NDSU Extension Range and Forage Production SAMPLE KITS

Accurately calculating range and forage production of grazing resources is important when estimating carrying capacity and stocking rate. The most accurate method to calculate forage production is the clip-and-weigh method.

This method requires the harvesting of standing forage at a given time to predict available forage. The available forage is measured by hand clipping and weighing a specified number of plots within a grazing/forage production area.

These plot weights are averaged to account for variability in production across the field or pasture to be grazed. The average plot weights then are multiplied by a conversion factor to determine the approximate pounds per acre of production.

This production parameter only provides a measurement of plant production and not necessarily forage production because some of the weight may be weedy species that livestock may not consume. To avoid overestimating the stocking rate, clip only the plants found within your frame that the scheduled class of livestock will consume.

The following supplies are required for your Range and Forage Production Sampling Kit:

• Range hoop/frame (Refer to the appropriate pasture or field type section below to determine best frame size to use)
• Clippers
• Scale to measure weight in grams
• Paper/plastic bag to place clipped forage in for weighing
• Markers to label bags
• Paper or forms to record data
• Pen or pencil to record data

Photo Credit:

Miranda Meehan, NDSU

When calculating forage production, use the following protocol:

1. Select sample sites to clip within the grazing unit, being careful to represent any variation (kinds and amount of plants) in forage composition and production. The number of sites selected will depend on the type of grazing resource and uniformity of vegetation; refer to the appropriate pasture or field type section for recommendations on the number of frames. The size and shape of the plots depend on the type of forage to be sampled. Frames can be circular, square, rectangular or linear (Table 1). Sample sites should be selected randomly within each sampling area.

   Table 1. Common plot sizes and conversion rates.

   Plot Area (ft2)	Plot Circumference (inches)	Plot Dimensions (inches)	Conversion Rate
   1.92	58.94	16.632 x 16.632	50
   10.76	139.56	39.36 x 39.36	8.92

   Adapted from the U.S. Department of Agriculture Natural Resources Conservation Service National Range and Pasture Handbook

2. Clip plants within the frame that will be consumed by livestock and/or wildlife. Total biomass is determined by harvesting the whole plant, clipping to ground level. If a shrub is within the frame and is a type that will be consumed, only harvest the current year’s growth. When clipping, include plants whose stems originate within the frame and collect all above-ground parts that extend beyond the frame boundary, irrelevant of height. Do not clip plants with stems outside of the frame, even though some plant parts may overlap the frame.

3. Harvest, weigh and record the weight for each frame. Then calculate the average weight in grams, remembering to subtract the weight of the empty bag from the weight of each sample.

4. After all forage is weighed, determine air-dried weight. The recommended method is to air-dry the harvested material. Typically, harvested material is collected in paper bags and placed in a dry area with exposure to direct sunlight for several days to air-dry the material. Air-dried weights also can be estimated by selecting the appropriate factor from Table 2 and multiplying by this percentage to get air-dried weight.
   Table 2. Percent of air-dry matter of forages by stage of growth.

5. 	Before Heading – Initial growth to boot stage	Headed – Boot stage to flowering	Seed Ripe – Leaf tips drying	Leaves Dry – Stems partly dry	Dormancy
   Cool-season Grasses
   Wheatgrasses, needlegrasses, perennial bromes, bluegrasses, fescues, annuals such as oats, barley	35%	45%	60%	85%	95%
   Warm-season Grasses
   Tall: bluestems, switchgrass, corn, sorghum, millet	30%	45%	60%	85%	95%
   Mid: side-oats grama, teff	40%	55%	65%	90%	95%
   Short: blue grama, buffalograss	45%	60%	80%	90%	95%
   Other Range or Pasture Plants
   Forbs	20%	40%	60%	90%	100%
   Shrubs	35%	50%	30%	85%

   Adapted from the USDA NRCS National Range and Pasture Handbook

6. Next, multiply the average dry weight by the conversion factor for the frame (refer to the appropriate pasture or field type section below or Table 1). This number will be equal to the weight in pounds per acre.

7. Finally, multiply the weight in pounds per acre by the area (in acres) of the grazing unit (pasture/field) to determine forage production.

Once you determine the forage production for a grazing resource, you can calculate carrying capacity and stocking rate.

Determining the carrying capacity and establishing the proper stocking rate is important for optimizing forage production and maintaining animal performance while ensuring the sustained health and production of the grazing resources. Refer to NDSU Extension publication “Determining Carrying Capacity and Stocking Rates for Range and Pasture in North Dakota” (R1810) and the “NDSU Grazing Calculator” (https://www.ndsu.edu/agriculture/ag-hub/ag-topics/livestock/tools/grazi…) for more information on completing these calculations.

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