Soil and Fertilizer Management Considerations for Forage Systems in GA Dennis Hancock, PhD. Extension Forage Agronomist UGA – Dept. of Crop and Soil Sciences.

Soil and Fertilizer Management Considerations for Forage Systems

in GA

Soil and Fertilizer Management Considerations for Forage Systems

in GA

Dennis Hancock, PhD.Extension Forage Agronomist

UGA – Dept. of Crop and Soil Sciences

Dennis Hancock, PhD.Extension Forage Agronomist

UGA – Dept. of Crop and Soil Sciences

52%

10%

3%

6%

23%

5%

Fertilizer Fuel & RepairsInterest on Var. Costs PesticidesLabor Fixed & Mgmt Costs

Hybrid Bermudagrass Hay – 2008Cost Breakdown

14-15% From ‘08

40% From ‘08

Get a Grip on Your Forage Costs




Fertilizer^

$0.80 - $0.70 - $0.60

Outline

• Overview of Soil Fertility

• Rewards and Risks when Fertilizing Forages Animal Manures Commercial Fertilizer “Enhanced Efficiency” Fertilizer

Products (Nutrisphere, Agrotain, etc.)

Plant NutrientsPlant Nutrients

Element Available Form

Oxygen O2, OH-

Carbon C03-2, HCO3 , CO2

Hydrogen H+, OH-

Nitrogen NO3- , NH4

+

Phosphorus HPO4-2, H2PO4

-

Potassium K+

Macro- (Primary)


Calcium Ca+2

Magnesium Mg+2

Sulfur SO4-2

Meso- (Secondary)


Iron Fe+2 , Fe+3

Copper Cu+2 , Cu+

Zinc Zn+2

Manganese Mn+2 , MnO4-

Molybdenum

HMoO4- , MoO4

-2

Boron H3BO3, B4O7-2

Chlorine Cl-

Micro- (Trace)

Nutrients Removed/Acre With Bermudagrass Hay or Corn

Silage


Silage

0

50

100

150

200

250

300

lbs/

acre

rem

ove

d

Nitrogen Phosphate Potash Calcium Mag

6 Tons Bermudagrass Hay

30 Tons Corn Silage

0

50

100

150

200

250

300

lbs/

acre

rem

ove

d



30 Tons Corn Silage

Soil Test and Follow Fertility Recommendations

Soil Test and Follow Fertility Recommendations

Sample hayfields every year and 1/3 of your pastures each year.

Don’t plug ‘em up, just yet…Don’t plug ‘em up, just yet…

What is holding back hay yields?

DroughtDroughtLow Soil pHLow Soil pH

Inefficient N application methods

Inefficient N application methods

Less effectiveN sources

Less effectiveN sources

Low K fertilityLow K fertility

Insect DamageInsect Damage

Liebig’s Law of the Minimum

Liebig’s Law of the Minimum

Fe

Cl

Ca N

K

P

MnMoS Zn

Cu

B

Mg

Hybrid Bermudagrass Yield Response to N Rate


0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

0 100 200 300 400 500 600 700 800

Nitrogen Rate (lbs N/A)

Forage Yield(tons/A)

@15% moisture

Average or “Normal” Response



0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

0 100 200 300 400 500 600 700 800

Nitrogen Rate (lbs N/A)

Forage Yield(tons/A)

@15% moisture

A Closer Look at Bermudagrass Yield Response to N Rate


The False Economy of Shortcuts

The False Economy of Shortcuts

Cost of Production Compared to Average

Yield (t/ac) 60% 75% 90% 100% 110% 125%

8 $56 $71 $85 $94 $103 $118

7 $64 $80 $96 $107 $118 $134

6 $75 $94 $113 $125 $138 $156

5 $90 $113 $135 $150 $165 $188

4 $113 $141 $169 $188 $207 $235

3 $150 $188 $225 $250 $275 $313 Adapted from R.C. Lacy, 2008

A Closer Look at Bermudagrass Yield

Response to N Rate


Response to N Rate

0

2000

4000

6000

8000

10000

Yie

ld (

lbs

DM

/acr

e)

0 150 3000

2000

4000

6000

8000

10000

Yie

ld (

lbs

DM

/acr

e)

0 150 300

N Applied During the Season(lbs actual N/acre)

Eatonton 2007(Drought Year)

N Fertilizer Applications: Chemistry


Ammonium Nitrate Urea

Uric Acid



Ammonium Nitrate

NH4+

----N03

-



R-(NH2)2

(Urea, Uric Acid, etc.)

