital improvementsrequired for extending manure delivery systems; enablesdairy herd expansion; or increases soil P loading capacity.

Double-crop (winter cereal and corn) forage systemsappreciably increase the P removed over that removedwith a single corn silage crop, and increase total foragefor the dairy enterprise. Ideally, winter cerealsharvested at the late vegetative or boot stage beforeheading (rather than soft dough near the end of grainfill) provide additional quality forage and increase Premoval without sacrificing silage corn production.

A later dough-stage winter cereal forage harvest insouthern Idaho precludes growing corn because theremaining growing season is too short. Furthermore,winter cereals do not take up much more P afterheading (although they do produce more totalbiomass). Thus, a boot-stage harvest does not sacrificeP removal nearly as much as it does biomass.

Winter cereal forages in Idaho historically were removedat the dough stage. Dough stage forages are stillproduced, but the more predominant use of winter cerealforages currently is a late vegetative, boot-stage forageharvest to accommodate a more timely planting of corn,the summer crop of the double-cropping system. Sincepertinent information on boot-stage winter cerealproduction and P removal as a component of the double-crop system in southern Idaho has not been summarized,that information is the focus of this bulletin.

Double cropping would not involve additional equip-ment for most enterprises already producing swathedand chopped forages. Double cropping would entailadditional labor and operating costs.

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Figure 1. Annual and cumulative winter forage dry matter produc-tion when harvested at the boot stage

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Total winter forage production over three years ranged from 6.5 to8.8 tons of dry matter per acre (figure 1). Winter triticale averagedthe highest in total forage production over the three years. Winterwheat and barley were less productive than triticale over three years,but more productive than fall-planted spring wheat. Winterkill re-duced winter barley and fall-planted spring wheat stands in the firstyear of the three-year study, reducing production in that year andthe cumulative total production over the three years. With no win-terkill, annual forage production among fall-planted forages did notdiffer significantly.

Winter forage P removal over three years ranged from 36 lb per acrefor fall-planted spring wheat, to 58 lb per acre for winter triticale(figure 2). Phosphorus removal basically mirrored forage production.However, minor differences in winter forage P concentrations tendedto magnify the differences between some forages. For example,spring wheat averaged 75% of the forage production of winter triti-cale, but only 62% of the P removal. Consequently, forages differedmore in P removal than they did in dry matter production.

Forage dry matter production, and especially P removal, appeared todecline with each season in winter forages unaffected by winterkill(figures 1 and 2). This was likely due to declining available soil P. Win-ter forage average P concentrations declined from 0.39% in the firstseason to 0.25% in the third season (data not shown). Soil test P alsodeclined over the three years of double cropping to about 12 ppm.

Irrigation requirements would increasesomewhat: for winter forage establish-ment possibly, but primarily to supportspring vegetative growth. Winter foragesin most dairies in the region are irrigatedwith storage lagoon water so they provideadditional opportunity for emptyinglagoons. Annual N requirements wouldincrease for this double crop system.

While double cropping is an excellent wayto maximize forage and P removal, winterforages may not fit into all dairy or beefenterprises. Furthermore, winter foragefeed quality, which declines as winterforage approaches heading and floweringgrowth stages, can be an issue if theharvest is delayed by weather.

DRY MATTER PRODUCTION ANDP REMOVAL

Several winter cereals have been evalu-ated for their capacity to accumulate P bythe boot stage in a double-crop foragesystem. A three-year study was con-ducted at the Parma Research and Exten-sion Center (elevation 2300 ft) insouthwestern Idaho involving three wintercereals (barley, wheat, and triticale) andtwo spring cereals (wheat and triticale), allfall planted at three seeding rates (100,150, or 200 lb/A).

Planting dates for winter forages were Oc-tober 21, 1998, September 27, 1999, andOctober 3, 2000. Boot-stage harvestswere May 20, 1999, April 27, 2000, andMay 11, 2001. Two non-planted fall treat-ments were also included: one used for theproduction of a single crop of silage corn,and the other kept fallow for the durationof the study. Treatments were repeatedevery year in the same plot so that cumu-lative effects of treatments on soil test Pafter three years could be determined.

