Aluminum Accumulation in Vegetable Amaranth Grown in a Soil with Adjusted pH Values

Abstract

Abstract Two levels of phosphorus (20 and 80 kg P/ha) and two levels of aluminum (0 and 85 kg Al/ha) were applied to Enders soils of pH 4.4, 6.6, or 7.3. Sixteen-day-old vegetable amaranth (Amaranthus tricolor L.) plants (Rodale Research Center Accession 241) were transplanted 24 July 1986 and harvested 27 days later. Increasing soil pH from 4.4 to 7.3 decreased plant height, fresh weight, leaf area, leaf blade chlorophyll, N, K, Mn, and Zn, but increased Ca, Mg, Al, and Na (dry-weight basis). Supplemental P increased plant height, leaf area, plant dry weight, leaf blade P, K, Ca, Mg, Na, and chlorophyll; decreased Fe, B, Zn, and Al; but had no effect on leaf blade protein. Adding Al to the soil decreased plant height, leaf blade chlorophyll, N, P, and Na, but increased Mn. At the termination of the experiment, exchangeable soil Al was found only in soil at pH 4.4 (1.1 cmol·kg-1). The highest leaf blade Al concentration (2473 mg·kg-1) was found in soil at pH 6.6 that received the low rate of supplemental P. Regardless of soil pH, leaf blade Al was negatively correlated with plant height (r = -0.78), plant dry weight (r = -0.78), available soil P (r = -0.51), and leaf blade P (r = -0.53), but it was positively correlated with Fe (r = 0.98).