Abstract: In the development process of soil testing for trace elements, the test techniques are being improved, abilites of soil in applying available trace elements are revealed more thoro ughly, and positive roles of soil testing in fertilization and protection of ecological en vironment are played more obviously.Recently, the test means adopted widely are AAand ICP, but photometry and polarography still occupy a certain position in soil test of trace elements, because of their handy equipments and the improvement of their sensitivity and accuracy. Available trace elements in soils are mainly extracted by selected extractants, techniques for directly extracting soil solution are improved, and hence, it may be possible to easily determine the level of trace elements in soil solution. Critical values or criteria may be evaluated by various methods and act as a bridge in the application of test values. The author adopts the criteria to grade test values of soil available trace elements in Taching and make maps, so as to ascertain the deficiency area and fertilizer-demand regions.Then, effects of fertilization and economic benefit may be forecasted by means of functional relation between level of available trace element and yield increase percentage.

Key words: Trace elements, Soil test, Evalution criteria