Fields with soil test P considerably abovethe values in this trial would likely result inhigher forage P concentrations, and possi-bly greater forage yield and P removal.While the highest soil test P measured inthe first year of our study was 31 ppm, soiltest P can range up to several hundredppm in manured fields.

Following winter forages, cumulative cornsilage yield over the three years rangedfrom 5 to 16% less than corn alone. Lowercorn yields following winter forage wereprimarily due to poorer stands from no-tillplantings and regrowth of triticale in thefirst year. Total forage yield (winter forageand corn silage) ranged from 31 dry tonsper acre with corn alone, to 36 dry tons peracre with double-cropped spring wheat andcorn (figure 3).

Corn silage P removal ranged from 105 to119 lb per acre over the three years, con-siderably more than removed with thewinter forage (figure 4). Average silagecorn P removal was not affected over thethree years by previous winter forages, assilage corn yield may have been. Interest-ingly, winter forage/silage corn combina-tions that resulted in the highest Premoval did not always result in the great-est total double-crop forage.

The combined P removal with winter for-age/corn silage double cropping rangedfrom a high of 168 lb P per acre with win-ter triticale and corn, to a low of 154 lb Pper acre with spring wheat and corn. Corngrown alone (not as part of a double-crop-ping system) removed only 120 lb P peracre. Silage corn grown in areas withlonger growing seasons likely has greaterpotential for yield and P removal than in-dicated here.

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Winter Forage

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Figure 3. Annual and cumulative winter forage and silage corn drymatter (DM) yield

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Figure 2. Annual and cumulative winter forage P removal whenharvested at the boot stage

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Winter Forage

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Figure 4. Annual and cumulative winter forage and silage corn Premoval

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Figure 5. Winter forage boot stage dry matter as affected by win-ter forages and seeding rates

WINTER FORAGE SEEDINGRATES

Seeding rates exceeding 100 lb/A seldomincrease grain yield of early planted wintercereals, in part because many tillers areproduced that never produce a grain-bear-ing head. While non-bearing tillers maynot contribute significantly to grain yield,they can contribute to boot-stage forageproduction and P removal. Since seedingrates appropriate for boot-stage harvestedforage were not well established, the win-ter forages at Parma were evaluated atthree seeding rates (100, 150, and 200 lbseed per acre).

Seeding rates of 150 lb/A were requiredfor maximum production in all years forwinter triticale, spring triticale, and winterwheat forages (figure 5). Spring wheatand winter barley dry matter productionwere less sensitive to seeding rates. Phos-phorus removal was not as sensitive toseeding rate as was dry matter production.Only in winter triticale and winter wheatwere seeding rates of 150 lb per acre nec-essary for maximum P removal (figure 6).Spring triticale and spring wheat P re-moval were less sensitive than the wintertypes to seeding rates over the three-yearperiod. Seeding rates of 200 lb/A for win-ter wheat and triticale provided little ifany advantage in productivity or P re-moval over the 150 lb/A rate.

TRITICALE PHOSPHORUS CONCENTRATIONS AND REMOVAL

It is important to test the P in crops usedto remove P from the soil, in order to moreaccurately document the P removed, andhow much P is fed in the animal’s ration.An estimated average value of P removalmay not at all reflect how much P is inyour particular crop.

For example, the Idaho OnePlan softwareuses an estimate of triticale P concentra-tion based on the National ResearchCouncil (NRC) value of 0.34% P forheading triticale ensiled. Since triticale Pconcentrations from southern Idahomanured fields were poorly documented, asurvey was conducted of 44 manuredfields in the Magic and Treasure Valleysduring spring 2004 and 2005 to establishan Idaho baseline. We found considerablevariation in P concentrations of the triti-cale grown.

