Comparison and evaluation of soil test methods for manganese and iron

Author

Ronald Rollins Sharpe

Date of Award

12-1979

Degree Type

Thesis

Degree Name

Master of Science

Major

Plant, Soil and Environmental Sciences

Major Professor

W. L. Parks

Committee Members

R. J. Lewis, G. M. Lessman

Abstract

Seventy-one soil samples, representing seven soil series, and seventy plant samples were collected from three physiographic regions in Tennessee. The plant samples consisted of 4 corn, 8 tobacco, 18 cotton, and 40 soybean samples. Soil manganese was extracted by NH₄OAc, DTPA and Double Acid procedures. Soil iron was extracted by the DTPA and Double Acid procedures. Soil pH and the soil concentrations of calcium, phosphorus and potassium were also determined for each sample. Concentrations of manganese and iron were determined for each plant sample.

The chemical extractant, soil series, and their interactions significantly affected the amount of manganese measured, but only chemical extractants and interactions significantly affected the amount of iron extracted. The Double Acid procedure extracted the most manganese with the DTPA procedure intermediate and the NH₄OAc procedure extracting the least. The Double Acid procedure extracted slightly more iron than the DTPA procedure.

The correlations among manganese extractants were high. There was a negative correlation between the three manganese extractants and pH, but the correlation was less between manganese extracted by the Double Acid and pH than between DTPA and NH₄OAc extractants and pH. There was a poor correlation between the iron extractants. DTPA-extractable iron correlated well with pH, but iron extracted by the Double Acid procedure did not.

Correlations between soil manganese and manganese in soybean plants were high for all three manganese extractants. Correlations between manganese extracted by the NH₄OAc and DTPA procedures and manganese in cotton plants were very high, but the correlation between Double Acid extractable manganese and manganese in cotton plants was not significant, None of the correlations between the iron extractants and iron in plants were significant.

Multiple regression equations, using soil manganese, iron, calcium, and pH were used to predict plant manganese concentrations. Using the 2 squared terms of the elements in the equation increased the R² values in all cases. Manganese extracted by NH₄OAc gave the highest R² value for predicting manganese in cotton plants, and manganese extracted by the Double Acid procedure gave the highest R² value for predicting manganese in soybeans. DTPA-extractable manganese gave acceptable results for both cotton and soybean plants.

Recommended Citation

Sharpe, Ronald Rollins, "Comparison and evaluation of soil test methods for manganese and iron. " Master's Thesis, University of Tennessee, 1979.
https://trace.tennessee.edu/utk_gradthes/7803