Forages:Topics:Pasture Yield

Topics : Pastures : Determining Pasture Yield

Determining Pasture Yield

Introduction
Methods of Determining Pasture Yield
Calculate Your Pasture Yield
How to Calibrate Indirect Methods
Examples of Pasture Yield Calculations

Additional pasture information via the Forage Information System (FIS)

Examples of Pasture Yield Calculations

To estimate how much forage is consumed by the grazing animals you need to estimate the DM before and after each grazing event. The subtraction of pre-grazing DM minus post-grazing DM will be the actual forage consumed.

Using Pasture Ruler

Pre-Grazing

Post-Grazing

Sample Number	Plant Height (in)
1	5
2	10
3	12
4	7
5	6
6	11
7	13
8	9
9	6.5
10	9
11	10
12	8
13	11
14	7
15	12
16	13
17	7.5
18	9
19	5.5
20	9
Sum = 180.5 in
Average height = 180.5/20= 9.025
Pre-grazing yield = 9.0*300 lb DM//in/A Pre-grazing yield = 2700 lb DM//A

Sample Number	Plant Height (in)
1	1.5
2	2
3	5
4	3
5	2
6	3
7	3.5
8	2
9	1.5
10	2
11	2.5
12	1
13	3.5
14	2
15	3
16	4
17	2
18	1.5
19	1
20	2
Sum = 48 in
Average height = 48/20= 2.4
Post-grazing yield = 2.4*300 lb DM//in/A Post-grazing yield = 720 lb DM//A

Total forage consumed = Pre-grazing DM – Post-grazing DM
Total forage consumed = 2700 lb DM/A - 720 lb DM/A = 1980 lb DM/A
Thus during this grazing event 1980 lb DM/A were consumed.

Using Rising Plate Meter

	Pre-grazing	Post-Grazing
Initial plate meter	57893	60245
Final plate meter	58943	60670
Counter	25	25
Final – Initial	58943 - 57893 = 1050	60670 – 60245 = 425
Average RPM	1050/25 = 42	425/25=17
Yield†	42*69 - 560 = 2338 lb DM/A	17*69 - 560 = 613 lb DM/A

†This equation was developed for grass based pastures (less than 30% legumes).

Total forage consumed = Pre-grazing DM – Post-grazing DM
Total forage consumed = 2338 lb DM/A - 613 lb DM/A = 1725 lb DM/A
Thus during this grazing event 1725 lb DM/A were consumed.