Triticale total P concentration rangedwidely from 0.18 to 0.53% P, with a meanof 0.33% for boot-stage samples (figure7). This mean value is practically the sameas the NRC mean value of 0.34% for triti-cale at heading (after ensiling). However,there was a wide variation in P concentra-tions. In figure 7 the mean is bracketed bylines representing P concentrationsdiffering by 10% from the mean. Forage Pin most samples falls outside the range of0.30-0. 36% P. Over three-quarters of thefields were either above (43%) or below(34%) the 10% bracket on each side of themean. Using a mean value for triticale Pconcentration for calculating P removalwith triticale would grossly underestimateP removal in some fields and overestimateP removal in others. The range neverthe-less suggests considerable potential foraccumulating P quantities above thoserequired for growth.

Tissue P concentrations can be dilutedwith greater dry matter production, andhigher concentrations may occur when drymatter production is limited by factorsother than available P. In other words,when growth is abundant, individualplants may have a lower P concentrationthan when growth is more limited.

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Winter Forage

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Figure 6. Winter forage boot stage P uptake as affected by winterforages and seeding rates

Figure 7. Winter triticale boot stage forage P concentrations forsouthern Idaho manured fields

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Figure 8. Triticale boot stage forage P concentrations in southernIdaho. (Large symbols are outliers that are not included in the re-gression.)

Western Idaho triticale dry biomassranged from 1.58 to 5.95 tons/A in 2004,and 2.95 to 3.81 in 2005. The P removedranged from 7 to over 36 lb/A in 2004,and from 13 to 34 lb/A in 2005. Triticaleforage P removal exceeding 30 lb/A isconsiderably more than that documentedin research trials to date involving non-manured soils. Biomass and P removalranged every bit as much as P concentra-tions. Total P concentrations and drymatter production both should be meas-ured for the most accurate estimates of Premoval.

Using NRC estimates of P removal hassignificant implications. Overestimating Premoval can lead to higher manuring ratesthat steadily increase soil test P values.The opposite occurs when NRC valuesunderestimate P removal and manuringrates or estimates are lower than thoseallowed by the statute. In the latter case,soil test P would decline more rapidly asmore P is actually removed than is appliedwith manure. Underestimating P removalcould cause you to overestimate the landsrequired to accommodate your CAFO.Higher estimated land requirementsunnecessarily increase the costs for devel-opment or expansion of an operation, orthe estimated amount of manure thatshould be exported, leading to unneces-sary hauling and application costs.

Using more accurate (measured yield andforage analysis based) P removal esti-mates also has significant implications forforage N fertilization. If your crops areremoving more P than the book value,then you will be able to apply moremanure to the land, and thus will need tobuy less N fertilizer. Conversely, if less Premoval occurs than the book value,manuring rates may be reduced and morefertilizer N may be needed.

Knowing actual triticale forage P concentrations may also be usefulfor adjusting P in the ration. Feeding forages with a higher P concen-tration can reduce the need for P supplementation. Reducing ration Pconcentrations will reduce P content of manures. This in turn enableshigher manuring rates and reduced dependence on purchased fertil-izer N.

When there are no forage P analyses to use for estimating P removal,as when a nutrient management plan is first developed for an old ornew dairy or feedlot, there may be a better estimate of triticale Pconcentration than using the NRC book value of 0.34% P. There maybe soil test P information available even if there is no history of triti-cale production and the related forage P analysis. In this survey,triticale P concentrations increased and then stabilized as soil test Pincreased (figure 8).

For older animal enterprises with fields that show high soil P (above150 ppm), a more appropriate default value would be 0.40% P.Conversely, in fields with low to moderate soil test P (below 40 ppmP), as perhaps with new CAFOs, a more appropriate initial defaultvalue for boot stage triticale P concentration might be 0.30%. Whilethe soil-test-based estimates of triticale P concentration may beuseful for initial planning, they should not substitute for P analysesof actual triticale harvested.

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Other chemical elements in the foragealso range widely. For example, potassium(K) in forage triticale ranged from 1.97 to6.17%, and averaged 3.71%. Forage triti-cale K was high enough in some locationsto be of concern, since excessive forage Kcan suppress magnesium uptake, leadingto milk fever. Copper (Cu) in triticalediffered by as much as tenfold. Elevatedforage Cu may reflect contributions fromfoot baths. Likewise, forage zinc (Zn)concentrations ranged from 12.7 to 102ppm. Zinc levels of less than 20 ppmcould limit boot-stage forage production.Sodium (Na) concentrations in triticalevaried the most of all minerals, rangingfrom 146 to 7552 ppm. Forage Na likelyreflects both the history of manuring aswell as the amount of sodium salts used inthe ration.

