Evaluation of the Forage-Disk Method in Mixed-Grass Rangelands of Kansas

Abstract

The forage disk meter, a double sampling device used to predict forage biomass, has been used extensively on improved pastures, but its use on rangelands has not been investigated thoroughly. Efficiency of the forge d&k meter was investigated in predicting yields of forage biomass on different range sites in western Kansas. Using le8st sqtmres regression methods, resting heights (forage buik) and dry matter yields were used to calibrate the disk meter for eachsiteands8mplingd8te.HighiysignKiantregressiom(F<0.ooo1) were obtained on l U tbe shortgrass sites, where several factors that had unfavorable effects on the regression relationship between fornge bulk and forage biomass were not apparent. These factors, although not quantified, included l ccumul8tion of litter, microrelief, lodged vegetation, and presence of broadleaf species. Regression coeffkients (b) and intercepts (a) varied between sites and dates, thus the forage disk meter should be calibrated for every range site. If 8 forage disk meter is calibrated for a specific range site, regression coefficients utd intercepts might not differ from yeu to year if grazing pressure and species composition are temporally consistent, which implies that recalibration might be unnecessary. The forage disk meter was useful as a double sampling device on range sites dominated by sbortgrawes, but its use was limited on areas dominated by mual forbs or midgrasses.