Effect of Tillage on the Distribution of Manganese, Copper, Iron, and Zinc in Soil Fractions
1985
Shuman, L. M. | Hargrove, W. L.
The availability of micronutrients is affected by soil properties such as pH, organic matter content, and clay mineralogy. Some of these properties can be altered by tillage. Therefore, a study was conducted to determine the influence of tillage on the distribution of Mn, Cu, Fe, and Zn among soil fractions. Soil samples were taken at the 0 to 2 cm depth from a long-term (8 yr) tillage experiment. The treatments were no-tillage, minimum tillage (fall tillage only), and conventional tillage (spring and fall tillage). Soil samples were fractionated sequentially to determine Mn, Cu, Fe, and Zn in the following fractions: exchangeable, organic, Mn oxide, amorphous Fe oxide, crystalline Fe oxide, and residual. Double acid-extractable P and Zn, organic matter content, and cation exchange capacity were higher in no-tillage treatments than in the other tillage treatments. Tillage had more effect on the distribution of Mn and Fe among fractions than on the distribution of Zn and Cu. No-tillage lowered the Mn in the exchangeable and amorphous Fe oxide fractions and raised Mn in the organic fraction compared to minimum tillage or conventional tillage. Iron in the exchangeable and organic fractions was higher for no-tillage, while amorphous oxide Fe and residual Fe were lower for no-tillage compared to conventional tillage. Both Mn and Fe appeared to be shifted by no-tillage from the oxide and residual forms into the more plant-available exchangeable or organic forms.
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