Group Title: Research report (North Florida Research and Education Center (Quincy, Fla.))
Title: Response of soybean to residual p and k after canola and triticale
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00066113/00001
 Material Information
Title: Response of soybean to residual p and k after canola and triticale
Series Title: Research report (North Florida Research and Education Center (Quincy, Fla.))
Physical Description: 6 leaves : ill. ; 28 cm.
Language: English
Creator: Rhoads, Fred ( Frederick Milton )
Barnett, Ronald David, 1943-
North Florida Research and Education Center (Quincy, Fla.)
Publisher: North Florida Research and Education Center
Place of Publication: Quincy Fla
Publication Date: 1993
 Subjects
Subject: Soybean -- Florida   ( lcsh )
Soils -- Testing   ( lcsh )
Genre: non-fiction   ( marcgt )
 Notes
Statement of Responsibility: F.M. Rhoads and R.D. Barnett.
General Note: Cover title.
 Record Information
Bibliographic ID: UF00066113
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 71173874

Full Text

~d3(o~vt


lMarston Science
Library
SEP 2 3 1993


NFREC Res. Rpt. 93-11


University of Florida


RESPONSE OF SOYBEAN TO RESIDUAL P AND K

AFTER CANOLA AND TRITICALE





F. M. Rhoads and R. D. Barnett





NORTH FLORIDA RESEARCH AND EDUCA TION
CENTER, QUINCY



Florida Agricultural Experiment Stations
Institute of Food and Agricultural Sciences
University of Florida, Gainesville

h UNIVERSITY OF
3 FLORIDA









RESPONSE OF SOYBEAN TO RESIDUAL P AND K
AFTER CANOLA AND TRITICALE

Canola (Brassica napus), a new crop for North Florida, is an
oilseed crop that has been genetically altered to give an improved
version of rapeseed. It has broad leaves and is a member of the
cruciferae (mustard) family. Canola oil is used for cooking
because of its low saturated fat content (6%). Triticale is a
hybrid small grain as a result of crossing wheat (Triticum aestivum
L. em. Thell) with rye (Secale cereale L.) These two crops, canola
and triticale, can be grown in rotation to reduce weed population
and plant disease and increase farm income. However, in the
southeastern US, growing only cool season crops results in the land
being out of production during the warm season. Since canola and
triticale are harvested in late May or early June, soybean (Glycine
max L.) is an ideal summer crop to follow them because the
recommended planting dates for it fall between May 15 and June 15.

Our objective was to evaluate the response of soybean to
residual soil-test phosphorus (P) and potassium (K) following
canola and triticale. Also, we were interested in determining if
soybean responded different after canola as compared to after
triticale and if there were any interactions between cool season
crops and fertilizer treatments that influenced soybean response.
However, there was some influence from canola in triticale plots
because of previous cropping history (one crop of canola was grown
a year before triticale). Likewise, triticale was grown before
canola in the current canola plots.

METHODS

Soybean (Coker 488) was planted June 17, 1992 in NFREC
fertility plots where canola and triticale were grown in the winter
of 1991-92. Row width was 30" and plot dimensions were 20'X15'.
Soil type was Norfolk loamy fine sand (fine-loamy, siliceous,
thermic, Typic Kandiudult). Irrigation was applied as needed to
reduce plant-water stress.

No fertilizer was applied to the soybean crop because of the
objective to evaluate response to residual P and K applied to
canola and triticale. Rates of P2Os applied to canola and
triticale were 0, 75, and 150 lb/acre and rates of K0O were 0, 150,
and 300 lb/acre. Soil samples were collected from the 0-6 inch
depth of each plot on July 9, 1992. Ten 1X6 inch cores were mixed
together from each plot to form a composite sample. Mehlich-1
(double acid) extractant was used to remove P and K from the air
dried soil samples. Soil analyses were carried out according to
the University of Florida Extension soil-testing laboratory
procedures (Hanlon and Devore, 1989).

Soybean plant samples were collected from each plot on October
2, 1992. Whole plants (above ground portion) from a three foot
section of row in the center of each plot were cut at ground level









and dried at 700 C. Dry plant samples were ground to pass a 20-mesh
screen, washed at 5000 C, and dissolved in dilute HC1 for P and K
determination. Phosphorus was determined by the molybdenum blue
method and K was determined with a flame emission
spectrophotometer. Nutrient uptake was calculated from
concentration and dry weight of samples from 3 ft of row.

The experimental design was a split-plot randomized complete
block with four replications. Whole plots were previous crop
(canola or triticale) and sub-plots were fertilizer treatments.
Analysis of variance was used to calculate least significant
differences (Isdo.0) between fertilizer treatments (Freed, 1988).

