A laboratory assessment of various treatment conditions affecting the ammoniation of wheat straw by urea. 1. The effect of temp

Author: S.W.P. Cloete & N.M. Kritzinger
Year: 1984
Issue: 2
Volume: 14
Page: 55 - 58

The effect of temperature, moisture level and treatment period on the ammoniation of wheat straw by 75 9 urea per kg wheat straw was investigated in a 4 x 2 x 6 factorial experiment. Independent variables included temperatures of 4; 14; 24 and 35°C, moisture levels of 250 and 375 g/kg wheat straw and treatment periods of 0; 1; 2; 4; 6 and 8 weeks. Dependent variables investigated were total nitrogen content, urea content, free ammonia nitrogen content and in vitro organic matter digestibility (IVOMD). Temperature, moisture level and treatment period significantly (P 0,01) affected ammonia release from urea. The efficiency of ammoniation was accordingly affected. Slow ammonia release at 4 °C (at both moisture levels) and at 14 °C (only at the lower moisture level) resulted in lesser improvements in IVOMD after a treatment period of eight weeks. Ammoniation was accelerated at higher temperatures, particularly at the higher moisture level. Comparable IVOMD values were obtained after a treatment period of one to two weeks at 35 °C and approximately six weeks at 24 °C. Less ammonia was released from urea at 35 °C and the moisture level of 375 g/kg, possibly owing to a decrease in urease activity at this temperature. Significant (P 0,01) temperature x treatment period and moisture level x treatment period interactions were obtained, indicating that the slow reaction at lower temperatures and at lower moisture levels can partly be compensated for by a longer treatment period.



Keywords: in vitro organic matter digestibility, moisture level, nitrogen content, temperature, treatment period, Urea-ammoniation
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