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

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.