Comparison of soil zinc extractants for detection of applied zinc and prediction of leaf zinc concentration

• Published in: Communications in soil science and plant analysis Vol. 26; no. 17/18
• Main Authors: Davis, J.G. (University of Georgia, Tifton, GA.), Gaines, T.P, Parker, M.B
• Format: Journal Article
• Language: English
• Published: 01.10.1995
• Subjects: ANALISIS DEL SUELO; ANALYSE DE SOL; ARACHIS HYPOGAEA; CINC; CONTENIDO MINERAL; DISPONIBILIDAD DE NUTRIENTES; DISPONIBILITE D'ELEMENT NUTRITIF; FEUILLE; HOJAS; PH DEL SUELO; PH DU SOL; PROPIEDADES FISICO-QUIMICAS SUELO; PROPRIETE PHYSICOCHIMIQUE DU SOL; TECHNIQUE DE PREVISION; TECNICAS DE PREDICCION; TENEUR EN ELEMENTS MINERAUX; ZINC
• ISSN: 0010-3624; 1532-2416
• DOI: 10.1080/00103629509369501

Many soil extractants have been developed for determination of zinc (Zn) availability to plants. The optimum soil Zn extractant should be useful not only for prediction of plant Zn concentration but also for detection of applied Zn levels. The objectives of this study were: i) to compare soil Zn extractants for detecting applied Zn and for predicting peanut leaf Zn over a range of soil pH levels, and ii) to correlate other soil-extractable Zn levels with Mehlich-1. Soil and peanut leaf samples were taken from a field study testing pH levels as the main plots and Zn application rates in the sub-plots. Extractable Zn was determined on soil samples using Mehlich-1, Mehlich-3, DTPA, MgNO3, and many dilute salt extractants of varied strength and pH. Correlation of extractable soil Zn to cumulative applied Zn levels revealed Mehlich-1, Mehlich-3, DTPA, and AlCl3 extractants to be among the best indicators of applied Zn. Leaf Zn concentration was best correlated with soil Zn extracted by dilute salts, such as KCl CaCl2 NH4Cl, CaSO4, and MgCl2. Including soil pH as an independent variable in the regression to predict leaf Zn considerably improved R-square values. The DTPA-extractable soil Zn levels were very well correlated with Mehlich-1-extractable Zn. Mehlich-3 extracted about 20% more soil Zn than Mehlich-1, but Mehlich-3 soil Zn was not as well correlated to Mehlich-1 soil Zn as DTPA soil Zn. Lower pH solutions extracted more of the applied Zn, but more neutral solutions extracted Zn amounts which were better correlated with Zn uptake. On the other hand, Mehlich-1, which had a lower pH, had better correlations with both applied Zn and leaf Zn than did Mehlich-3. Shortening the DTPA extraction time to 30 minutes resulted in better correlations than the standard two hour extraction time. Chloride (Cl) was the best anion tested in relation to soil applied Zn recovery in combination with potassium (K), calcium (Ca), and aluminum (Al), and Cl optimized leaf Zn correlations