NITROGEN MANAGEMENT FORWINTER FORAGE

A phosphorus-based manuring standardreduces manuring rates compared to anitrogen-based standard, and ultimatelyrequires the purchase of fertilizer N tomaintain or maximize forage production.This occurs because the N:P ratio ofmanure, especially if composted, is lowerthan the N:P ratio of harvested forage.

Whereas the N and P requirements formaximizing the grain yield of irrigatedsmall grains or corn silage are reasonablywell established, the N requirements forboot-stage triticale forage are not. Forgrain production, late winter/early springtopdressed N is frequently more effectivethan fall preplant fertilizer N. Fall preplantfertilizer N reportedly increases vegetativegrowth without increasing grain yield andis discouraged by NRCS 590 standardsgoverning waste applications.

Whereas excessive vegetative growth for the production of wheatgrain is undesirable, it is beneficial for boot-stage forage harvest, Premoval and P remediation. Phosphorus uptake and forage P concen-trations are reported to be directly related to available N.

To evaluate N timing and rate for triticale boot-stage forage produc-tion, quality, and P content, a study was conducted on plotspreviously treated with or without compost that resulted in margin-ally low to relatively high available P.

Triticale boot-stage forage was generally more productive with fallpreplant N than spring topdressed N (figure 9a). Phosphorus uptakealso tended to be higher with the preplant N timing (figure 9b).

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Figure 10. Boot stage triticale P uptake. (Uptake of P is averagedacross both years and N timing.)

Figure 11. Boot stage triticale relative forage yield (percent of maxi-mum) as related to forage protein concentration.

Uptake of P was higher with previous compost applied (figure 10) andthe increase with N was greatest in compost-treated, higher P soil.Uptake of P appears to be more sensitive than forage yield to availableN in soils enriched with P.

The optimum rate of N fertilization may be difficult to predict. In ourstudy, the optimum preplant N turned out to be 120 lb per acre in2006, but only 60 lb per acre in 2007 despite lower residual N at

planting (118 lb N/A in 2005 and 76 in2006). One reason may be that thelower production in 2007 did not requireas much N. Climatic conditionsaffecting productivity likely will affectthe total N required.

High forage nitrate-N concentrations(over 1000 ppm) can be toxic to live-stock when available N appreciablyexceeds the optimum. High nitrate-Nconcentrations are not generally anissue if the forage is not drought-stressed at harvest. In our irrigatedstudy with no stress, we exceeded theoptimum rate by four times, and thenitrates in the forage still did not reachtoxic levels. For example, nitrates in theforage were higher in 2007 than 2006,yet reached only 890 ppm with thehighest preplant N rate of 300 lb N/A.Nevertheless, a nitrate analysis shouldbe included with other tests performedto determine feed quality. Nitratestended to be higher with spring topdressthan preplant N, especially at N ratesabove the optimum.

While it is difficult to recommend anoptimum level of fertilizer N, you canget a sense after the harvest as towhether your N fertilization wasadequate, by measuring the proteincontent of the forage. Protein isroutinely measured in harvested foragesto better balance livestock rations.Maximum forage production coincidedwith boot-stage forage protein rangingfrom 10.5 to 11.0% (figure 11).Therefore, if forage protein is within thisrange or higher, the N fertilizationprovided was likely adequate.

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Figure 13. Mean winter forage re-growth after simulated late fallgrazing at Logan, UT in 2003

Figure 12. Wheat winter forage dry matter as affected by fallplanting date and spring sampling at Parma, ID, 1983

PLANTING DATES FOR WINTERFORAGE

Early planting dates for winter forages(mid September to early October in theTreasure Valley, early to mid September inthe Magic Valley) are critical for maxi-mizing boot-stage forage production. Thelonger it takes winter forages to reach theboot stage, the more delayed the boot-stage harvest, and the more the growingseason for corn is reduced. Shortenedgrowing seasons for corn necessitate usingshorter season and less productivehybrids. Alternatively, harvesting earlierthan boot stage sacrifices winter foragedry matter production and P removal.

