Calcium Leaching to Increase Rooting Depth in a Brazilian Savannah Oxisol1
- K. Dale Ritchey,
- Djalma M. G. Souza,
- Edson Lobato and
- Osni Correa2
Root growth in subsoils of Oxisols is often precluded because the roots of many crops are sensitive to soil acidity. This increases plant stress during dry periods when available soil water in the limed surface layers is exhausted. The low soil CEC and high rainfall in Central Brazil suggest that soluble calcium salts might leach below the plow layer and reduce soil acidity. To test this possibility, soil columns, simulating field profiles, were constructed in the laboratory and various Ca salts were mixed in the 0 to 15-cm layer. Addition of 1,200 mm water to 2,000 kg/ha Ca added as CaCl2, CaSO4, and CaCO8 caused Ca movement to 180, 75, and 25 an, respectively. Calcium sulfate decreased Al saturation and maeased soil pH at depth.
Several field experiments were sampled to determine the effect of previous treatments on the movement of Ca + Mg. Three to four years after application of gypsum, in ordinary superphosphate, subsoil pH and Ca + Mg status were increased, and Al saturation decreased at depths as p a t as 75 to 90 an. Zeta mays L. roots growing in the improved subsoil environment were able to take up water and withstand droughts.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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