Dr. Dennis Hancock Extension Forage Specialist

Crop and Soil Sciences – UGA

Dr. Dennis Hancock Extension Forage Specialist

Crop and Soil Sciences – UGA

Fine-Tuning Fertilization in Your

Hayfields

Fine-Tuning Fertilization in Your

Hayfields

Annual Nutrient Removal by the Primary Hay Crops in the SouthAnnual Nutrient Removal by the Primary Hay Crops in the South

Nitrogen Phosphate Potash Calcium Mag0

50

100

150

200

250

300 AlfalfaBermudagrassOrchardgrassPerennial PeanutTall Fescue

Nut

rient

s Re

mov

ed(lb

s of

Nut

rient

/Acr

e/Ye

ar)

Adapted from Southern Forages, 2007 and Myer et al, 2010.

Desired Spread PatternDesired Spread PatternSpinner SpreaderAir-flow Applicator

Distribution at Various Rates

Distribution at Various Rates

Spinner SpreaderSource: Fulton et al., 2003; 2005

0

50

100

150

200

250

300

350

-18.29 -13.72 -9.14 -4.57 0.00 4.57 9.14 13.72 18.29Transverse Distance (m)

Ap

pli

cati

on

Rat

e (l

bs/

acre

)

50 lbs/A

100 lbs/A

200 lbs/A

300 lbs/A

Distribution at Various Rates

Distribution at Various Rates

Source: Fulton et al., 2003; 2005

Air-flow Applicator

-10.7 -8.0 -5.3 -2.7 0.0 2.7 5.3 8.0 10.7Spread Width (m)

Ap

pli

cati

on

Rat

e (l

bs/

acre

)

Desired Levels

400 lbs/A

100 lbs/A

200 lbs/A300 lbs/A

0

100

200

300

400

500

600

700

800

Uniform Rate SurfacesUniform Rate Surfaces

Spinner Spreader

Source: Fulton et al., 2003 and unpublished data

Air-flow Applicator

New Leader 224 kg/ha Uniform Application Surface

224 kg/ha S ingle-Pass for AgC hem

336 to 112 kg/ha Rate Transition for N ew Leader

A Rate Change….A Rate Change….

Low to High

High to Low

Source: Fulton et al., 2003

112 to 336 kg/ha Rate Transition for N ew Leader

Fertilization Trick

Account for N Loss from Urea-based Products

Account for N Loss from Urea-based Products

N Fertilizer ApplicationN Fertilizer Application

Ureaurease

+ H20

Ureaurease

Ammonia+ H20

Ammonium+Ammonium+

Ureaurease

Ammonia+ H20

Ammonium+Ammonium+

AN34-0-0

Nitrate-Nitrate-

The Effectiveness of Some Alternative N Sources at Low, Medium, and High Fertilization Rates on Hybrid Bermudagrasses (Relative to

Ammonium Nitrate).

The Effectiveness of Some Alternative N Sources at Low, Medium, and High Fertilization Rates on Hybrid Bermudagrasses (Relative to

Ammonium Nitrate).

Nitrogen Source Fertilization Rates

< 200 lbs* 250-350 lbs > 400 lbs

Ammonium Nitrate 100% 100% 100%

Amm. Sulfate 95-97% 95-105% 60-70%

Anhyd. Ammonia 92-94% 93-95% 94-95%

UAN Solution 80-85% 85-92% 92-95%

Urea 79-82% 82-92% 88-93%* Actual lbs of N per acre per year.

Source: Burton and Jackson, 1962; Silveria et al., 2007.

Alternative N SourcesAlternative N Sources

Take-home message: If you have to use a urea-based product, be

careful about cutting your rate back too much.

- They are relatively less effective at low rates.

Fertilization StrategiesFertilization StrategiesNew N Fertilizer ProductsNew N Fertilizer Products

IntroductionIntroduction• Without AN, users of

N face risky alternatives.

