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

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (8) Citing Articles via Google Scholar Google Scholar Articles by Parker, D. R. Articles by Sparks, D. L. Search for Related Content PubMed Articles by Parker, D. R. Articles by Sparks, D. L. Agricola Articles by Parker, D. R. Articles by Sparks, D. L.

Potassium in Atlantic Coastal Plain Soils: II. Crop Responses and Changes in Soil Potassium Under Intensive Management

Dep. of Soil and Environmental Sciences, Univ. of California, Riverside, CA 92521

G. J. Hendricks and D. L. Sparks

Dep. of Plant Science, Univ. of Delaware, Newark, DE 19717-1303

* Corresponding author.

ABSTRACT

Corn (Zea mays L.) grown on sandy Atlantic Coastal Plain soils is often unresponsive to applications of K fertilizer. The purpose of this investigation was to examine the response of irrigated, intensively managed corn to K applications, and to monitor changes in soil K status. Field studies were conducted for 3 yr at four sites on the Delaware Coastal Plain. Treatments consisted of 0, 94, or 282 kg ha^–1 applied K, both as a single application and in three split applications. Grain yields were high (6.9 to 14.0 Mg ha^–1), but were not significantly (p 0.05) affected by K application for any year-site combination. Similarly, corn ear leaves at silking contained adequate K (20 to 30 mg kg^–1), although these concentrations varied with K application rate on the two sandier soils. In the zero K plots, dilute double acid-extractable K concentrations ranged from 56 to 194 mg kg^–1 at the start of the study, and had declined by 29 to 45% by the end of the third growing season. Evidence was obtained for both leaching of applied K and conversion to nonexchangeable forms. The lack of observed yield response was ascribed to (i) modest crop removal of K when corn is harvested only for grain, (ii) adequate K-buffering capacity of these soils to meet high crop demands during the growing season, and/or (iii) availability of significant quantities of subsoil K. Our results further suggested that, despite the high grain yields obtained, current recommendations by several state soil testing laboratories in the region are, if anything, somewhat excessive in that K fertilizer is recommended even when no yield response is observed.

Published with the approval of the director of the Delaware Agric. Exp. Stn. as Miscellaneous Paper no. 1250. Contribution no. 242 of the Dep. of Plant Science, Univ. of Delaware.

Received for publication June 20, 1988.