LIMING OF TWO ACIDIC SOILS IMPROVED GRASS TETANY RATIO OF STOCKPILED TALL FESCUE WITHOUT INCREASING PLANT AVAILABLE PHOSPHORUS

Abstract

Abstract Previous research demonstrated that phosphorus (P) fertilization of tall fescue (Festuca arundinacea Schreb.) pastures on acidic soils increased leaf P, magnesium (Mg), and calcium (Ca) concentrations and reduced the risk of grass tetany. It has been suggested that liming could have a similar effect by increasing soil pH and remobilizing sorbed P. To investigate this option, calcitic or dolomitic limestone was applied to stockpiled tall fescue plots on two acidic soils, a fragipan and a claypan. As expected, increasing rates of limestone were correlated with higher soil pHs. Contrary to predictions, limestone applications had very little effect on soil or plant P. However, both types of limestone at both locations altered leaf macronutrient concentrations in a manner that improved the grass tetany equivalent ratio: increased Ca and/or Mg and decreased K concentrations, thus lowered the likelihood of grass tetany in grazing beef cattle. Keywords: tall fescuestockpiledgrass tetanyphosphoruslimingcalciticdolomitic ACKNOWLEDGMENTS This study was supported by the Missouri Fertilizer and Ag Lime Council. The authors thank Dr. Will McClain and Dr. Maru Kering for their assistance with the field experiment, Dr. Rob Kallenbach and Mr. John Couts for their help with the Leco N analysis, and Dr. Mark Ellersieck for his help in statistical analysis.