NH3 volatilization loss

• Urease is abundant in thatch & organic layers

High N use in hay.

• Enhanced Efficiency N Fertilizer Products may reduce volatilization loss

Urease inhibition Encapsulate &

release

Ammonium Nitrate Urea

NBPT

maleic-itaconicco-polymer

PolymerCoating

Results: Yield DataResults: Yield Data

2008-09: Forage Yield of ‘Russell’ Bermudagrass

Equal Splits†

2008 2009

Source Eatonton Calhoun Eatonton Calhoun-------------------- (lbs of DM/acre) ---------------------

ATU 2 8908‡ 19291 11431 17525ESN 2 6430 16033 8163 17019NSN 2 8704 16985 10226 16464Urea 2 8490 17302 10730 14955Urea 4 7211 18500 8142 15948AN 4 9641 18218 12106 17604Check - 2688 10009 2178 10409LSD0.05 1204 1552 1059 2460† Equal split applications of N that occurred during the season.

Total N applied = 300 lbs N/acre.‡ Items that are in bold font are not significantly

different from the highest value in the column.

Ammonia Volatilization Trap Data 2008-2009 (avg. over two locations)

Ammonia Volatilization Trap Data 2008-2009 (avg. over two locations)

AN4 U4 AN2 U2 ATU SU NSN ESN CON0

20

40

60

80

100

120

1402008 2009

Amm

onia

(NH

4-N

) Vol

atiliz

ation

(p

pm)

Additional DataAdditional Data

Agrotain Treated Ureaas compared to urea applied in the same way (averaged over 4 site-yrs):

• Reduced ammonia volatilization by over 63%.

• Produced 11% more forage yield.• Recovered 19% more of the

applied N.• Did not substantially affect crude

protein content.• Did not substantially affect the

risk of nitrate toxicity.

Another Fertilization Trick

Split Your Potassium Applications!Split Your Potassium Applications!

40-50%in the Spring

50-60%in mid – late season

Poor Stress TolerancePoor Stress Tolerance

Leafspot DiseasesLeafspot Diseases

The Stand is Gone!The Stand is Gone!

Not CompetitiveNot Competitive

Grows Very SlowGrows Very SlowPoor WinterhardinessPoor Winterhardiness

K is for PersistenceK is for Persistence

K is the Key to a Good Stand

K is the Key to a Good Stand

Low Soil pHLow Soil pH

Aluminum Toxicity – Low Soil pH

Aluminum Toxicity – Low Soil pH

Effect of Gypsum on Roots

Alf

afa

Control Gypsum

Alf

alf

a

control treated

Effect of Gypsum (CaSO4) on Root Growth - AlfalfaEffect of Gypsum (CaSO4) on Root Growth - Alfalfa

Increase in root growth over control (%)

0 20 40 60 80 100 120 140 160 180 200 220

Dep

th (

in)

N.a.N.

3

9

15

21

27

33

Source: Dr. M.E. Sumner

Tissue Sampling and Troubleshooting

Tissue Sampling and Troubleshooting

Tissue SamplingTissue Sampling

6 in.

TroubleshootingTroubleshooting

Good Zones• Tissue Sample• Soil Sample• Other(?)

Bad Zones• Tissue Sample• Soil Sample• Other(?)

Representative Samples• ~ 20 similar specimens

Foliar Fertilizer ApplicationsFoliar Fertilizer Applications

• Even if the product is 100% efficient (likely isn’t)

• The most a plant can take up across via the leaves is the equivalent of 1-2 lbs/acre of the nutrient Works for many micro-nutrients (small quantities

needed) Not feasible for macro-nutrients without multiple

applications. (large quantities needed)

• Even if the product is 100% efficient (likely isn’t)

• The most a plant can take up across via the leaves is the equivalent of 1-2 lbs/acre of the nutrient Works for many micro-nutrients (small quantities

needed) Not feasible for macro-nutrients without multiple

applications. (large quantities needed)

QUESTIONS?

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