水稻根际硝化─反硝化作用生态因子的水平空间变异

HORIZONTAL SPATIAL VARIATIONS OF ECOLOGICALFACTORS OF NITRIFICATIONDENITRIFICATIONIN SOIL OF RICE RHIZOSPHERE

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根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；土壤亚硝酸细菌在距根系接触面１０－２０ｍｍ和２０－３０ｍｍ区分布较高，在根际土壤层因受水稻根系竞争吸收影响反而分布较少。

Horizontal spatial variations of nitrification-denitrification in soil and its ecologicalfactors in the soil of rice rhizosphere were determined by the eco-modeling techniqueand cutting method. Results indicated that the potential nitrification and denitrificationintensities in soils decreased with increase in distance from the rice root interface. Thepotential nitrification intensity in soil dropped down sharply with increase in distance,but the potential denitrification intensity changed moderately, because the nitrifyingbacteria are strict aerobic-autotrophic microorganisms and the denitrifying bacteria arefacultative anaerobes. The amount of available carbon in soil and the ratio of that tothe amount of available nitrogen reduced with increase in distance from the rootinterface, but the amount of available nitrogen increased. The amount of nitrosofyingbacteria was larger in the zones of 10-20mm and 20-30mm from the root interfacethan that of 0-10mm due to the competitive absorption of nitrogen.