An article by Agroscope

Estimating Herbage Mass to Make Optimal Use of Pastures

Grazing dairy cows is a characteristic feature of Swiss agriculture. In order to use pasture efficiently, the estimation of herbage mass is recommended. Agroscope compared two methods and developed estimation formulas for implementation in practice

Grazing generally improves animal welfare, and the consumption of fresh grass can have a positive effect on milk composition. For economic reasons, however, pastures should be used as efficiently as possible. This gives rise to the following questions: How much grazing area is needed? How long can a paddock be stocked with cows? In what order should the paddocks be used? Are additional roughage and concentrates necessary as a supplement to pasture herbage, and if so, how much? In order to answer such questions, it is helpful to know how much forage the pasture yields.

A Comparison of Two Measuring Devices

In this study, two methods measuring pasture height in different ways were compared: the rising plate meter compacts the sward with its circular plate, whilst the pasture meter measures sward surface height with the aid of light beams.

Detailed measurements were carried out with both devices at two sites (Posieux and Sorens) and during different seasons over a five-year period. According to the analysis of the results, both devices are equally good at estimating herbage mass, although the estimation error is high.

Influence of Site and Season

Estimation formulas were developed for use in farming practice. If these formulas were additionally differentiated according to site or season, the accuracy of the herbage mass estimate was improved. Because the botanical composition of the pastures had no significant effect, however, differentiated formulas for individual plant communities were not developed.

Finally, it should be borne in mind that the pasture meter is easier to use, but is significantly more expensive than the rising plate meter.

Conclusions

  • Unlike the pasture meter, the rising plate meter compresses the sward surface height, which yields different measurements. Formulas for estimating herbage mass were therefore developed for both devices for use in farming practice. In addition, conversion formulas are provided to allow the comparison of sward heights and recommended values.
  • Both devices are equally good at estimating herbage mass; however, the estimation error is high.
  • Farm-specific formulas as well as the inclusion of the season improved the accuracy of the estimate.

Scientific article

Estimating Herbage Mass to Make Optimal Use of Pastures

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