Grazing Management Effects on Pasture Growth: Risks and Rewards Geoff Brink U.S. Dairy Forage Research Center USDA-ARS

Introduction • Clipping vs. Grazing – why they’re different. • How we conducted this research. • Results – just the facts. • Implications – what does it mean to you?

Clipping vs. Grazing • Clipping is cheaper, faster, easier, and less

variable than grazing.

Clipping vs. Grazing • In theory, defoliating grass with a blade or an

animal’s mouth should be the same.

Clipping vs. Grazing

Nutrient equivalent of manure and urine

Mineral Equivalent rate (lb/acre) Nitrogen 900 800 Phosphorus 250 10 Potassium 350 650 Sulfur 100 50 Calcium 650 10 Magnesium 200 10

meadow fescue MDF orchardgrass OGR quackgrass QGR reed canarygrass RCG

• How we conducted this research.

20"

5"

2"

10" 12"

6" 3" 1"

Vegetative

Mature

Stubble height

Research site at Prairie du Sac

Heifers grazing vegetative grass

Heifers grazing mature grass

Before and after each grazing event

At the end of the grazing season

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Results for vegetative grass

Annual grazed yield (lb DM/acre) @ vegetative stage

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MDF OGR QGR RCG

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Yield distribution of orchardgrass @ vegetative stage

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Digestibility of orchardgrass @ vegetative stage Di

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Persistence (tillers/ft2) @ vegetative stage in 2009

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Persistence (tillers/ft2) @ vegetative stage in 2010

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6 in. residue 3 in. residue 1 in. residue

Orchardgrass in November, 2009

April 28 May 4 May 11

Date when grazing began in 2010

Grazing vegetative grass:

1) There is no annual yield reward for grazing lower than 3 inches, but there is risk of killing grass and delaying growth the following spring. • Reducing residue height for even one grazing

event can reduce future productivity. 2) Take half – leave half management reduces

annual yield; the rewards are shorter rotation intervals and earlier grazing in the spring.

3) Forage quality is relatively unaffected by residue height.

Results for mature grass

Annual grazed yield (lb DM/acre) @ mature stage

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ss g

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Persistence (tillers/ft2) @ mature stage in 2009

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Persistence (tillers/ft2) @ mature stage in 2010

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Grazing mature grass:

1) Annual yield is increased by grazing lower than 5 inches, but there is risk of delaying growth the following spring. • Rhizomatous grasses may be more sensitive to

residue height than bunch grasses. 2) Because grass is mature and livestock are

generally not forced to graze closely, there is: • no reward for leaving a tall residue. • little risk of damaging pasture when mob

stocking.

Surface litter at end of season (lb/acre)

2009 2010

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The Bottom Line:

Grass at vegetative stage of maturity is at greater risk of damage from poor grazing management than mature grass.

Grass under stress (moisture, fertility) is at greater risk of damage from poor grazing management than healthy grass.

Grazing Management Effects on Pasture Growth:�Risks and RewardsIntroductionClipping vs. GrazingClipping vs. GrazingClipping vs. GrazingSlide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Precipitation (in.)Average annual grazed yield�(lb DM/acre)Slide Number 16Annual grazed yield (lb DM/acre)�@ vegetative stageSlide Number 18Slide Number 19Persistence (tillers/ft2) �@ vegetative stage in 2009Persistence (tillers/ft2) �@ vegetative stage in 2010Slide Number 22Grazing vegetative grass:Slide Number 24Annual grazed yield (lb DM/acre)�@ mature stageSlide Number 26Slide Number 27Persistence (tillers/ft2) �@ mature stage in 2009Persistence (tillers/ft2) �@ mature stage in 2010Slide Number 30Slide Number 31Slide Number 32Grazing mature grass:Surface litter at end of season (lb/acre)The Bottom Line: