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 Walgenbach, R. P. Articles by Ream, H. W. Search for Related Content PubMed Articles by Walgenbach, R. P. Articles by Ream, H. W. Agricola Articles by Walgenbach, R. P. Articles by Ream, H. W.

Growth and Chemical Composition of Alfalfa Fertilized in Greenhouse Trials with Deproteinized Alfalfa Juice¹

Alfalfa (Medicago sativa L.) needs adequate fertilization to maintain herbage yields. The deproteinized alfalfa juice (DAJ) remaining after the protein is extracted from green alfalfa has been used to fertilize alfalfa and other crops. However, plant damage occurred when the DAJ was applied at depths greater than 1.25 cm. The purpose of this greenhouse study with alfalfa was to observe more closely the possible causes of plant damage when DAJ is applied as fertilizer. DAJ was applied to alfalfa stubble after herbage harvest, and the alfalfa was cut three times at 24-day intervals. Alfalfa plants were growing in Piano silt loam soil (Typic Argiudoll) in Exp. 1, and in Miami silt loam soil (Typic Hapludalf) in Exp. 2. In Exp. 1, DAJ rates were 0, 1.25, 2.5, 5.0, 7.5, and 10.0 cm, and in Exp. 2, rates were 0, 0.16, 0.31, 0.62, 1.25, and 2.50 cm. Treatments also included two rates of K as K₂SO₄ and the ashed equivalent (AE) of 5.0 cm DAJ in Exp. 1 and of 1.25 cm in Exp. 2. Alfalfa plants fertilized with DAJ at rates of 1.25 cm or higher showed chlorotic symptoms and growth retardation. Only a few plants survived at the 5.0, 7.5, and 10.0 cm rates. Plants fertilized with K₂SO₄ and with AE of DAJ grew normally. First-harvest and overall herbage yields were imilar to those of the control, except for significantly lower yields at 5.0, 7.5, and 10.0 cm rates in Exp. 1. Concentratious of N, K, Cl, and Mn in first-harvest herbage generally were increased by DAJ treatments, while other elements were decreased or were similar to control herbage. Soil salt indexes (conductivity of soil solution) increased with each increase in DAJ, but initial plant damage at high DAJ levels did not appear to be due to salt accumulation nor to any elemental toxicity. It is concluded that unknown-phytotoxius contained in the DAJ or produced as microfloral breakdown products are the probable causes of plant damage. Further work is needed to identify these phytotoxic substances.

Key Words: Medicago sativa • Herbage yields • Herbage elemental composition • Phytotoxicity • Soil salt index

² Graduate research assistant, professor, and visiting professor, respectively, Dep. of Agronomy, Univ. of Wisconsin, Madison, WI 53706.

Received for publication October 6, 1976.