Relation between the amounts of Ca,Mg, and k extracted from organic soils and their concentration in onion and alfalfa tissue

Abstract

The objective of this work was to appraise the double acid (0.05N HCl+0.025N H₂SO₄) extraction agent for assessing the availability of Ca, Mg, and K in organic soils. The evaluation was done by determining the relation and interactions between the concentrations of Ca, Mg and K extracted from soils and those found in onion and alfalfa tissues.

The extraction procedure was found to give good relations (r ≥ 0.848^**) between the concentrations of Ca and Mg extracted from soils and those present in onion and alfalfa tissues, though interactions between the amounts of Ca and Mg extracted from soils were found.

A differentiation among soils was found upon relating the amounts of soil extracted K to its concentration in onion and alfalfa tissues. Soil extracted K was shown to be related to its preponderance (K x 100/K Ca Mg) over other extracted bases (r = 0.975^**). A critical preponderance of 11% K was identified for alfalfa. The critical preponderance of K in crops appraises some of the interactions among available soil cations and, consequently, is suggested as an improved approach for predicting crop response to potassium fertilization.