The effects of selected nitrogen and sulfur applications on soil pH, water soluble sulfate, DTPA extractable iron, manganese, copper and zinc on selected Arizona soils

Abstract

This study consisted of two experiments to determine the effects of selected N and S application on soil pH, water soluble sulfate and DTPA extractable Fe, Mn, Cu and Zn on selected Arizona soils. The soils in the second experiment were incubated at or beyond saturation. Iron and Mn showed significant reduction; Cu and Zn were generaly unaffected. The soil pH remained fairly near neutral and S was not readily converted to SO₄⁻². The soils in the second experiment were drier and in addition were subjected to repeated N and S applications. Soils with low buffering capacities tended to become acidic and have significant amounts of Fe and Mn. Sulfur was more readily converted to SO₄⁻² under drier conditions. Copper and Zn were generally unaffected. Lime (CaCO₃) as a correction measure for soil acidity and excessive Mn was also studied. Additions of lime kept or raised the soil pH to near neutral and significantly lowered extractable Mn.