土壤微生物体氮的季节性变化及其与土壤水分和温度的关系

以杨陵土垫旱耕人为土(中等肥力红油土)为供试土壤进行田间试验和室内培养试验,研究土壤微生物体氮的动态变化及其土壤含水量和温度的关系。结果表明,田间土壤微生物体氮的变化有明显的季节性;夏季最高,冬季最低,其它时期居中;且与土壤温度有显著或极显著的正相关性,相关系数在0.855以上;试验期间土壤水分含量在10%以上,基本能满足微生物活动所需,因而微生物体氮的变化与水分关系并不密切。应用培养试验结果进一步证明了田间试验结果,即在4～36℃范围内,微生物体氮与温度呈线性相关,而在土壤含水量为6.75%～23.23%范围内,与水分呈指数相关关系,当土壤水分小于10.87%时,水分对微生物体氮有突出结果,当超过10.87%后,几乎没有影响。频繁的干湿交替会使微生物体氮显著减少,但冻融交替却无明显影响。

Seasonal change of soil microbial biomass and the relationship between soil microbial biomass and soil moisture and temperature

Field and incubation experiments were conducted with eumorthic anthrosols to study the dynamic change of soil microbial biomass nitrogen as well as the influence of soil moisture and temperature.Field trial showed that soil microbial biomass nitrogen was the highest in summer and hiher in spring and autumn,where as middle at the beginning of winter and lowest in the hard period of winter,and there existed very significant of significant positive correlation between microbial biomass nitrogen and soil temperature,the correlation coefficient of which was over 0.855.In the period of field experiment,the soil water content was enough for microorganism activity,so there was no relationship between microbial biomass nitrogen and soil water.The results of incubation experiment revealed that in the range from 4℃ to 36℃,the soil microbial biomass nitrogen increased with temperature increase,both of which had a significant linear relationship.It was another story for relation of soil moisture to soil microbial biomass nitrogen:the microbial biomass nitrogen increased with moisture in the range from 6.7% to 11.0% while maintaining stable when soil moisture varied from 10.9% to 23.2%,and the correlation equation between soil microbial biomass nitrogen (B_N) and soil water content 9x) was B_N=74.679e^-0.0588/x(r=0.956^*). The microbial biomass nitrogen decreased dramatically with frequent wettingdrying alternation and hardly changed with freezing-thawing alternation.