عنوان مقاله [English]
Regard to importance of organic manures application in agriculture, this research was carried out to study the amounts of nitrogen mineralization from organic manures as a completely randomized design with factorial experiment and 3 replications. Amounts of mineralized nitrogen in four organic manures (i.e. sewage sludge, poultry manure, cattle manure, and wheat straw) at two levels of moisture including low (40 % of field capacity) and high (75 % of field capacity) were measured during 10 days intervals for two months. The cumulative amounts of mineralized ammonium (NH4+) and nitrate (NO3-) was measured by spectrophotometer method. The results showed that the mineralized NH4+ decreased during the studied period. The type of manure, moisture, and the time caused to significant difference in mineralization of NO3-. Also, the interaction effects of manure-time, and time-moisture were significant on mineralized NO3-. The highest mineralized nitrogen (NH4+ and NO3-) was found in poultry manure treatment (269.7 mg kg-1). The trend of mineralization was poultry manure > cattle manure > sewage sludge > wheat straw. By increasing the moisture from 40 to 75 % of filed capacity, the amounts of mineralized nitrogen was increased 36, 9, 6, and 86 percent in poultry manure, sewage sludge, cattle manure, and wheat straw, respectively. Therefore, due to improving soil physical properties and the availability of some nutrition requirement for plants, application the organic manures especially poultry manure is recommended.