GRAZING DAYS

Pasture ManagementJuly 23, 2009

Why a Soil Test

We can’t mange what we can’t measure. With an accurate soil test, a strategy can be made to solve even the most difficult of problems

• Encourages plant growth by providing the best lime / fertilizer recommendations

• Promotes environmental quality• Saves money

What is a Soil Test

A soil test is a process by which elements (phosphorus, potassium, calcium, magnesium, sodium, sulfur, manganese, copper and zinc) are chemically removed from the soil and measured for their "plant available" content within the sample. The quantity of available nutrients in the sample determines the amount of fertilizer that is recommended. A soil test also measures soil pH. These analyses indicate whether lime is needed and, if so, how much to apply.

A routine soil test consists of:

• pH and lime requirement• Calcium• Magnesium• Phosphorus• Potassium

Can add organic matter if desired.

The soil testing puzzle is made up of three parts.

Taking the sample

UF-ESTL Available TestsTest A ($3.00)• pH• Lime requirement

Test B ($7.00)• Test A +• P, K, Mg

Photo Credit: Amy Shober, UF-IFAS

Lab procedures

Dry Screen Scoop Extract Measure

Soil Test Interpretation

V. Low Low Med. High V. High

Fertilizer responseexpected

No responseexpected

Sufficiencysoil test value

V. Low Low Med. High V. High

Fertilizer responseexpected

No responseexpected

Sufficiencysoil test value

Soil Test Results

Soil Test Phosphorus (Lbs/Acre)

Rela

tive Y

ield

(%

)

0 20 40 60 80 100 120 140

0

20

40

60

80

100

L M Optimum High

$

Amy Shober, UF-IFAS

18 essential plant nutrients:

From air/water

Carbon = C

Hydrogen = H

Oxygen = O

From soil and fertilizer

Macro-Nutrients

Nitrogen = N

Phosphorus = P

Potassium =K

Calcium =Ca

Magnesium = Mg

Sulfur = S

Micro-Nutrients

Manganese =Mn

Zinc = Zn

Copper = Cu

Iron = Fe

Boron = B

Molybdenum = Mo

Chlorine = Cl

Nickel = Ni

Cobalt = Co

Nitrogen

Relative quantitiesof soil-suppliednutrients in dryplant tissue.

Potassium

Phosphorus

Calcium

Magnesium

Sulfur

All micronutrients combined

Quickness of nutrient availability

• Soil minerals• Organic matter• Fertilizer

Very slow

Very fast

Availabilityto plants

Soil nutrient deficiency:Add fertilizer, get a response

FERTILIZER UPDATE

The future of N fertilizers

• N fertilizer comes from air, hydrogen (from natural gas), heat, and pressure.

• It is more economical to produce N off-shore where natural gas is cheap.

• The USA is now a net importer of N.• Our future N supply may be dominated by

urea produced overseas.

The future of P fertilizers

• Single superphosphate and triple superphosphate are no longer produced in Tampa.

• Production is now limited to mono-ammonium phosphate (MAP) and di-ammonium phosphate (DAP).

• Florida still has mineable P ore, but the mines are moving to the south.

The future of K fertilizers

• Saskatchewan province in Canada has several hundred years worth of mineable K salts.

• Price will be driven by worldwide demand, particularly from China and India.

Economics of Hay ProductionElena Toro, Suwannee Co. and Dan Fenneman, Madison Co. Extension Agents

Fertilizers Cost per Ton Cost per Unit/Ton

Cost to apply 80 lbs N/ Acre

Amm Nitrate 34-0-0 $350 $0.51 $41.18

375 .55 44.12

Amm Sulfate 21-0-0 250 .60 47.62

240 .57 45.71

Coated Urea 46-0-0 750 .82 65.22

Liquid 24-0-3 180 .38 30.00

28-0-0 243 .43 34.70

32-0-0 280 .44 34.99

Potash 0-0-60 675 .56 45.00

710 .59 47.33

Economics of Hay ProductionElena Toro, Suwannee Co. and Dan Fenneman, Madison Co. Extension Agents

Commercial Blends

Cost per Ton Unit per Ton 80 lbs N & K / Acre

20-0-20 $463.47 $1.16 $92.69

19-5-19 462.27 1.22 97.32

18-4-18 436 1.21 96.89

16-4-16 393 1.23 98.25

20-4-10 N 365 .91 73.00

K 365 1.83

WEED CONTROL UPDATE

Control of Annual Weeds

0

2 0

4 0

6 0

8 0

1 0 0

1 2 0

Emerg. Seed. Veg. Flower Mat.

