Indexes of Sulfur Deficiency in Alfalfa. II. Plant Analyses

Westermann, D.T. (1975) Indexes of Sulfur Deficiency in Alfalfa. II. Plant Analyses. Agronomy Journal. 67(2):265-268.

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Abstract

Both soil and plant analysis are diagnostic tools used
in identifying S deficiencies; however, soil tests evaluating
soil S availability levels are not always successful and
deficiencies must then be identified by plant analysis.
In addition, the diagnostic tool must be correlated to crop
responses under various growing conditions to be useful.
Identification of S deficiency on alfalfa (Medicago sativa
L) in southern Idaho permitted the collection of correlation
data for both S soil tests and plant analyses. The
S soil test correlation data has been previously reported
(Aron. J. 66:578-581, 1974). This paper reports the relationships
found between the plant S indexes of total S,
SO₄-S and total (N/S) ratio, and the response of alfalfa to
S fertilization. All data were evaluated by correlation
analyses.

The total S and SO₄-S concentrations and the total
(N/S) ratio were all found to be satisfactory indexes of
S deficiency in whole alfalfa at early bloom. Maximum
forage yields were obtained when the tops contained
between 0.15 to 0.20% S or 0.05% SO₄-S. Total S and
SO₄-S were related and readily interchangeable as indexes.
Increases in total S above 0.14% S resulted from
the accumulation of SO₄-S. Yield responses to S fertilization
were obtained when the total (N/S) ratio was greater
than 17 to 18. Total N and total S were not related, but
protein N increased linearly as protein S increased. The
protein (N/S) ratios were not constant and increased
from 17 to 23 as the degree of S deficiency increased.

Item Type:	Article
NWISRL Publication Number:	0312
Subjects:	Irrigated crops > Alfalfa Research methodology Mass Import - autoclassified (may be erroneous)
Depositing User:	Dan Stieneke
Date Deposited:	20 Nov 2010 21:51
Last Modified:	15 Feb 2017 22:43
Item ID:	274
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/274