THE EFFECT OF NITROGEN FORM AND SOIL TEMPERATURE ON THE GROWTH AND PHOSPHORUS UPTAKE OF CORN PLANTS GROWN IN THE GREENHOUSE

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Abstract
In a greenhouse experiment, corn seedlings were grown over a 2-week period in soil and in sand-resin media. Nitrate and ammonium nitrogen was applied at rates from 25 to 800 p.p.m., and phosphorus at 50 and 200 p.p.m. Soil temperatures of 60°, 70°, and 80 °F. were used.It was concluded that growth and phosphorus uptake reached a maximum when approximately 200 p.p.m nitrogen was applied. Total dry matter production in roots was inversely related to nitrogen application, and to total phosphorus uptake. In soil, the ammonium form of nitrogen tended to be more effective than the nitrate form in increasing phosphorus uptake. In sand-resin with an absence of nitrification, the opposite was found. Significant interactions were found between nitrogen rate and form. Increasing soil temperature from 60° to 80 ° F. enhanced the effect of nitrogen on phosphorus uptake.