To illustrate planting date influence,Stephens winter wheat was plantedSeptember 30, October 16, and November2, 1983 at Parma, ID. Forage dry matter attwo harvest dates are shown for each ofthe planting dates in figure 12. On theMay 11 harvest, wheat planted October 16was only 52% as productive as theSeptember 30 planting, and theNovember 2 planting only 28% as produc-tive. Whereas the September 30 plantinghad reached the boot stage with flagleaves fully emerged, the later plantingswere at earlier stages of development.

Forage dry tonnage increased by the nextharvest on May 24, and increases weregreatest in the later plantings. By the May24 harvest, later plantings had partiallycaught up with the first planting in drytons produced. Even so, the November 2planting was only 52% as productive asthe September 30 planting. Corn plantedsubsequent to a May 24 winter forageharvest would be a relatively late plantingof corn for western Idaho, and typicallyless productive if a shorter season hybridwere required.

Concentrations of P were not measured in these wheat forages.Assuming P concentrations are similar to those measured in otherwheat forage studies with comparable available P, we assume forageP of 0.25%. Using this P concentration , the total winter forage Puptake for the September 30, October 16 and November 2 plantingswould be 15.5, 8.2, and 5.7 lb P per acre respectively. Earlier plantingdates result in more P uptake.

Planting dates of winter forages at higher elevationswere also shown to drastically affect both fall grazingpotential and spring forage regrowth productivity. AtLogan, UT (elevation 4598 ft), planting dates in 2001and 2002 ranging from August 22 to October 11 wereevaluated to determine fall and spring productivity ofseveral cultivars of barley, triticale, and wheat. Foragedry matter production per acre by the mid-Novemberharvest decreased 47 to 62 lb per day as planting dateswere delayed from the first planting date (either August22, 2001 or August 27, 2002). Forage mass of regrowththe following spring (April) decreased by 37 to 76 lb perday depending on the cultivar. The average forageregrowth at two spring cuttings of all winter forages atLogan are shown in figure 13.

Optimum winter forage planting dates, within thecontext of double-cropping with corn, will varydepending on elevation and the length of the frost-freegrowing season for corn. Winter forage planting dateswill be later and the spring harvest earlier in milderclimates, providing additional frost-free days for usinglonger-season and more productive corn hybrids. If cornsilage production is paramount, planting dates forwinter forages will frequently be later than optimal, asproducers will be reluctant to sacrifice silage yield byusing shorter-season corn hybrids.

While producers don’t always have control over thetimeliness of planting winter forages, planting dates haveconsiderable influence on forage quantity and P removal.

NO-TILL PLANTING

The time required to plant corn after harvesting winterforage, or to plant winter forages after harvesting cornsilage, can stretch to several days or weeks dependingon available labor, equipment, and weather conditions.Preparing new seed beds for planting subsequent cropscan make it even harder to plant at optimal times. Aswe have shown above, planting delays can significantlyaffect winter forage productivity.

No-till or strip-till seedings can facilitate more timelyplantings. While no-till and strip-tillage are notcommonly used by most irrigated producers, they areused by a few. There is typically little residue associatedwith planting winter forage into harvested silage corn, orcorn into winter forage stubble. However, using conven-

tional double disk openers for planting corn into the shortwinter forage stubble can be problematic without sometillage to soften the ground and uproot the live crowns.

Even where corn is successfully established with no-tillplantings following triticale removal, triticale regrowthin the corn row especially was problematic and appre-ciably reduced corn vigor. Regrowth of wheat and barleywas not as much of a problem for corn as with triticale.Using herbicides to control triticale regrowth may bepossible, but those applications depending on leaf inter-ception can be problematic, since there is little leafsurface immediately after the winter forage harvest.

Strip tillage is therefore recommended over no-till,because it reduces the competition from triticale regrowth.

