GameKeepers Emag

Gamekeepers Winter 2015

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Page 131 of 155

130 A utilization cage is the best way to tell whether or not your food plots are being effective. Obviously inside the cage you can see the potential of your plants and on the outside what your herd is consuming © Jesse Raley 2 feet, then the area is 2' x 2' = 4 ft2. If the cage is circular shaped, then use the following formula area = pi x r2, where pi = 3.14 and r = radius (which is half of the diameter). So, let's say the diameter of your circular cage is 3 feet, simply divide the diameter by 2, square the radius, and multiply by 3.14. For example, 3 ÷ 2 = 1.5, now multiply 1.5 x 1.5 = 2.25, and finally, multiply 2.25 x 3.14 = 7 ft2. Now that you know the area of your exclusion cage, you need to scale your meas- urements on a per-acre basis. There are 43,560 ft2 in an acre, so we simply divide the area of an acre by the area of our cage (43,560 ÷ 7 = 6,223). Now multiply the weight of your forage sample from inside the exclusion cage by 6,223. So if we col- lected 0.5 pounds of forage from inside the cage, our per-acre amount would be 6,223 x 0.5 = 3,112 pounds of forage per acre. Keep in mind this is the wet weight, which includes the weight of the water. Researchers go one step further and dry the forage in a special oven to remove the water weight, but that's not necessary for you to do as long as you weigh the forages fairly soon after cut- ting them. "Figure 1" shows some clover forage data collected by the Mississippi State University Forage Lab and demon- strates what you can learn from the growth habits of different forages from place to place and year to year. Now you have an accurate estimate of the amount of forage produced over the time period you measured (2 weeks, 1 month, etc.), but this is only half of the equation. Your next step is determining deer utilization. After all, forage that produces the most biomass is useless if deer don't eat it! Utilization is measured as the differ- ence between the amounts of forage inside versus outside the exclusion cage. For example, let's say you clipped the amount inside the cage and calculated the weight as 0.5 pounds. Now you have to clip the amount on the outside by clipping down to the same height near the ground as you did inside the cage. If you clipped all the forage down to 3 inches inside the 7ft cage area, you should clip down to the same 3-inch height outside the cage in a 7ft area. Let's say the weight of the forage out- side the cage was 0.2 pounds – therefore, the amount of forage utilization on a per- acre basis is 3,112 – 1,245 = 1,867. So, our food plot is producing 3,112 pounds of forage and deer have consumed 1,867 pounds, on a per-acre basis. Calculating both the amount of forage produced and the amount consumed will help you determine which forages are the best for your property. See "Figure 2" for a dia- gram showing how to collect forage for these measurements.

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