宜兴市稻田表层土壤生物固氮量的空间分异特征

Study on Spatial Characteristics of Biological Nitrogen Fixation of Rice Paddy Soils in Yixing City

通过对水稻土的系统采样,利用乙炔还原法估算宜兴市稻田土壤的生物固氮量;采用地统计学方法,对稻田土壤的生物固氮量空间变异特征进行分析。结果表明:研究区单位面积生物固氮量范围为0.75~46.85 g/m^2,均值8.04 g/m^2。采用普通克里格法对采样数据进行了空间插值,稻田土壤的生物固氮量总体呈带状分布,高值区位于研究区西南和东南方向靠近丘陵地区,低值区则位于研究区西北和东北方向地势平坦的区域。地统计学中的变异系数和块金值均表明稻田土壤的生物固氮量属中等空间变异,即研究区内稻田土壤的生物固氮量受到结构性变异和随机变异的共同影响。可见,人为经营活动与自然环境共同影响着稻田土壤的生物固氮量。

The spatial characteristics of biological nitrogen fixation(BNF)of rice paddy soils in Yixing city was studied using the acetylene reduction method and geostatistics method.Soil samples were collected systemically with a grid of 2 km×2 km.Results showed that BNF rate ranged from 0.75 to 46.85 g/m2 with an average of 8.04 g/m2.The raw data was logarithmically transformed to meet a normal distribution and then an optimized Kriging method was employed to describe the spatial distribution of BNF.BNF showed a belt distribution in the study region.The high value of BNF occurred in the southwest and southeast areas while the low value in northwest and northeast areas of the study region.The variation coefficient and nugget value showed a medium spatial variation of the BNF.Generally,BNF of paddy soils was influenced simultaneously by the artificial management and natural condition.