Soil is the main nitrogen (N) provider for plants but N in soil is not all available to advanced plants. Mineralization is a critical biological process for transferring organic N to inorganic N that can be used by plants directly. To investigate the effect of different levels of soil temperature and water content to soil mineralization, a field experiment was established on three different sites (A, B and C). We measured soil temperature, moisture and electrical conductivity once daily after swine slurry application. Average soil moisture and temperature in site A is the highest among three sites (40.9% and 9.7°C, respectively). Following is in site C (37.3% and 9.6°C) and the lowest is in site B (28.0% and 9.0°C). Ammonium N (NH4+-N) and nitrate N (NO3--N) were determined on the first and fifth day after treatment. Compared with site B and C, site A always had the highest soil total N content (1.54 g N kg-1 on day one; 1.22 g N kg-1 on day five) and highest NO3-- N content (93.18 mg N kg-1 on day one; 16.22 mg N kg-1 on day five) and a significant decrease on day five. Content of NH4+-N in site B and C reduced while in site A, it increased by 6.7%. Results revealed that net N mineralization positively correlated with soil temperature (P<0.5, r=0.675*) and moisture (P<0.01, r=0.770**), suggesting that to some extent, higher soil moisture and temperature contribute more to inorganic N that can be used by plants.

In order to compare greenhouse gases emission from different animal manures and to explore how different animal manures effect on soil mineralization, three kinds of materials, cattle, goat and chicken manure were amended to soil for 14 days incubation as CtS (cattle manure-amended soil), GS (goat manure-amended soil) and ChS (chicken manure-amended soil). Cumulative NH3 emissions in all treatments were rapidly increased until day 7 and then it was slightly increased in three manure-amended soils but maintained in control until day 14. GS had the highest NH3 emission at 0.14 mg kg-1 during the entire experimental period. Emissions of CO2 were highly increased by 7.8-, 9.0- and 12.4-fold in CtS, GS and ChS, respectively, compared to control at day 14. A significant increase of N2O emission in all treatments occurred within 5 days and then it was slightly increased until day 14. N2O emission was 2-fold higher in all manure-amended soils than that of control. Compared to day 1, inorganic N (NH4 + plus NO3 --N) content was highly increased in all four treatments at day 14. The increase rate was the highest in CtS treatment. Net N mineralization was increased by 4.0-, 2.4- and 2.9-fold in CtS, GS and ChS, respectively, compared to control. These results indicate that increase of NH3, CO2 and N2O gas emissions was positively related to high N mineralization.

Mineralization is an important biological process for conversion of organic nitrogen (N) to inorganic N which can be used by plants directly. To investigate the effect of different manures on soil mineralization, the soil amended with cattle (CtM), goat (GM), chicken manure (ChM) and pig slurry (PS) were incubated under in vitro condition and ammonium N (NH4 +-N), ammonification rate and ammonia emission were determined for eighty-four days. NH4 +-N was the highest in PS-amended soil for the whole experimental period. NH4 +-N in PS-amended soil was gradually decreased until day 84, whereas it was rapidly decreased for the first 14 days and then slightly increased until 84 days in ChM-, CtM- and GM-amended soil. The ammonification rate showed negative value for the first 14 days in all treatments. From day 14, ammonification rate started to increase in CtM- and ChM-amended soil, whereas it was maintained in GM- and PS-amended soil until day 84. The daily ammonia emission was the highest in PS-amended soil (41mg kg-1 d-1), followed by CtM-, ChM-, and GM-amended soil at day 1. It was gradually decreased until day 84 in all treatments. The total NH3 emission was the highest in PS-amended soil with 0.6 mg kg-1 for 84 days, while less than 0.1 mg kg-1 in three other plots. These results indicate that different manures showed different soil ammonification rate and NH3 emission.