+ H20

urease

2NH3 2NH4+

+ 2H+

N Application StrategiesN Application Strategies

M A M J J A S O

Green-up Only


M A M J J A S O

Green-up Only


M A M J J A S O

Green-up & After 2nd Cut


M A M J J A S O

Green-up & After 2nd Cut


M A M J J A S O

Green-up & After Each Cut

N Concentration in the Forage Crop


Days of Growth

Gro

wth

of

the C

rop

Nitra

te C

on

c. in th

e

Cro

p



Days of Growth

Nitra

te C

on

c. in th

e

Cro

p5000 ppm

Rec. Rate

2 x Rec. Rate

3 x Rec. Rate



Days of Growth

Nitra

te C

on

c. in th

e

Cro

p5000 ppm

Drought



Days of Growth

Nitra

te C

on

c. in th

e

Cro

p5000 ppm

Rec. Rate

2 x Rec. Rate

3 x Rec. Rate

Monitor Climate PredictionsMonitor Climate Predictions

http://www.cpc.ncep.noaa.gov/

Monitor Climate PredictionsMonitor Climate Predictions

http://www.cpc.ncep.noaa.gov/products/predictions/90day/


Response to N Rate


Response to N Rate

0

2000

4000

6000

8000

10000

Yie

ld (

lbs

DM

/acr

e)

0 150 3000

2000

4000

6000

8000

10000

Yie

ld (

lbs

DM

/acr

e)

0 150 300

N Applied During the Season(lbs actual N/acre)

Eatonton 2007(Drought Year)



Split Timing Jun. 7 Jul. 17 Aug. 15 Oct. 1 Total

- - - 521 e 824 d 39 c 474 c 1858 d

150 N greenup only 2764 bc 2043 bc 130 c 506 c 5442 c

150 Ygreenup & after 2nd cut 1921 bc 1450 cd 1620 b 663 c 5652 bc

150 YBefore ea. growth period 939 de 1946 bc 695 c 1644 b 5224 c

300 N greenup only 3999 a 3031 a 399 c 684 c 8113 ab

300 Ygreenup & after 2nd cut 3082 ab 2341 ab 2854 a 1542 b 9819 a

300 YBefore ea. growth period 1841 cd 3026 a 1734 b 2458 a 9058 a

2152 2094 1067 1139 64521167.2 870.1 823.2 411.4 2582.0

36.5 28.0 51.9 24.3 26.9

Source and Total Application Rate

Check

LSD (P<0.05)CV (%)

Urea

Average

Eatonton 2007

A Fertilization TrickA Fertilization Trick

• Long-term, this can increase yields by 5-10% and increase NUE by 25-30% Especially important under extremes

Leaching Volatilization (in the case of urea-based

products) Late freeze Drought

• Helps to prevent NITRATE TOXICITY!

Split Your Nitrogen Applications!Split Your Nitrogen Applications!

Fertilization StrategiesFertilization StrategiesNew N Fertilizer ProductsNew N Fertilizer Products

Enhanced Efficiency Fertilizer•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

Nitrogen Use EfficiencyNitrogen Use Efficiency

Eatonton

Calhoun 2008

SourceTotal Application Rate

Timing of Equal SplitsJun. 12 Jul. 25 Sep. 03 Oct. 16 Total

Nutrisphere 300 greenup & after 2nd cut 6290 a 3018 cd 5863 a 1814 c 16985 bc

ESN 300 greenup & after 2nd cut 4923 b 4167 ab 4257 b 2685 ab 16033 c

Agrotain-treated Urea 300 greenup & after 2nd cut 6804 a 4337 ab 6093 a 2058 bc 19291 a

Broiler Litter/Urea 300broiler litter at greenup, urea after 2nd cut

5817 ab 2701 de 5291 ab 2251 abc 16060 c

Urea 300 greenup & after 2nd cut 6495 a 3536 bc 5452 a 1819 c 17302 bc

Urea 300before each growth period

6013 a 4588 a 5030 ab 2870 ab 18500 ab

Ammon. Nitrate 300before each growth period

5891 ab 4147 a 5191 ab 2989 a 18219 ab

Check - - 4221 c 2118 e 2215 c 1455 c 10009 d

5807 3576 4924 2243 165501084.0 823.7 1088.3 855.1 1889.1

12.7 15.7 15.0 25.9 7.8LSD at 5% LevelCV (%)

