Response of Corn in the Greenhouse to Soil Applied Zinc and a Comparison of Three Chemical Extractions for Determining Available Zinc

Abstract

AbstractThe response of corn (Zea mays L.) to applied Zn on 12 Maryland soils was investigated in the greenhouse. Zinc was thoroughly mixed with soils at the rate of 0, 1.25, 2.5, 5, 10, 20, and 40 ppm Zn as zinc sulfate. Corn was grown for 30 days after emergence and dry matter yields were determined. The plant tissue was analyzed for Zn, Ca, Mg, K, and P.The application of Zn increased the dry matter yield of corn on only one of the 12 soils. As the Zn rate was increased, the Zn content of the corn usually increased. The level of Zn in the corn tissue above which no further significant increase in yield was obtained was about 12 ppm.Three chemical soil extractants were compared for determining available soil Zn. The Zn extracted by each of the three chemical extractants was correlated with the Zn content of the above ground portions of the corn plants. The correlation coefficient for the 0.05N HCl plus 0.025N H2SO4 extractant was 0.834, the 0.1N HCl extractant 0.854, and the 0.01M EDTA plus 1.0M (NH4)2CO3 extractant 0.787, respectively. The r values for all three extractants were statistically significant at the 1% level.The level of extractable Zn in an Othello soil which gave a significant dry weight increase in corn following the application of Zn was 0.3 ppm for the HCl plus H2SO4 extractant, 0.2 ppm for the HCl extractant, and 0.1 ppm for the EDTA plus (NH4)2CO3 extractant, respectively.