原状土就地培养取样法定位研究田间土壤氮动态变化

Application of in-situ technique at field to study the N dynamic of soils

本文介绍了原状土就地培养取样技术的原理及方法应用,并对森林破坏后的次生演替、人工林种植和农业耕作等不同方式下氮素营养在时间进程及空间结构上的动态变化过程进行定位监测研究。结果表明,原状土就地培养取样法结构简单,方便易行,对土壤几乎没有扰动,也没有区域土壤类型的限制,弥补了其他方法的不足和研究的单一性,可定量化监测不同利用类型土壤氮库动态变化中的氮释放与固定、吸收和淋失等氮素营养随时间和季节变化的整个过程以及人为活动干扰后土壤氮营养的空间变异,为田间条件下土壤氮库动态变化定位研究的有效方法。

A methodology for studying dynamic of mineral N of soils in field based on sequential soil coring and in situ exposure of largely undisturbed soil columns confined within metal tubes is described. The method is evaluated through the N spatial changes in different utilization types from time t to time t+1 and t+2. The results show that the sequential measurement of changes in the amount of soil mineral N in confined (no N uptake by roots) and unconfined soils allows rates of net N mineralization (or immobilization), plant uptake N, and maximum N leaching to be calculated. It causes fewer disturbances to natural processes and can be applied to any soils, and it provides reliable quantitative estimates of dynamic of mineral N of soils in field. It also can be used to study the effects of human disturbances on soil mineral N. The results show that human disturbance can either increase net N mineralization, cause leaching of N and immobilization of N, alter the proportion of nitrate nitrogen produced during incubation, or induce or obscure the effects of previous fertilization on rates of N mineralization.