水稻根际硝化─反硝化作用生态因子的水平空间变异

采用根际模拟和切片技术研究水稻根区土壤硝化－反硝化作用及其相关生态因子沿根系接触面水平空间变异的结果表明，土壤潜在硝化作用强度和反硝化作用强度随距极系接触面距离的增加而降低；由于硝化细菌是严格的好氧微生物，土壤潜在硝化强度随距根系接触面水平距离急剧减弱，而潜在反硝化强度则变弱趋势较为缓和；土壤０．５ｍｏｌ／ＬＫ２ＳＯ４可提取碳及其碳氮比随距根系接触面距离增大而下降，土壤速效氮则反之；土壤亚硝酸Ｋ２

HORIZONTAL SPATIAL VARIATIONS OF ECOLOGICAL FACTORS OF NITRIFICATION-DENITRIFICATION IN SOIL OF RICE RHIZOSPHERE

Horizontal spatial variations of nitrification-denitrification in soil and its ecological factors in the soil of rice rhizosphere were determined by the eco-modeling technique and cutting method.Results indicated that the potential nitrification and denitrification intensities in soils decreased with increase in distance from the rice root interface.The potential nitrification intensity in soil dropped down sharply with increase in distance, but the potential denitri6cation intensity changed moderately, because the nitrifying bacteria are strict aerobic-autotrophic microorganisms and the denitrifying bacteria are facultative anaerobes.The amount of available carbon in soil and the ratio of that to the amount of available nitrogen reduced with increase in distance from the root interface, but the amount of available nitrogen increased.The amount of nitrosofying bacteria was larger in the zones of 10-20mm and 20-30mm from the root interface than that of 0-10mm due to the competitive absorption of nitrogen.