Comparison of Four Methods to Estimate the Dissolved Nitrogen Fraction in Range Plants

Abstract

Aboveground biomass of four range species was collected at several phenological stages and total nitrogen was determined. The dissolvable nitrogen fraction within these samples was estimated utilizing four techniques: (1) in vivo nylon bag digestion in a rumen-fistulated Bison bison; (2) in vitro Tilley and Terry plus pepsin; (3) neutral detergent fiber; and (4) laboratory detergent fiber. Total nitrogen concentration in all plant species studied was highest during early growth and decreased with advancing maturity. A similar amount of nitrogen was removed from dead or dormant plant materials using any technique, but significantly more nitrogen was removed from green succulent material utilizing the nylon bag technique than was removed with the three laboratory assays. The amount of nitrogen removed from plant foliage was highly correlated among techniques. Equations were developed to predict nitrogen losses with the nylon bag technique using dissolved nitrogen values obtained from any of the other three techniques.