2011_Starter_Fertilizer_Canada_HQ.pdf

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Starter Fertilizer in Corn ProductionStarter ertilizer in corn production has traditionally been

recommended or elds with low phosphorus (P) levels or coolsoil temperatures due to early planting, high residue cover ornorthern location. In those conditions, starter ertilizer placednear the developing seed provides easily accessible nutri-ents until soil conditions improve and a larger root system isestablished. However, some growers seeking to exploit current

grain price opportunities are evaluating whether starter canplay a more prominent role in increasing corn yields.

Starter Fertilizer Defned

Starter ertilizer is dened as small amounts o plant nutri-ents nitrogen (N), phosphorus (P) and potassium (K) placedin close proximity to the seed, usually at planting (Hergert andWortmann, 2006). To be considered starter, nutrients must bestrategically positioned to enhance early seedling vigor and de-velopment directly below the seed, to the side or both.

Starter ertilizer placed in contact with the seed (pop-upertilizer) is another option, but its use requires a great deal o

caution to avoid possible germination and seedling injury. Theamount o pop-up that can saely be applied is limited, and de-pends on the ertilizer used and soil properties. For example,starter ertilizer containing ammonium thiosulate should not beplaced in contact with the seed (Hergert and Wortmann, 2006).

A starter ertilizer is usually composed o two or morenutrients. Under most situations, a combination o nitrogenand phosphorus constitutes an eective starter material. Liquid10-34-0 and dry 18-46-0 are common starter ertilizer materials.Liquid 7-21-7 and dry 8-32-16 are also commonly used. Additiono zinc and/or sulur may be warranted in sandy, low organicmatter soils, and other materials may also be used.

Early Corn Root DevelopmentAter corn seeds imbibe enough water or germination,

the rst root structure to emerge is the radical, which is soon

ollowed by the lateral seminal roots (Figure 1).

Radicle

Seminal Roots

Nodal RootsColeoptile

Mesocotyl

First Leaf

Second Leaf

(V2 Growth Stage)

Figure 1.Early

plant

structures

o corn.

The seminal root system does not take up substantial quan-tities o nutrients; instead, the young seedling relies primar-ily on the stored nutrient reserves o the seed at this stage o

Figure 2. Case IH and John Deere tractors equipped with tanks orliquid starter application at planting.

Stresses May Impede Nodal Roots

Stresses that impede nodal root development may becontinuous in the eld, or may occur sporadically (variably) inmicro-environments throughout the eld. Sporadic stressesinclude: uneven residue distribution, dry or cloddy soils, wetspots, diagonal anhydrous ammonia bands, ertilizer salt injury,

wheel trac compaction, seed urrow (sidewall) compaction,insect or herbicide damage to roots, and soilborne diseases.

Sporadic stresses can have their air share o detrimentalconsequences to grain yield. This is because individually a-ected plants are likely to all behind i conditions remain una-vorable. Once a plant alls behind by two or more physiologicalgrowth stages, it will be shaded and outcompeted by it neighborsand will likely not catch up, resulting in uneven stands (Figure 3).

Figure 3. Uneven stand due to wet soil conditions. Note that variablesoil areas are aecting some plants more than others.

Uneven stands have been reported to suer corn grainyield reductions rom six to as much as 23 percent dependingon the severity (Nielsen, 2010; Naziger, et al., 1991). This yield

loss could be signicantly reduced by starter ertilizer applica-tions in cases where the primary cause o uneven stands is theinability o the young nodal root system to access sucient soilnutrients.

Research on Corn Yield Response to Starter

Starter ertilizer applications to corn have been wellresearched and documented. The scientic literature showsnumerous cases where starter has produced positive, meagerand no corn grain yield increases. This array o results meansthat positive grain yield responses are likely related to bothenvironmental and cultural interactions. Starter research

development. Soon ater emergence (VE) the young corn seed-ling will begin to develop its nodal root system, the primary rootsor water and nutrient uptake o the plant.


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across geographies has generally shown that areas o the

northern Corn Belt more consistently and positively respond to

starter ertilizer. In the central Corn Belt, elds managed with

notill or reduced tillage, poorly drained elds, or those testing

low in P were more likely to respond.

Consistent grain yield responses to starter ertilizers may

also be expected on soils that have low soil organic matter

or soils that have coarse (sandy) soil surace textures. Many

soils ormed rom Mississippi River alluvium that stretch rom

portions o central Minnesota to the Gul o Mexico t thisdescription. Average grain yield responses o 12.5 bu/acre were

documented in some studies on these soils (Mascagni et al.,

2007). In these studies (Figure 4), the largest and most consis-

tent yield responses were on the sandiest soils, and grain yield

responses were more likely rom the P in the starter.

Figure 4. Infuence o starter ertilizer on corn yield on Mississippi Riveralluvial sandy loam/silt soils at the NE Research Station at St. Joseph,

Louisiana. Mascagni et al., 2007. NS = Non-signicant at the .05 prob-

ability level.

75

90

105

120

135

150

165

180

195

210

225

1991

1992

1993

1995

1996

1996

1997

1997

1998

1999

2000

2001

2002

2003

2005

No Starter

Starter

Corn

GrainYield(

bu/acre)

NS

NS

NS

NS

NS

NS

NS

NS

NSNS

Hybrid Responses to Starter Fertilizer

A Kansas State study with ve hybrids in a notill system

ound that starter ertilizer (N and P) signicantly increased early

season growth, N and P uptake at V6, and N and P concentra-

tion in the ear lea (Gordon, et al.. 1997). All hybrids responded

similarly to the starter application. The study also ound that all

hybrids required less growing degree units (GDUs) to pollination

when starter was used, with an average o 80 less GDUs required.

