El- Sayed, G. A. M. ; S.M. Ahmed and O.A.O. Mazen( 2009). Microbial Population and Enzyme Activity in Sandy Soil Influenced With Nitrogen Sources, Rates and moisture Levels.Egypt. J of Appl. Sci., 24 (6A)2009 382-392
Abstract: To study the effect of different nitrogen source (i .e. ,aqua ammonia 20 % N, urea 46 % N, ammonium sulphate 20.6 % N and Compost 1.63 % N,38.50 %OM ) application with different rates (i.e. 0, 40 , 80 and 120 ppm N) under different levels of soil moisture content (i. e. 30 ,60 and 90 % of water holding capacity(W.H.C.) ) and their combinations in sandy soil on total count bacteria and nitrifying bacteria, dehydrogenase and urease activity. The soil samples were then incubated for 28 days at 30 oC. These parameters were evaluated at different intervals of 1, 2, 3, 7, 14, 21 and 28 days.
The main results of this study can be summarized as follows: 1- The maximum values of total count bacteria, nitrifying bacteria, dehydrogenase and urease activities were obtained due to the application of compost compared to the other applied nitrogen sources.
2- Except the urease activity, the total count bacteria, nitrifying bacteria and dehydrogenase activity were increased by increasing the nitrogen rates.
3- The highest and lowest values of total count bacteria, nitrifying bacteria, dehydrogenase and urease activities were recorded at 60 % of W.H.C. and 90 % W.H.C., respectively.
4 – The maximum values of total count bacteria, nitrifying bacteria, dehydrogenase and urease activities were achieved at 14 days from incubation.
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