Absorption of Nitrogen, Phosphorus, and Potassium from Nutrient Sprays by Leaves

SUMMARY Barley, Brussels sprout, French bean, tomato, and sugar-beet plants grown in soil in pots and sprayed, usually daily, for several weeks, with nutrient solutions containing nitrogen, phosphorus, potassium, and a spreader, with precautions to prevent the spray solution falling on the soil, had higher nutrient contents and dry weights than control plants sprayed with water and spreader only. Increase in nutrient content occurred with high or low levels of nutrient supply to the roots and was approximately proportional to the concentration of spray and to the frequency of spraying. The nitrogen content of sugar-beet plants was increased equally by spraying with solutions supplying ammonium sulphate, calcium nitrate, or urea in equiva lent concentrations. Nutrient uptake from solutions sprayed on leaves influenced uptake by the roots so that the additional amounts of nutrient contained in sprayed plants may be greater or smaller than the amount absorbed from the spray by the leaves.