Nutritive Value of Forages on Sandy Soils As Affected by Tebuthiuron

Abstract

Tebuthiuron, [N-(5-1,1-dimethyethyl-l1,3,4-thiadiazol-2-yl)-N,N′-dimethylurea], a root-absorbed pelleted herbicide, was broadcast onto sand shinnery oak (Quercus havardii) rangeland in west Texas, May 1978. Green herbage of the dominant grasses was assayed for nitrogen (N), phosphorus (P), 24-hr in vitro dry matter digestibility (24 hr-IVDMD), and cell wall content (CWC) on 3 dates in both 1978 and 1979. In 1978, tebuthiuron at 0.4 kg/ha or above improved quality of the major forages. Crude protein was up to 28% higher in treated plants the year of application. The P content ranged from 0.08 to 0.12% over all sampling dates. Digestibility increased slightly while no difference was found in CWC. Tebuthiuron had no effect on forage quality the year after application. The most consistent change in parameters measured was water content of little bluestem (Schizachyrium scoparium). Untreated plants averaged 38% water throughout the growing season, while treated plants contained 50% water. Major benefits of killing oak are increased forage availability and not yet resolved palatability factors.