Average

Nitrogen Use EfficiencyNitrogen Use Efficiency

Eatonton 2008

Source

Total Application Rate Timing of Equal Splits Jun. 12 Jul. 25 Sep. 03 Oct. 16 Total

Nutrisphere 300 greenup & after 2nd cut 3838 a 1633 d 2945 a 287 c 8704 ab

ESN 300 greenup & after 2nd cut 920 c 3134 ab 1934 b 443 ab 6431 c

Agrotain-treated Urea 300 greenup & after 2nd cut 3346 a 2496 b 2731 a 334 b 8908 ab

Broiler Litter/Urea 300 broiler litter at greenup, urea after 2nd cut

1821 b 2449 c 2807 a 363 abc 7440 bc

Urea 300 greenup & after 2nd cut 3104 a 2414 c 2682 a 292 c 8490 ab

Urea 300 before each growth period 1934 b 3257 a 1614 b 407 abc 7211 bc

Ammon. Nitrate 300 before each growth period 3361 a 3518 a 2292 ab 470 a 9641 a

Check - - 435 c 1868 cd 272 c 113 d 2688 d

2345 2596 2160 339 74391144.6 652.3 722.4 131.0 1887.5

33.2 17.1 22.7 26.3 17.3LSD at 5% LevelCV (%)

Average

New N ProductsNew N Products

??



Fertilizer^

$0.80 - $0.70 - $0.60

Another Fertilization TrickApply P in late summer or fall.Apply P in late summer or fall.

• P can essentially be applied any time during the year on established forage crops.

• Purchase P fertilizer in “off-peak” times of the year (i.e., summer and fall) Demand for the product is low Demand for spreading services is low Less risk of P runoff

• P can essentially be applied any time during the year on established forage crops.

• Purchase P fertilizer in “off-peak” times of the year (i.e., summer and fall) Demand for the product is low Demand for spreading services is low Less risk of P runoff

Another Fertilization TrickSplit Your Potassium Applications!Split Your Potassium Applications!

40-50%in the Spring

50-60%in mid – late season

Potash also determines competitiveness in

bermudagrass

Potash also determines competitiveness in

bermudagrass

Leafspot and winterhardiness

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

Increase Corn GrainIncrease Corn GrainDries down slowerDries down slower

Later MaturingLater Maturing

K Effects on Corn SilageK Effects on Corn Silage

Faster Body Weight RecoveryFaster Body Weight Recovery

DO NOT cut back on lime!DO NOT cut back on lime!

Get your priorities right!

1. Lime is still job #1.

Get your priorities right!

1. Lime is still job #1.

How Soil pH Affects Availability of Plant Nutrients

The Difference of a soil pH of 5.8 vs. 6.2

NutrientAmt. Used Annually

Unit Price

Dec. in Efficiency

Value of Decrease

(Lbs/acre) ($/lb) ($/acre)

N 200 $0.85 20% -$34P2O5 50 $0.80 25% -$10K2O 150 $0.60 10% -$ 9

Total -$53

What’s a Common Soil pH Value

What’s a Common Soil pH Value

S. Piedmont

Fertilization StrategiesFertilization Strategies

Hayfield 2 & 3pH = 5.5P = 15K = 90OM = 1.5%

Hayfield 2 & 3pH = 5.5P = 15K = 90OM = 1.5%

Hayfield 1pH = 6.0P = 25K = 120OM = 2.5%

Hayfield 1pH = 6.0P = 25K = 120OM = 2.5%

Costs Increase When Soil Fertility Decreases


Recommended Rate of

P & K Fertility N P2O5 K2O

Total Cost

------------- (lbs/acre) ------------- ($/acre)

V. High 250 0 0$187.5

0

High 250 30 150

318.59

Medium 250 60 200

352.17

Low 250 80 250

439.57

Assumptions: Using 32% UAN ($480/ton), DAP ($1300/ton), and Muriate of Potash ($780/ton).

Let’s assume P & K have been equally taken care of or equally neglected. So, let’s consider bermudagrass fertility.

If you must cut back…If you must cut back…

Do so uniformly!• If the recommendation is for N, P, and K,

be sure to apply each. Don’t just apply N!!! IMPORTANT Do a total reduction (by a percentage).

