Seasonal Effects of Nitrogen Fertilization on Three Species of South Texas Browse Plants

Abstract

We conducted a study in Kenedy County of south Texas to determine nitrogen (N) fertilization effects on crude protein (CP), P, Ca, K, and Mg contents of 3 important deer browse plants (granjeno, Celtis pallida; lime pricklyash, Zanthoxylum fagara; and bluewood, Condalia hookeri). Four N fertilizer rates (56, 112, 168, and 224 kg N/ha) were applied in February 1980 to improved rangeland plots where brush was reinfesting. Control plots were nonfertilized. Vegetation samples were assayed for CP, P, Ca, K, and Mg contents on 5 dates: June, September, and December 1980, and April and July 1981. The CP content of plants fertilized with 112 kg N/ha or more was significantly higher (P = 0.05) than those fertilized with 56 kg N/ha or nonfertilized. Except for lime pricklyash plants fertilized with 224 kg N/ha, the CP content of plants fertilized with 168 and 224 kg N/ha was not significantly different from those fertilized with 112 kg N/ha. The addition of 56 kg N/ha had no effect on the species' CP content. Nitrogen fertilization had little effect on the P, Ca, K, and Mg contents of the species. The 3 species from both nontreated and treated plots had adequate CP, Ca, K, and Mg levels for deer nutritive requirements throughout the study, but P levels were generally deficient except in April 1981.