Sampling Horse Pasture for AnalysisBy Kentucky Equine Research Staff · October 23, 2014
The key to accurate pasture analysis is sampling multiple grazing sites. For best results, randomly select 12 to 20 sites where horses have been grazing and clip a handful of forage at grazing height. Grazing height is the level to which the animals are consuming. For example, if the grass is 25 cm (10 in) high and the animals are consuming the top 15 cm (6 in), it is only the top 15 cm that should be submitted for analysis.
All subsamples should be combined and thoroughly mixed in a clean plastic bucket to form a composite. Cutting the forage into pieces about 5 to 8 cm (2 to 3 in) long aids in blending. Take a 0.5 kg (1 lb) sample, pack it tightly in a plastic bag, seal, and freeze it for 12 hours prior to submission. Freezing will help prevent marked chemical changes due to respiration or fermentation.
It is also important to remember that pasture foliage is wet. This may seem obvious, but not many people realize its significance. For example, pasture grass is typically about 20% dry matter. A 500-gram sample submitted for analysis will be split and half will be used for analysis. Upon drying the 250-gram split sample, 50 grams will be left. After grinding, 45 grams will be left for analysis, or less than 10% of the original weight. Thus, it is important to take into account the moisture level of the sample prior to submission to insure that the lab has an adequate amount of material for analysis. The wetter the sample, the greater the amount of sample required.
Samples will arrive at the laboratory in the best condition if they are frozen or dried prior to submission. Dried samples are also less expensive to ship. Laboratories can offer suggestions on how to dry the samples.
Following simple collection procedures will ensure the most accurate results from pasture analysis.