
%0 Journal Article
%A Yadav, DS 
%A Kumar, V 
%A Singh, M 
%A Relan, PS 
%T Effect of temperature and moisture on kinetics of urea hydrolysis and nitrification
%J Soil Research
%D 1987/06/01
%V 25
%N 2
%P 185-191
%K 
%R https://doi.org/10.1071/SR9870185
%U https://www.publish.csiro.au/paper/SR9870185 
%X The effects of temperature and moisture regimes on kinetics of urea hydrolysis in soils of Hisar (Typic Camborthids) and Hansi (Typic Ustochrepts) were studied. The rate constant (K) for first-order reaction increased with temperature from 10 to 35°C. Energy of activation (Ea), activation free energy (ÄF*) and activation entropy (ÄS*) between 10 and 35°C were 33.8, 81.8 kJ mol-1 and -176.55 K-1I in a sandy loam soil, and 29.2, 81 -6 kJ mol-I and - 155.3 J K-I in a clay loam soil, respectively. The hydrolysis rate was not a linear function of moisture content but increased with field capacity (F.C.). The rate of hydrolysis in both the soils followed the order: 20% F.C. < 40% F.C. < 80% F.C. = 100% F.C. The rate for flooded soil was between those for 20% and 40% F.C. for sandy loam, and between 40 and 80% F.C. for the clay loam. The added urea was completely hydrolysed in 3 days at all moisture regimes except 20% F.C.; maximum NH4+-N was found at the third day, then decreased thereafter. The time at which NO2- first appeared varied with treatments, but then it persisted throughout the 24-day incubation in all treatments. 
