CULTURAL PRACTICES FOR SOYBEANS COMPARED
by Donald e. Null, Regional Agronomy Specialist
January 25, 2000
Summary: The data from this experiment suggests that the most
profitable weed control and soybean variety system in a conventional
seed/weed control program was the one using a farmer-saved, high yielding
soybean line (the least expensive soybean seed) along with a weed control
program that included an incorporated soil applied grass and small seeded
broadleaf weed control herbicide followed by an early post broadleaf weed
control treatment and cultivation.
Objective: To compare the value of various soybean production methods.
Situation: Producers are being faced with difficult financial
conditions. Soybeans are selling at levels below FSA loan levels. Production
costs are being examined to determine if reductions can be made without a
reduction in crop yield. This experiment was set up to help answer the
question "Can I reduce crop inputs without hurting crop yield?"
Experimental Treatments: Nine treatments were selected. The variables included
seed source and method of weed control, including cultivation. The seed used
included private brand Northrup King NK43B5, public variety Maverick and
"farmer saved" seed. The "farmer saved" seed was from a 1998 field of beans
planted to NK43B5.
Weed control, for each seed source, included the following:
- PPI Treflan followed by cultivation as needed (treatments 1-3)
- PPI Treflan followed by Epost Galaxy (treatments 4-6)
- PPI Treflan followed by Epost Galaxy followed by cultivation as needed (treatments 7-9)
Methods: The study was designed as a randomized complete block with six
replications. Plot size was 12' wide and 30' long.
Soybean seed was secured from a local Gentry county dealer. Treflan was
preplant incorporated on May 28 to all plots. Soybeans were planted at the rate
of 180,000 seeds per acre in 36" wide rows on June 3 using a John Deere vacuum
type, max-emerge planter. Weed pressure was heavy in the plot area. The two
most dominant weeds were sunflower and giant foxtail.
A John Deere RM4 row crop cultivator was used for cultivating the plots. Three
cultivations were required for the Treflan only plots. They were made on June
19, July 6 and July 19. Two cultivations were made to one set of the Treflan
followed by Galaxy plots and the other set was not cultivated. The dates for
these cultivations were July 6 and 19.
Herbicide applications consisted of Treflan, applied at 1 quart per acre and
incorporated with a tandem disk (2X) to all plots. Galaxy was applied early
post on June 18 at the rate of 1 quart/acre with 0.25% v/v of crop oil
concentrate and 6.25 pounds of spray grade ammonium sulfate per 100 gallon of
spray solution to treatments 4-9.
Results: The soybean varieties yielded from 34.0 to 36.2 bu/acre in the highest
yielding, most weed free plots. There were statistically no difference in
yields between the public, private and farmer saved varieties in this study
(LSD, P.05 =3.1 bu/acre). While not statistically significant, it is
interesting to note that in every weed control scenario, the private brand
soybean provided the highest yield while the public variety provided the lowest
yield.
Effect of Weed Control Method and Seed Source on Soybean Yield
----------------------------------------------------------------------
Yield in Bushels/acre
----------------------------------------------
Weed Control Method Farmer Saved Maverick Northrup King
43B5 (Public variety) NK43B5
----------------------------------------------------------------------
PPI Treflan + Cultivation 23.9 21.9 26
PPI Treflan + Epost Galaxy 31.8 29 32.2
PPI Treflan + Epost Galaxy
+ Cultivation 35.2 34 36.2
LSD 0.05 5.8
----------------------------------------------------------------------
Cultivation of the Treflan followed by Galaxy treatments provided an increase
of 4 bu/acre over the uncultivated Treflan followed by Galaxy treatments,
however this difference was statistically insignificant (LSD = 4 bu/a).
The lowest yielding treatments were the cultivation only treatments. This was
likely due to the lack of weed control, especially sunflower. Sunflower control
ranged from 40-60% in the PPI Treflan followed by cultivation treatments.
Treatments receiving the early-post Galaxy plus cultivation provided 98% or
better sunflower control. The table below shows that the cultivation of the PPI
Treflan followed by Galaxy treatments did improve total weed control, but the
improvement in weed control was not statistically significantly.
Effect of Weed Control Method on Overall Weed Control
(average of five weed species1)
----------------------------------------------------------------------
Percent Weed Control
---------------------------------------------
Weed Control Method Farmer Saved Maverick Northrup King
43B5 (Public variety) NK43B5
----------------------------------------------------------------------
PPI Treflan + Cultivation 84.3 80.7 83
PPI Treflan + Epost Galaxy 94.8 94.5 96.5
PPI Treflan + Epost Galaxy
+ Cultivation 98.3 98.6 99.2
LSD 0.05 5.1
----------------------------------------------------------------------
(1) Average of giant foxtail, sunflower, cocklebur, waterhemp and
velvetleaf
These data would suggest that the most profitable weed control and soybean
variety system in this 1999 experiment was the one using the least expensive
soybean variety along with the PPI Treflan followed by Epost Galaxy and
cultivation. The economic data, not adjusted for statistical significance is
in the table below.
|
Treatment
|
Overall Weed control1
|
Seed cost/a2
|
herbicide cost3
|
cultivation cost4
|
Total cost/a5
|
Bu/acre yield
|
Value of yield6
|
Return after seed and weed control7
| |
Treflan + cultivation NK43B5
|
83
|
$21.80
|
$12.83
|
$18.96
|
$53.59
|
26.0
|
130.00
|
$76.41
| |
Treflan + cultivation Maverick
|
81
|
$12.38
|
$12.83
|
$18.96
|
$44.17
|
21.9
|
109.50
|
$65.33
| |
Treflan + cultivation farmer saved seed
|
84
|
$9.60
|
$12.83
|
$18.96
|
$41.39
|
23.9
|
119.50
|
$78.11
| |
Treflan f/b Galaxy NK43B5
|
96
|
$21.80
|
$33.91
|
$0.00
|
$55.71
|
32.2
|
161.00
|
$105.29
| |
Treflan f/b Galaxy Maverick |
94
|
$12.38
|
$33.91
|
$0.00
|
$46.29
|
29.0
|
145.00
|
$98.71
| |
Treflan f/b Galaxy farmer saved seed
|
95
|
$9.60
|
$33.91
|
$0.00
|
$43.51
|
31.8
|
159.00
|
$115.49
| |
Treflan f/b Galaxy f/b cultivation NK43B5
|
99
|
$21.80
|
$33.91
|
$12.64
|
$68.35
|
36.2
|
181.00
|
$112.65
| |
Treflan f/b Galaxy f/b cultivation Maverick
|
99
|
$12.38
|
$33.91
|
$12.64
|
$58.93
|
34
|
170.00
|
$110.07
| |
Treflan f/b Galaxy f/b cultivation farmer saved seed
|
98
|
$9.60
|
$33.91
|
$12.64
|
$56.15
|
35.2
|
176.00
|
$119.85
|
(1) Average of 5 weed species (Giant foxtail, cocklebur, common waterhemp, velvetleaf and wild sunflower)
(2) NK43B5 had 2800 seeds/lb and cost $16.95/50 lb. bag. Farmer saved seed had 2500 seeds/lb and cost $8.00/bu. Maverick had 3200 seeds/lb and cost $11.00/50 lb. bag
(3) Treflan cost is $8.33/acre and Galaxy treatment costs are $16.57/acre. An application charge of $4.50/acre is applied to each application.
(4) Cultivation cost of $6.32 from custom rate guide G302 (March 98) average rate.
(5) Total cost is cost of seed and weed control only.
(6) Based on a value of $5.00/bushel selling price.
(7) The amount left to pay for all expenses after seed and weed control.
|
