The Effect of Limestone and Fertilizer Treatments upon the Growth and Composition of Spinach

THE influence of certain nutritional elements upon the growth and composition of spinach has been investigated by various workers. True, Black, and Kelly (i8) studied the effects of the major plant nutrients upon the composition of spinach ash. Bizzel (3) noted that ammonium sulfate caused the mobilization of calcium and potassium into the spinach plant while sodium nitrate did not produce this action. Cook and Millar (6) showed that the addition of borax to Thomas sandy loam resulted in an increased boron content of the dry tissue of spinach tops and roots, a decrease in the nitrogen and iron content, and no significant change in the calcium and magnesium content. A number of workers (15, 16, 22) have demonstrated that the desirable pH for maximum spinach production lies somewhere between 6.O and 7.0. In a series of studies Schroeder and Albrecht (i, 13, 14) attempted to distinguish between pH per se and the effect of calcium upon spinach production. They have shown that the fresh and dry weights of spinach at two hydrogen ion levels (pH 6.8 and 5.2) increased with increasing calcium additions. These weights were greater in the pH 6.8 series than in the pH 5.2 series, but there was a greater mobilization of nutrients into the spinach plant when the soil was acid than when it was neutral. Leaf analyses as a diagnostic procedure for determining the level of soil fertility have been used successfully by a number of workers (4, 8, 17, 20). The following study was carried out to show the effect of pulverized limestone and various fertilizer ratio treatments upon the composition and yield of spinach grown on three typical western Washington soil types and to interpret the results obtained by the use of leaf analysis. •