PLANT ANALYSIS AS A DIAGNOSTIC PROCEDURE

Abstract

The conc. of a nutrient in the plant as a whole or in any part of it is a function of soil, climate, plant, time, management, and possibly other factors. At any one time a chemical analysis of the plant or part of the plant gives an integrated value of all the factors that have influenced its nutrient composition. By comparing the nutrient changes taking place during the development of the crop with previously established critical levels the nutrient status of the plant may be ascertained. Plants with nutrient concs. above the critical values may be considered adequately supplied at that moment; plants with values within the critical range may be considered inadequately supplied. The longer a deficiency persists, and the earlier during the growth cycle it occurs, the greater is the likelihood of a response upon the application of the deficient nutrient. The many factors affecting the conc. of a nutrient in the plant may account for the frequent failure of soil analysis to serve as a satisfactory guide for fertilizer practices. The limited variations found in the critical K concs. of appropriate plant tissues give hope that useful interpretations of soil needs may be made on the basis of plant analysis. The sensitivity of plant tests depends upon the part of the plant analyzed, the particular fraction of the nutrient determined and the position on the plant from which the sample is selected.