RESULTS

There was no significant difference due to previous crop on
soybean response to P and K. However, the fact that canola was
grown the year previous to triticale and vice versa may mask out
any difference in soybean response to the previous crop.

Soil-test P was in the low range (10-15 ppm) in plots (Table
1.) that received no P fertilizer (Hanlon et al., 1990). Plots
that received 75 lb of P205 per acre had an average soil-test P of
22 ppm which is in the medium range (16-30 ppm) and those that
received 150 lb/acre of P2Os had an average soil-test P of 33 ppm
which is in the high range (31-60 ppm). Soil-test P of 40 ppm
occurred in plots that received 240 lb/acre of P2Os for a period of
* six years but only 150 Ib/acre was applied to canola and triticale
in 1991-92. Both % P and yield of soybean responded positively to
soil-test P (Table 1.). Yield response was quadratic and maximum
yield occurred in the high soil-test range (Fig. 1.). Predicted
maximum yield was near the soil-test P level of 52 ppm which agrees
with the philosophy that no fertilizer should be applied that
contains elements in the high soil-test range.

Soil-test K ranged from 52 to 104 ppm (Table 2.), this shows
that plots receiving no K had soil-test K in the medium range (36-
60 ppm) while those that received 150 and 300 lb/acre of K0O were
both in the high range (61-125 ppm). Both % K and yield of
soybean responded positively to soil-test K (Table 2.). Yield
response to K was linear with 0.138 bu/acre per ppm of soil-test K,
however, 300 lb/acre of K20 did not result in a significant increase
in soil-test K in comparison with 150 lb/acre. Since canola and
triticale yields were not increased between 150 and 300 lb/acre of
K0O, it appears that 150 Ib/acre per year is adequate for this
cropping system unless it is applied directly to soybean.

A yield response of soybean to P was not expected when
residual soil-test P after canola or triticale was above 52 ppm,
this agrees with Florida Extension Service soil-test
recommendations. Yield response of soybean to K between medium and
high soil-test K was 0.138 bu/acre per ppm K. Assuming that 150
lb/acre of KO would increase soil-test K by 50 ppm, then 0.138 bu









of soybeans should have a higher value than 3 lb of K20 for
additional K to be profitable. Thus, a soybean price of $5 per
bushel and a cost of $200 per ton of sulfate of potash should
produce 15% profit in the soil-test K ranges of medium and high.

REFERENCES

1 Freed, R. D. 1988. MSTAT-C: A microcomputer program the
design, management,and analysis of agronomic research
experiments. Michigan State University.

2 Hanlon, E. A. and J. M. Devore. 1989. IFAS extension soil
testing laboratory chemical procedures and training manual.
Fla. Coop. Ext. Serv. IFAS. Univ. of Fla. Cir. 812.

3 Hanlon, E. A., G. Kidder, and B. L. McNeal. 1990. Soil,
container media, and water testing interpretations. Fla.
Coop. Ext. Serv. IFAS. Univ. of Fla. Cir. 817.




ACKNOWLEDGEMENT

This research received financial support from the Florida
Agricultural Experiment Stations and the Potash and Phosphate
Institute.









Table 1. Soil-test phosphorus (P), % P in plants, P uptake, and
yield of soybean following canola and triticale, summer of 1992.
Soil-test P P uptake Yield
mq kg-1 % P lb/acre bu/acre


Isdo.o


0.13

0.15

0.16

0.19

0.03


6.5


6.2

8.0

10.0

9.7

2.1


39

45

49

49

5.6


Table 2. Soil-test potassium (K), % K in plants, K uptake, and
yield of soybean following canola and triticale, summer 1992.
Soil-test K K uptake Yield
mg kg' % K Ib/acre bu/acre


52

91

104


1.24

1.95

2.10


101

130


lsd0*~ 18 0.13 26 5.6


Q


isdo. 18


0.13 26


5.6

















Fig.-1. Seed yield of soybean vs
soil-test P.

Soybean Yield, bu/acre
50
R 0.647




30

Y 29.12 0.859X 0.00819X(2)
!0 .....-- Source

10 .- Regression
x Treat. Means
0
0 10 20 30 40 50 60
Soil-Test P, ppm

Fig.-2. Seed yield of soybean vs
soil-test K.

Soybean Yield, bu/acre


60

5 0 ...........

40-

30 r 0.702

20 Y--34.51 + 0.138X-
2 0 ................; 8 ... .............................................
10-


0 20 40 60 80 100 12
Soil-Test K, ppm


Source
- Regression

x Treat. Means


0




University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs