The number of culturable nitrifying and denitrification bacteria, ammonifiers bacteria and azotobacteria in a sample was determined by counting colony forming units (CFU).
At the early and late rice main growth stages, the numbers of soil ammonifiers bacteria decreased as follows: MF>RF>LOM>HOM>CK.
In the present study, the results indicated that different fertilization managements were significantly affected some physiological function soil microbial quantity, including the soil nitrifying and denitrification, ammonifiers, cellulose-decomposing and azotobacteria bacteria.
Meanwhile, the communities and activities of soil physiological function bacterial (nitrifying and denitrification, ammonifiers, cellulose-decomposing and azotobacteria bacteria) were affected by the soil physicochemical properties [7,8], fertilizer regimes [9, 34], type of crops and planting systems , and the fertilizer managements is an important factor for affect the communities of soil bacterial.
At the early and late rice main growth stages, the numbers of soil nitrifying and denitrification bacteria higher in HOM treatment, and the numbers of soil ammonifiers bacteria higher in MF treatment, the numbers of soil cellulose-decomposing bacteria higher in LOM treatment, the numbers of soil azotobacteria bacteria higher in RF treatment, respectively.
Data obtained from the studies show that the population of ammonifiers varies considerably for different experimental plots and depends on the quality of incoming plant residues of the previous crop (Figure 1).
Their lowest amount is observed in winter wheat monoculture (19.8 x [10.sup.6] cells/g) and maize for silage (12.3 x [10.sup.6] cells/g); in peas and oats mixture, the population of ammonifiers increases (25.4 x [10.sup.6] cells/g), as well as in peas (35.6 x [10.sup.6] cells/g).
The changes in the population of microorganisms that use mineral forms of nitrogen (KAA medium) containing overwhelming population of nitrifiers are similar to ammonifiers, with the only difference that their population is somewhat more than that for the ammonifiers.
According to the obtained data, the population of ammonifiers differs depending on the previous crop: for maize and silage, it varies from 12.8 to 18.8 x [10.sup.6] cells/g depending on the soil tillage method and for seeded fallow--from 18.7 to 22.3 x [10.sup.6] cells/g.
In the course of their decomposition and transformation into the accessible forms, an active role is played by groups of microorganisms, such as the ammonifiers, cellulose-decomposing microorganisms, and microorganisms, that use mineral nitrogen for their nutrition.
Studies have shown that deepening of the arable layer of the soil, by both plowing and combined tillage, lead to an increase in the population of ammonifiers and microorganisms that use mineral forms of nitrogen; at the same time, conducting these treatments did not cause activation of cellulose-digesting microorganisms that indicates the lack of enhancement of the mobilization processes, probably, due to diversity in quality of soil layers.
A higher mancozeb concentration seems to be persistent in its toxicity towards ammonifiers
. Dubey and Rodriguez  reported nonpersistent effect of ethylene-bis-dithiocarbamate on ammonification in acid laterite, clay, and alluvial soil.