Nitrate and Ammonium as Sources of Nitrogen for Corn and Their Influence on the Uptake of Other Ions1

Abstract No yield differences in tops or roots were measured between ammonium and nitrate nitrogen sources in flow ‘United 108’ grown for 14 or 28 days in constant flow culture solution. There was a greater uptake of N from the nitrate source but approximately 25% of the total uptake remained as nitrate within the plant. Higher plant levels of phosphorus and sulphur were measured in the ammonium treatment and higher Ca++ and Mg++ in the nitrate treatment indicating a predominately cation‐anion balance effect.