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Rotational Grazing Recycles Nutrients

Authors as Published

Peter Callan, Extension Agent, Farm Business Management, Northern District (peter.callan@vt.edu),

Due to the dramatic increase in fertilizer prices over the past six months, producers are wondering how they can get the most bang for their buck with limited funds for fertilizer and lime purchases.  A current soil test takes out the guesswork and prevents the producer from under or over-applying lime and fertilizer, either of which will decrease your efficiency and profitability.  Virginia Tech soil test laboratory recommendations are based on research conducted for Virginia soils and climate.  Livestock producers can reduce fertilizer purchases by implementing rotational grazing systems on their farms.

Rotational grazing is a management intensive system that concentrates animals within a relatively small area (paddock) for a short period of time, e.g. 1-3 days for beef cattle.  Pastures are divided into multiple paddocks using a temporary fence.  Moving livestock to another paddock before over-grazing allows the forage to recover and resume growth.  Animals are moved according to a flexible schedule based on herd size, the amount of land available, quality of forages in the paddock, and forage consumption.

Missouri[1] researchers estimated that grazing animals recycle 75-85% of forage nutrients consumed.  An even distribution of manure throughout a paddock is required for productive plant growth.  Intensity of grazing rotations affects the manure coverage in paddocks.  In an intensive rotational grazing system there is an even distribution of manure because animals compete for the available forage in the paddock before being moved to another paddock.  The Missouri researchers calculated that under continuous grazing practices it would take 27 years to obtain one manure pile per every square yard within a pasture.  Conversely, it would take 2 years to achieve the same manure pile density using a two-day rotation.[2]

The location of hay feeding areas also impact the distribution of nutrients within a field with most manure being deposited near the feeding areas.  Depending on weather conditions and the potential for creating ruts in the pasture, feeding areas should be moved throughout the pasture to insure a more even distribution of nutrients.  Whenever hay is baled, nutrients are removed from the field and exported to the feeding area.  Kentucky researchers have estimated that a ton of grass hay (fescue, orchard grass) removes the following nutrients from the soil:  12 lbs. of phosphate and 50 lbs. of potash.[3]  If these nutrients are not replaced, nutrient availability from the soil will be depleted over time.  Consequently, there will be a reduction in hay and forage yields.  Soil testing determines the amount to fertilizer that needs to be applied to maintain hay yields.

Cooperative extension educators can assist producers in the design of rotational grazing systems for their farms.  Virginia Cooperative Extension work has shown that the implementation of rotational systems can maximize profitability for cow/calf producers.  There are Virginia livestock producers who have reported increased net profits of $200 per head due to the implementation of rotational grazing systems on their farms.  Rotational grazing systems can maximize farm profitability by recycling nutrients which results in a major reduction of purchased fertilizer inputs.


[1] Bellows, B.  2001.  Nutrient Cycling in Pastures.  National Sustainable Agriculture Information Service.
[2] Lory, J. and C. Roberts.  2000.  Managing nutrients in pastures to improve profitability and water quality.  In: G. J. Bishop-Hurley, S.A. Hamilton, and R. Kallenbach (eds.), Missouri Dairy.
[3] Smith, R.  2008.  Soil Test Should Drive Fertilizer Decisions.  Hay and Forage Grower.

Rights


Virginia Cooperative Extension materials are available for public use, re-print, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.

Publisher

Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Alan L. Grant, Dean, College of Agriculture and Life Sciences; Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; Jewel E. Hairston, Administrator, 1890 Extension Program, Virginia State, Petersburg.

Date

April 8, 2011