DETERMINATION OF BOTANICAL COMPOSITION OF TWO-COMPONENT FORAGE MIXTURES

Abstract

A comparative study was made in 1958 of the visual estimation and hand separation methods of determining botanical composition of two-component forage mixtures. The results indicated that there were positive significant correlations between the per cent legume values obtained by the two methods. The visual estimation method was less variable than the hand separation method and the precision per unit cost was greater. The differences between per cent legume values obtained by the two methods were influenced by the stage of maturity (medium or late hay) of the components and the cut (hay or aftermath). In this study, the difference was significant only in the medium aftermath cut.Individually, three observers showed some inconsistencies between estimates on the medium and late maturity groups and between the hay and aftermath cut. However, by averaging the three estimates to obtain a mean sample, these inconsistencies were minimized.Both methods were more precise in the aftermath pasture cut than in the hay. An additional observer increased precision of the visual estimate more than an additional replicate or sample. The greater precision resulting from additional replicates, samples, or observers increased at a decreasing rate. The number of replicates, samples, and observers required for specific degrees of precision and a specific cost were calculated.The experiment showed that the visual estimation method can be superior to the hand separation method as a means of determining botanical composition.