HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Mallarino, A. P. Articles by Higashi, S.L. PubMed Articles by Mallarino, A. P. Articles by Higashi, S.L. Agricola Articles by Mallarino, A. P. Articles by Higashi, S.L. Related Collections Nutrient Management

NUTRIENT MANAGEMENT & SOIL & PLANT ANALYSIS

Assessment of Potassium Supply for Corn by Analysis of Plant Parts

^a Department of Agronomy, Iowa State University, Ames, IA 50011
^b Formerly a graduate student assistant at, Iowa State University
^c Currently at, USDA Forest Service, 333 SW First Avenue, P.O. Box 3623, Portland, OR 97208

^* Corresponding author (apmallar{at}iastate.edu).

Tissue testing of corn (Zea mays L.) ear leaves often is used to diagnose K deficiencies. However, little attention has been given to study how testing of different corn tissues evaluates K supply especially in the optimum to excess range. We evaluated tissue tests for corn based on the K concentration of young plants (V5 to V6), ear leaves at silking, lower stalks at maturity (sections cut from 15 to 35 cm aboveground), and grain. Twenty-eight field trials were conducted in Iowa during 2 yr with fertilizer rates of 0, 56, 112, and 168 kg K ha^–1. Initial soil-test K (STK) by the ammonium acetate extractant (15-cm sampling depth, air-dried samples) was 80 to 266 mg K kg^–1 across sites. Fertilizer K increased grain yield at one site testing 84 mg K kg^–1; and increased the K concentration of plants, leaves, stalks, and grain at 11, 13, 21, and 5 sites, respectively. Published critical K concentrations for corn plants and leaves would have incorrectly indicated deficient soil K supply for yield in many sites. There were upper limits in plants, leaves, and grain K concentrations response to K supply that varied among sites. The limits occurred at STK values of 123, 140, and 148 mg kg^–1, respectively, which are near STK values optimum for grain yield. The lack of an upper limit in corn stalks shows promise for using this tissue to assess K availability from deficiency to luxury uptake or excess. However, the large site-dependent variability in the stalk K concentrations should be recognized as a limitation.

Abbreviations: STK, soil-test K