This is a key nding or dryland corn production in Kansas,

where yield is oten limited by late season drought stress.

Banded Applications More EfcientApplication o P as a starter ertilizer is usually more ecient

than broadcast applications, especially when inherent soil P

levels are very low or or calcareous high pH soils above 7.5

(Shapiro et al, 2003). For example, recommended P rates can

be reduced by 1/2 when applied as a banded starter ertilizer

compared to broadcast application (Table 1). This is because

banded starter applications result in less soil immobilization

and more crop available P than broadcast applications, espe-

cially or high pH soils with low P levels. Use o a band-applied

P starter is an especially appealing alternative to broadcast ap-

plication when P based ertilizers are extremely expensive.

Table 1. P ertilizer recommendations (Shapiro, et al, 2003).

Soil P Level (ppm P)Relative

LevelAmount o P toApply (P

2O

5)1

Sodium Bicarbonate Broadcast Band

0 - 3 Very Low 110 40

4 - 10 Low (100-50) (50-25)

11 - 16 Medium N/A 20

1 Data supplied by Ontario Agronomy Guide or Field Crops Pub 811

Avoiding Salt Injury rom Starter Fertilizers

The rate at which a starter ertilizer can be applied depends

on the salt content or index o the ertilizer, proximity o starter

to the seed, and soil texture (Hergert and Wortmann, 2006). Salt

index is a unction o the sum o the N, P and S content in the

ertilizer (Table 2, Mortvedt, J.J. Calculating Salt Index).

Table 2. Salt index comparisons or commonly used starters, expressedas pounds o salt eect/gal and relative to 10-34-0.

Product AnalysisSalt Index,

lb/gal

ValueRelative to

10-34-0

Ammonium

polyphosphate10-34-0 2.28 1

7-21-7 7-21-7 3.04 1.33

Urea ammonium

nitrate28-0-0 6.75 2.96

Urea ammonium

nitrate32-0-0 7.78 3.41

Ammonium thiosulate 12-0-0-26 30.9 13.55

The limits or application rates o 10-34-0 to help avoid salt

injury as a unction o ertilizer placement and soil texture are

shown in Table 3.

Table 3. Gallons o 10-34-0 4 that can be saely applied or corn2 in 30-inch rows3 as infuenced by distance rom the seed and soil texture

(Hergert and Wortmann, 2006.)

PlacementSandySoils

Non-SandySoils

10-34-0 (gal/acre)1

With the seed (pop-up) 5 5

1/4 to 1/2 inch rom the seed 10 10

1 inch rom the seed 20 40

2 inches or more rom seed 20+ 40+

1 Determine sae application rates or other ertilizers by dividing thevalue in Table 3 by the Value Relative to 10-34-0 in Table 2.

2 The sae application rate or soybeans is 1/2 o these values.3 For row-widths narrower than 30 inches, the application rate may be

increased. Multiply values by 1.5 or 20-inch rows, 1.36 or 22-inchrows, and 2.0 or 15-inch rows.


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Salt damage is most pronounced when soil moisture is

low, so adequate soil moisture at planting or rainall soon ater

help minimize salt injury. To diminish the probability o salt in-

jury, avoid over-applying nitrogen, potassium or sulur ertilizers

close to the seed.

Corn grain yield increases from starter fertilizer

applications are most likely: In northern portions o the Corn Belt, regardless o

tillage practices

Whenculturalpracticessuchasno-tillorminimum

tillage are utilized

Oncoarsetexturedandorloworganicmattersoils

Onpoorlydrainedorcoldsoils

OnlowtestingPandKsoils

Whennodalrootsystemsareseverallyimpededby

stresses

WhensoilspHisunusuallyhighorlow

Whensubstantialdroughtstressislikely

Higher corn prices and changes in arming practices (e.g.,

earlier planting) may create new roles or starter ertilizers

beyond their traditional applications. One such role may be as

insurance against prolonged, unavorable weather conditions

occurring soon ater planting. Growers and agronomists are en-

couraged to continue testing starter ertilizer in a variety o eld

situations to urther determine when and where these treat-

ments may be most responsive.

Reerences

Gordon, W. B., D.L. Fjell, and D.A. Whitney. 1997. Corn hy-

brid response to starter ertilizer in a no-tillage, dryland environ-

ment. J. Prod. Agric. 10:401404.

Hergert, G.W. and C.S. Wortmann. 2006. Using starter er-

tilizers or corn, grain sorghum and soybeans. NebGuide G361.

Univ. o Nebraska Coop. Ext. Service, Lincoln.

Mascagni, H.J., B.B. Boquet. 2007. Infuence o starter er-

tilizer on corn yield and plant development on Mississippi River

alluvial soils. Better Crops. Vol. 91.2.

Mortvedt, J.J. Calculating salt index. Spectrum Analyticwebsite. (Veried 12/15/2011). http://www.spectrumanalytic.

com/support/library//salt_index_calculation.htm

Naziger, E.D., P.R. Carter, E.E Graham. 1991. Response o

corn to uneven emergence. Crop Sci. 31: 811815.

Nielsen, R.L. 2010. The emergence process in corn. Corny

News Network, Purdue Univ. (On-Line).

Shapiro, C.A., R.B. Ferguson, G.W. Hergert, A. Dobermann,

and C.S. Wortmann. 2003. Fertilizer suggestions or corn. Neb-

Guide G74-174-A. Univ. o Nebraska Coop. Ext. Service, Lincoln.

Conclusions

, SM, TM Trademarks and service marks o Pioneer Hi-Bred. 2011 PHII

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2011_Starter_Fertilizer_Canada_HQ.pdf