• Base the reduction in P and/or K off of the N reduction If you reduce N by 20% from the Rec. Rate… Then reduce the other recommended rates

by 20% EXCEPTION: If your soil is “Very Low.”

Do so uniformly!• If the recommendation is for N, P, and K,

be sure to apply each. Don’t just apply N!!! IMPORTANT Do a total reduction (by a percentage).

• Base the reduction in P and/or K off of the N reduction If you reduce N by 20% from the Rec. Rate… Then reduce the other recommended rates

by 20% EXCEPTION: If your soil is “Very Low.”



Recommended Rate of

P & K Fertility N P2O5 K2O

Total Cost

------------- (lbs/acre) ------------- ($/acre)

V. High 200 0 0$150.0

0

High 200 24 120

254.87

Medium 200 48 160

307.74

Low 200 64 200

351.65

Assumptions: Using 32% UAN ($480/ton), DAP ($1300/ton), and Muriate of Potash ($780/ton).

Let’s assume P & K have been equally taken care of or equally neglected. So, let’s consider bermudagrass fertility.

Let’s cut back by 20%.

Broiler Numbers Layer Numbers

A Major Fertility AdvantageA Major Fertility Advantage

Poultry Litter for Hay FieldsPoultry Litter for Hay Fields

• An excellent source of fertility, when used wisely.

• N release is skewed to the summer months.

• Weed pressure does increase Not a source of weed seed Changes the fertility and makes

broadleaf weeds more competitive.

• Potassium fertilization may not be adequate Poultry Litter: 3-3-2 Ideal bermudagrass fertilizer: 4-1-

3

Variability in Chicken LitterVariability in Chicken Litter

• “Book Number” 3-3-2

• Range in % N 1.1 – 4.9%

• Range in % P2O5

0.9 – 4.8%

• Range in % K2O 1.2 – 4.0%

• “Book Number” 3-3-2

• Range in % N 1.1 – 4.9%

• Range in % P2O5

0.9 – 4.8%

• Range in % K2O 1.2 – 4.0%

Source: Univ. of Ark. Ext. Bulletin FSA-8000.

Foliar Fertilizer ApplicationsFoliar Fertilizer Applications

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

• The most a plant can take up will be 1-2 lbs of nutrients 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 will be 1-2 lbs of nutrients Works for many micro-nutrients (small quantities

needed) Not feasible for macro-nutrients without multiple

applications. (large quantities needed)

Doing Many Things Well

FFFFFFFA

F


Silage


Silage

0

50

100

150

200

250

300

lbs/

acre

rem

ove

d



30 Tons Corn Silage

0

50

100

150

200

250

300

lbs/

acre

rem

ove

d



30 Tons Corn Silage

Nutrients removed per acre in a typical weaned beef calf.

Nutrients removed per acre in a typical weaned beef calf.

0

50

100

150

200

250

300

lbs/

acr

e r

em

oved


500 lb animal

0

50

100

150

200

250

300

lbs/

acr

e r

em

oved


500 lb animal

Adapted from S. Forages 3rd Ed.

Efficiency of Four-legged Manure Spreaders

Efficiency of Four-legged Manure Spreaders

White et al., 2001 J. Environ. Qual. 30:2180–2187

Nutrient Distribution in Pastures

Nutrient Distribution in Pastures

Mechanical

Hay 30-70%

Silage 60-85%

Green Chop 70-95%

Efficiencies of Grazing and Mechanized Harvest

Efficiencies of Grazing and Mechanized Harvest

Method Efficiency

Grazing

Continuous Stocking 30-40%

Slow Rotation (3-4 paddocks) 50-60%

Moderate Rotation (6-8 paddocks)

60-70%

Strip Grazing 70-80%

QUESTIONS?QUESTIONS?

www.georgiaforages.com1-800-ASK-UGA1

www.georgiaforages.com1-800-ASK-UGA1

Soil and Fertilizer Management Considerations for Forage Systems in GA Dennis Hancock, PhD. Extension Forage Agronomist UGA – Dept. of Crop and Soil Sciences.

Documents

forage costs fertilizer

hay yields

hayvalue of hayvalue

forage systems

n rateaverage

extension forage agronomistuga

elementavailable form

rate lbs naforage yieldtonsa