Effect of Bentonite, Nitrogen Source and Stage of Maturity on Nitrogen Redistribution in Corn Silage

Abstract

Redistribution of nitrogen, when isonitrogenous levels of urea (.5%) or diammonium phosphate (1.1%) were added with 0, .125, .25, .5 and 1.0% sodium bentonite to whole corn plants at ensiling, was studied in 33 pilot silos in Experiment I. In Experiment II, redistribution of 15N urea added to corn plant tissue harvested at 28.8 (low dry matter), 36.4 (medium dry matter) and 49.0% (high dry matter) dry matter was studied. Bentonite was added at 0, .25, .5 and 1.0% to the medium dry matter material. All treatments were ensiled in pilot silos designed to permit collection of gas and seepage fractions.In general, increasing bentonite produced the following changes: increased pH (P<.05), organic acid production (P<.05), incorporation of 15N urea into microbial protein; decreased (P<.05) free α-amino-N and eliminated seepage. Diammonium phosphate-treated samples were higher (P<.05) than urea samples in pH, organic acids, and ammonia N. Recovery of intact urea was greater (P<.05) in medium dry matter samples (79.6%) compared with the low and high dry matter samples (43.2 and 44.8%). Nearly 50% of the 15N urea recovered in high dry matter samples existed as 15N ammonia.Of the total ensiled nitrogen, 11.2% was lost in seepage from low dry matter samples. This accounted for 17.7% of the original 15N urea added. Nitrogen-15-analysis of the gas indicated no 15N urea was lost as volatilized ammonia.