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 Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Welch, L. F. Articles by Pendleton, J. W. Search for Related Content PubMed Articles by Welch, L. F. Articles by Pendleton, J. W. Agricola Articles by Welch, L. F. Articles by Pendleton, J. W.

Soybean Yields with Direct and Residual Nitrogen Fertilization¹

The objective of this research was to determine the effect on soybean (Glycine max (L.) Merrill) yields of N added at different rates by different times and methods of application, as direct and residual, and as inorganic and organic sources. A number of studies were conducted over a period of several years at 10 field locations in Illinois.

Nitrogen at rates up to 360 kg/ha added for corn (Zea mays L.) the preceding year had no effect on soybean yields. Neither were soybean yields increased by organic sources of N such as manure or alfalfa (Medicago sativa L.), or by combinations of organic and inorganic sources.

Fertilizer N added for soybean as plow-down, disked-in, and side-dressed at early flowering and at pod filling did not increase yields. Nitrogen added for soybeans planted on four dates did not increase yields. High rates of N (1800 and 1440 kg/ha), broadcast and disked-in in the spring, decreased yield due to germination and seedling injury. Considering all the studies, yields were significantly increased in only 3 out of 133 instances and these occurred at high, uneconomical rates of N fertilizer.

It is concluded that N available to the plant is not the growth factor that presently limits soybean yields in Illinois.

Key Words: Fertilizer injury • N fixation • organic N • N application methods

² Professor of Soil Fertility, Agronomist, Agronomist, Assistant Professor of Soil Fertility, Agronomist, Agronomist, and Professor of Agronomy (now Chairman, Department of Agronomy, University of Wisconsin), respectively, University of Illinois, Urbana.

Received for publication October 13, 1972.