The effect of three years cropping (1982 to 1985) under no-tillage and conventional tillage on the DTPA-TEA extractable zinc, copper, manganese, and iron content of a clayey and a medium-textured Red-Yellow Latosols from São Paulo State, Brazil, were studied. The sites were sampled at five depths (0-5 cm, 5-10 cm, 10-20 cm, 20-30 cm, and 30-50 cm) with twelve replications per treatment. Increasing the depth, a significant decrease in the levels of zinc and manganese, in both soils, and of iron in the clayey Red Yelow-Latosol, was observed. Variations in the concentration of zinc, manganese, and iron were highly correlated with the soil organic matter content. The levels of copper and manganese were affected by the tillage system in the clayey Red-Yellow Latosol: both elements were higher in the no-tillage treatment. On the other hand, the tillage system did not affect the concentration of zinc and iron in the soils studied.
soil micronutrients; no-tillage; soil management