Wee

d C

on

tro

l

Control of Biennial Weeds

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1 0

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3 0

4 0

5 0

6 0

7 0

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9 0

1 0 0

Emerg Veg Rosette Bolting Flow ering

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d C

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Fall

Late Summer

Winter Spring

Control of Perennial Weeds

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Dorm. Veg. Bud Flower Fruiting Fall

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Weed Control

What are the options?– Spray– Fertilize– Spray and fertilize– Mow– Do nothing

30

Bermudagrass, Ragweed and NitrogenL

bs/

be

rmu

da

/ac

N = 34 lbs/ac John Boyd, U of Arkansas

31

34 lb N will cost $20 - $40/AHerbicide will cost $8 - $25/A

Lb

s/b

erm

ud

a/a

c

N = 34 lbs/ac John Boyd, U of Arkansas

32

Herbicides, Mowingand Bermudagrass Yield

Lbs

/ac

Heavily infested with wooly croton and ragweed Baumann Texas A&M

PASTURE WEEDS

Blackberry (bush-type)

Blackberry Control

• Remedy - 1 qt/A• Pasturegard - 2 qt/A• Cimarron - 0.5 oz/A ( injury to Bahia)• Telar - 1.0 oz/A

• Do not mow within 1 yr of treatment• Blackberry is most sensitive when blooming

Dogfennel Control

• Weedmaster – application rate is highly dependant on DF size.– up to 12 inches – 2 pt– 12 to 24 inches – 3 pt– >24 inches – not recommend WM

• Often inconsistent control.

Dogfennel control

• Pasturegard – 2 pt will relatively good control on DF up to 24-30”.

• 3 pt never misses, even on big stuff. • Price keeps PG from being used more often

Cleanwave

• Active ingredient: fluroxypyr• Volatility: moderate• Use rate: 14 oz/A (for now)• Price: ~ $0.50 per ounce.

Control of 3’ tall dogfennel

Herbicide % control

6 WAT

$/A

Cleanwave (14oz) + 2,4-D (3pt)

90 12

Weedmaster (2 pt) 50 8

Weedmaster (3 pt) 80 12

Weedmaster (4 pt) 90 16

Cleanwave + 3pt 2,4-D

Weedmaster 2 pt

Weedmaster 3pt

August dogfennel treatment – Useless, right???

Brent Sellers, Univ. of Florida

5 months later – this field will explodedwith grass in spring

Brent Sellers, Univ. of Florida

5 months later – this field will explodedwith grass in spring

Treatment with Pasturegard 3 pt/A ($23/A) more than doubled grass production. Is it worth it to you?

Brent Sellers, Univ. of Florida

Prickly Pear

Prickly Pear Control

• Do not mow! These reproduce veg. and the mowed pads can root and colonize.

• Herbicides- Remedy + basal/diesel fuel – spray one at a

time.- Pasturegard is same as Remedy- 2,4-D is not effective- What about Cleanwave?

Before

After

Recommendation

• Cleanwave at 50 oz/A.• We applied in the fall (October).

• Spring applications????

Florida Pusley

Control of 6” pusley

Herbicide Rate Pusley Control (%)

2 weeks 8 weeks

Cleanwave 14 oz/A 14 18

Weedmaster 3 pt/A 56 70

Pasturegard 3 pt/A 48 84

Forefront 2 pt/A 55 90

Forefront + CW 2 pt + 14 oz 73 99

Forefront + PG 2 pt + 1 pt 90 100

Sedges

• Outrider – sulfosulfuron• Use rate: 1.33 oz/A• Cost - $20/A• 0 day grazing, 14 day haying restriction

• Safe on established Bermuda and Bahia

TSA Control

% Control

Herbicide Rate 3 MAT 6 MAT 12 MAT

Remedy 1 qt 90 70 50

Pasture gard

1.5 qt 80 60 40

750 7 oz 95 90 85

Horsenettle

• Remedy - 2 pt at bloom– Acceptable control but somewhat weak

• Milestone is excellent– Use at least 3 oz/A, 5 oz is better.

Wild Radish

Control of Wild Radish

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10

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70

80

90

100

2,4-D

seedling

rosette

bolting

flower

2,4-D 1 pt University of Georgia

Thistle Control

>90% Thistle Control

Growth Stage Herbicide $/A

Rosette 2,4-D $6

Bolting Weedmaster $12

Flowering Milestone $20

What about BIG weeds

Milestone is the best option

• References

Dr. Obreza, Soil and Water Science

Dr. Ferrell, Weed Science

Dr. Sellers, Weed Science