EFFECT OF SOIL MOISTURE STRESS ON YIELD, WATER-USE EFFICIENCY AND MINERAL COMPOSITION OF OATS AND ALFALFA GROWN AT TWO FERTILITY LEVELS

Abstract

Yields of oats and alfalfa grown in two soils in the greenhouse, with and without fertilizer, usually decreased with increasing moisture stress obtained by depleting the available moisture to 75, 50, 25 and nearly 0 per cent.An application of 6-20-20 fertilizer for oats and of 0-20-20 for alfalfa at the rate of 1000 pounds per acre gave a marked increase in crops yield and it resulted in a more efficient use of water by the crops than was obtained without fertilizer, although the total amount of water used was greater with than without fertilizer. The water-use efficiency values for oats usually increased with decreasing available water whereas those for alfalfa were less consistent.The composition in nitrogen, phosphorus, potassium, calcium and magnesium of the plant tissues did not vary greatly. However, the phosphorus content of oats grain decreased with increasing soil moisture stress unless fertilizer was added, indicating that soil phosphorus became less available for oats at high moisture stress.