Effects Of Decomposing Substrate Quality On The Dynamics Of Nitrogen Mineralization In Forest Soils

The assessment of forest ecosystem manipulating function could be improved by the study of the interaction of soil organic carbon and nitrogen under the scenario of the global change. This study was carried out in Taiyue mountain of Shanxi province. The inorganic nitrogen content of Pinus tabuliformis soil was monitored via the method of original site tube incubation after the additions of broadleaf detritus(BD),needle detritus(ND), stem wood detritus (SD)and biochar (B)with equal weight into top soils. The study using randomized complete block design,and thirty-five 2m×2m samples were set up.Afer data analysis,the results indicated that 1)The effect of adding different carbon to soil organic carbon was not significant, and the effect of soil total nitrogen content and pH value was not significant either.2)Adding biochar, leaves detritus and wood made the variation of microbial biomass nitrogen and microbial activity:22.07-128.15mg/kg 0.8-3.75mg/kg/d and between different treatments had no significant difference.soil microbial biomass nitrogen content was significantly reduced by the input of biochar and adding wood detritus can significantly increased microbial activity.3)The amount of mineralized soil nitrogen was markedly increased by the inputs of organic matter and 1.29 mg/kg,0.40 mg/kg,-3.47 mg/kg separately for biochar input, leaf detritus input and stem wood detritus input, compared to that of control plot at -20.74 mg/kg; and that the soil nitrogen mineralization rate was simultaneously raised by the additions of biochar and stem wood detritus during the whole experimental period. Overall, this study demonstrated that the nitrogen mineralization was indeed impacted by inputs of organic matter to top soil of Pinus tabuliformis forest, and that its determination magnitude varied with the organic matter quality.4)Different forms of organic carbon addition can change the content of inorganic nitrogen and nitrification and ammonification rate,in October 2014 -August 2015, nitrate nitrogen content of five kinds of treatment increased with time,and it showed May>March>October,but it fell on August 2015. Ammonium nitrogen content was highest in March 2015, the lowest in August 2015. The differences between the treatments were not significant.