宜兴市稻田表层土壤生物固氮量的空间分异特征

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。

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

The spatial characteristics of biological nitrogen fixation of rice paddy soils in Yixing city was studied using the acetylene reduction method and geostatistics method. Soil samples were collected in systematic with a grid of 2 km * 2 km. Results showed that the biological nitrogen fixation rate ranged from 0.75 to 46.85 g/m₂ with an average of 8.04 g/m₂. The total amount of biological nitrogen fixation in the region was estimated as 4352-4396 t annually. The raw data was transformed to meet a normal distribution and a optimized Kriging method was employed to describe the spatial distribution of biological nitrogen fixation. The distribution showed a belt shape of the study region. The high value of biological nitrogen fixation occurred in the southwest and southeast part while the low value in northwest and northeast part of the region. The variation coefficient and nugget value showed a medium variation of the biological nitrogen fixation of paddy soils in spatial. Generally, the biological nitrogen fixation of paddy soils was influenced by the artificial cultivation and natural condition together.