Rate of intake, accumulation, and transformation of nitrate nitrogen by small grains and Kentucky bluegrass
1930
McCool, M.M. | Cook, R.L.
It appears logical to draw the following conclusions from these studies: The intake by plants of nitrogen added to the soil is very rapid, showing up in the expressed sap in 15 hours after treatment. Changes in the concentration of nitrate nitrogen in the soil are usually accompanied by proportional changes in the expressed sap of the crop. Sodium nitrate causes a quicker and greater increase in the nitrate content of the expressed sap than do either ammonium sulfate, urea, or ammonium phosphate. The rate of transformation of nitrate nitrogen in the plant is very rapid, as indicated by a considerable decrease in the nitrate content of the expressed sap of plants three hours after the source of nitrate supply was removed. Wheat plants grown in sand cultures did not attain maximum growth, although some of the cultures contained as much as 20 p.p.m. of nitrate. In general, an increase of nitrate nitrogen in the sand cultures was accompanied by increased growth, an increase in the concentration of nitrate nitrogen, and a decrease in the concentration of phosphorus in the expressed sap of the plants.
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