GROWTH STAGE AND P UPTAKE

Generally, deciding when to harvest the winter forage isdictated by the onset of the corn growing season.Regardless of the growth stage of the winter forage,producers are apt to sacrifice winter forage productionand P removal in favor of a more timely and productivecorn planting.

Triticale P uptake is most rapid from mid-stem exten-sion to flowering. Uptake of P from compost andnon-compost treated soil at Parma was measured in2005 and 2006 in fall-planted triticale (figure 14). Incompost treated soil, triticale P uptake increased 7 lbP/A over 7 days in 2006 and 11 lb P/A over 10 days in2005 for an average daily P uptake of 1 lb P per dayfrom mid-stem extension to the boot stage. From theboot stage to flowering, daily P uptake slowed to about60% of the earlier rate. The daily uptake of P was about50% less for the untreated low P soil. Uptake of P wasgreatest each year from the compost treated soil due tomuch higher available soil P. For soils with soil test Pwell above the 40 ppm threshold, the higher P uptakerate can be expected.

The dry forage increase from mid-stem extension toflowering in the compost treated soil was 2.92 tons/Aover 24 days in 2005 and 2.19 tons/A over 17 days in2006 for an average daily increase of 0.125 tons/day.This study also revealed that boot stage forage wasmore limited by moderate to low soil P than was theyield of grain (data not shown).

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REFERENCES

Brown, B. D. 2006. Winter cereal/corndouble crop forage production and Premoval. Soil Science Society of Amer-ica Journal 70:1951-1956. Available at:http://soil.scijournals.org/cgi/con-tent/full/70/6/1951

Brown, Brad, Joe Dalton, Mireille Chahine,Bill Hazen, Scott Jensen and StephanieEtter. 2006. Southern Idaho WinterTriticale Forage P in Manured Fields. InEllsworth, J. (ed) 2006 Idaho NutrientManagement Conference Proceedings.Twin Falls, ID. March 7, 2006. pp 24-28. Available at:http://www.ag.uidaho.edu/SWIdaho/Cereal%20Forage/06inmcTriticalep-rocart.pdf

Brown, B.D. 2008. Triticale for PhosphorusRemoval. In Moore, A. (ed) 2008Idaho Nutrient Management Confer-ence Proceedings. Jerome, ID. March4, 2008. pp 84-89.

Brown, Bradford. 2009. Nitrogen timingfor boot stage triticale forage yieldand phosphorus Uptake. Western Nu-trient Management Conference Pro-ceedings. March 4-5, 2009, Salt LakeCity, UT. pp 62-67.

Griggs, T. C. 2006. Fall and spring forageproduction and quality of winter cere-als seeded at three fall dates. Online.Forage and Grazing Landsdoi:10.1094/FG-2006-0711-01-RS.Available at: http://www.plantman-agementnetwork.org/pub/fg/re-search/2006/date/

Figure 14. Cumulative P uptake and dry matter produced at different growth stages

ADDITIONAL RESOURCES FROM UNIVERSITY OFIDAHO EXTENSION:

Mitigating High-Phosphorus Soils: http://info.ag.uidaho.edu/pdf/BUL/BUL0851.pdf

Dairy Manure Field Applications: How Much is Too Much?http://info.ag.uidaho.edu/pdf/CIS/CIS1156.pdf

AUTHOR NOTES:

Bradford Brown is an extension soil and crop management specialistat the Parma Research and Extension Center, University of Idaho.

Thomas Griggs is a forage agronomist with the Division of Plant &Soil Sciences at West Virginia University in Morgantown.

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Issued in furtherance of cooperative extension work in agriculture and home economics, Acts of May 8 and June 30, 1914, in cooperation withthe U.S. Department of Agriculture, Charlotte V. Eberlein, Director of University of Idaho Extension, University of Idaho, Moscow, Idaho 83844.The University of Idaho provides equal opportunity in education and employment on the basis of race, color, national origin, religion, sex, sex-ual orientation, age, disability, or status as a disabled veteran or Vietnam-era veteran, as required by state and federal laws.

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