Effect of Urea Application Amount on Microbes and Enzymes in Soil

Effect of different amounts of fertilizer on soil biological process is one of the important issues in soil ecology. In Laboratory, simulating experiment was carried out to study effect of different amounts of urea on numbers of microbe and enzymes activity in a fluvo-aquic soil. The results indicated that actinomycetes and mold were sensitive to urea fertilization, and they decreased by 45.5% and 32.2% in the B(fertilizer:soil=1:1500, w/w) treatment than in the A(without fertilizer application) treatment, respectively. Nitrobacteria had the best growth in the D (1:400) treatment, but they decreased with increasing urea application. Denitrobacteria number always decreased with increasing urea application. Activity of urease, neutral phosphatase and invertase significantly decreased in the E (1:200) treatment.