Fertilization Fundamentals for Hay Producers

Glen Harris

Extension AgronomistUniversity of Georgia - Tifton

Basics of Soil Fertility for Forages

• Nitrogen• pH and Liming• Potassium• Soil Testing

$35.17

$19.36

$3.20

$3.41

$8.95

$20.58

$4.26

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

Bermudagrass Hay Production – 2010Breakdown of Projected Costs

$94.94/ton

0

10

20

30

40

50

60

70

80

90

N P2O5 K2O

Pre=2005200820092010

Fertilizer Prices (cents/lb)

Fertilizer Materials• Single Nutrient –

–Ex. 46-0-0, 0-46-0, 0-0-60• Mixed Grades/Homogenous –

–Ex. 5-10-15• Complete

–Ex. 5-10-15SR, 10-10-10SR• Blends –

–Ex. 46-0-0 + 0-46-0 + 0-0-60• Alternative/Organic

–Ex. Chicken Litter

The Value of a Ton of Broiler Litter

Assumptions:Analysis = 3-3-2

2010 Fertilizer Prices = .45-.25-.50

Availability of N-P-K = 60-80-80 %

• 60#N x .45 x .6 = 16.20• 60#P2O5 x .25 x .8 = 12.00• 40#K2O x .50 x .8 = 16.00

»Total = $44.20

Other Nutrients ?Organic Matter ?Liming ?Nematode Suppresion ?

Soil Testing is the Key !

Source: Foth and EllisSoil Fertility

Why Lime?

Nutrient AvailabilityNutrient UnavailabilityProvide Ca and MgNitrogen FixationBiological Activity

Factors Affecting pH:* Weather (rainfall)* Soil Type* Organic Matter* Tillage & Depth* Nitrogen Fertilizer* Lime* Spatial Variability* Salt

Tons of Calcitic and Dolomitic LimeSold in Georgia (2001-08)

463

54

603

59

411

48

682

149

689

68

598

164

544

160

511

260

0

100

200

300

400

500

600

700

01 02 03 04 05 06 07 08

Dolomitic

Calcitic

63%

DeficiencyWeedsWinterkillLoss of Stand

K is for Persistence !

N with no K can kill a stand in 2 years !

Nitrogen Sources

• Ammonium Nitrate• Urea• UAN Solutions• Ammonium Sulfate• Anhydrous Ammonia• Chicken Litter

Urease Inhibitors: Agrotain

Urease Inhibitor + Nitrification Inhibitor:Agrotain Plus, Agrotain Super U (Nutrisphere-N, Excelis ?)

Fertilizer additive that inhibits degradation of urea by urease(NBPT)

“Agrotain Plus” (for UAN liquids) – also includes a nitrification inhibitor (DCD)

Does not affect microbes (or other soil organisms) directly

Reduces loss of surface applied urea-N to volatilization (up to 14 days under drying conditions) and reduces nitrate leaching

Specialty Fertilizer Products through Southern States

Polymer “Nutrisphere” technology

Active Ingredient =“40 % maleic-itaconic co-polymer”

Claims Urease + Nitrification Inhibition

Mode of action = “shields” N from Nickel for urease and from microbes for nitrification (documented ?)

• Agrium Company• ESN = Environmentally Smart Nitrogen• Polymer Coated Urea• Company = Agrium• “Controlled Release” (not “slow release” ?)• “Releases as the Soil Warms”• Slow Release vs. Split Applications

Closed Chambers - Volatilization

48 49

15

0.30

5

10

15

20

25

30

35

40

45

50

Urea NSN Agrotain Control

N Volatilization – Cotton, 3 Location AverageGlen Harris – UGA, Tifton

NH4mg/L

132

59

44

23

128

46

1.75 0.10

20

40

60

80

100

120

140

Urea Agrotain NSN Control

2008

2009

N Volatilization – Forages, 2 Location AverageDr. Dennis Hancock – University of Georgia, Athens

NH4mg/L

8490 8908 8704

17302

19291

16985

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

Eatonton Calhoun

Urea Agrotain NSN

Dr. Dennis Hancock – UGA, Athens‘Russell’ Bermuda Grass Yields (lbs DM/a) - 2008

1073011431

10226

14955

1752516464

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

Eatonton Calhoun

Urea Agrotain NSN

‘Russell’ Bermuda Grass Yields (lbs DM/a) - 2009Dr. Dennis Hancock – UGA, Athens