EVALUATION OF A BLADE CULTIVATOR FOR CONSERVATION TILLAGE
COTTON FOLLOWING CRIMSON CLOVER
Philip J. Bauer1, J o h n G. Alphin2, James R. Frederick3,
and Gloria S. McCutcheon 4
ABSTRACT Coastal Plain soils (Bauer e t al., 1993; Touchton et
al., 1984). The ability o f some crimson clover
Shallow subsurface tillage can control weeds cultivars t o mature and reseed prior t o a mid- t o
and maintain surface residues in conservation late-May cotton planting increases the potential for
tillage systems. Our objective was t o determine utilizing this legume in conservation tillage
the efficacy of using subsurface tillage for weed production systems.
control in cotton (Gossypium hirsutum L.) g r o w n in
a reseeding crimson clover (Trifolium incarnatum L.) Weed control in strip- or no-till systems is
winter cover production system. Treatments in the accomplished primarily with herbicides. In the pre-
study were planting date (15 April, 29 April, and herbicide era, mechanical devices were developed
24 May), winter cover (fallow or 'Dixie' crimson t o control weeds in r o w middles o f crops growing
clover), and midrow weed control method (V-blade in mulch-type cultural practice (Chase, 1942). This
cultivator and glyphosate application). Soil type technology is again being evaluated for modern
was Norfolk loamy sand (fine, loamy, siliceous, crop production. Cultivators are currently available
thermic, Typic Kandiudult). Weed control methods t o growers that will control weeds between rows
were compared in the first t w o planting dates in when large amounts of surface residues are
late May. At one week after treatment, weed present.
control in the mid-rows was similar between
glyphosate application and subsurface tillage in In order for these cultivators t o be most
both planting dates and b o t h winter cover effective in a reseeding crimson clover conservation
treatments. Subsurface tillage reduced residue tillage system, crimson clover seeds must be left
cover in the midrows b y 8%. Weed control near the soil surface after cultivation. The optimal
treatments were applied t o all planting dates in late seeding depth for small seeded legumes like
June. Clover successfully reseeded following both crimson clover is 0.5- t o 1.5-cm (Decker et al.,
weed control methods. These preliminary data 1973). Therefore, secondary cultivation devices
suggest that further investigation o f subsurface which cause significant soil mixing may bury clover
tillage in reseeding crimson clover cotton seeds and result in reduced clover stands the
production systems is warranted. following fall.
INTRODUCTION We used a set of V-blade sweeps t o determine
the efficacy of using this weed control method for
Winter cover crops can be used for soil cotton g r o w n following crimson clover o n a sandy
improvement and erosion control in cotton fields. Coastal Plain soil. In this report, w e present the
O f the legume cover crops, crimson clover may be 1993 results f r o m our comparison of these sweeps
especially suitable in the southeastern USA with a directed application of glyphosate in strip-
because o f its ability t o provide adequate fall tillage cotton g r o w n after a crimson clover cover
g r o w t h and abundant residues (Hoyt and Hargrove, crop.
1984). Crimson clover can also provide all the N
needed b y a succeeding cotton crop on sandy MATERIALS AND METHODS
' USDA-ARS, Coastal Plains Soil, Water & Plant Res. Cen.,
Five independantly acting V-blade cultivator
Florence, SC 29502.
Dept. of Agricultural and Biological Engineering, Clernson units were assembled. Each V-blade and a smooth
Univ., Florence. SC. coulter were attached t o a lower parallel linkage
Dept. of Agronomy and Soils, Clemson Univ.. Florence. SC. frame of a Case-IH Model 183 cultivator utilizing a
'Dept. of Entomology. Clernson Univ.. Florence, SC. gauge wheel for depth control. The standard
gauge wheel attachment was reversed t o give the
desired placement between coulter and V-blade.
V-blade construction consisted of removing nutrients were applied based o n soil test results.
the stem f r o m a 30 inch sweep and replacing the Insecticides were used a t planting to control thrips
stem b y welding a short flat bar attachment, and in late June, late July, and early August f o r
beveled o n t h e front, t o the front portion of t h e Heliothis virescens and Helicoverpa zea control.
sweep. The ends of the sweep were c u t off t o Pre- and post-emergent herbicides were applied
give a 26-in cutting width. The wings have a with a directed sprayer f o r in-row weed control. A
slightly beveled cutting edge. Nominal dimensions traveling gun irrigation system w a s used t o apply
for the blade-wings are 0.25-in thick and 2-in wide. 0.5 in of water t o the plots o n 29 and 30 April and
again o n 3 and 4 June.
The framework was constructed t o provide a
relatively simple means f o r accomplishing the Aboveground biomass of the winter covers
following functions: 1. attaching t o the Case-IH (winter weeds in the fallow plots or t h e crimson
frame; 2. attaching t h e V-blade over a range o f clover) w a s determined b y collecting and drying
fixed distances f r o m the Case-IH support frame (70" C) a sample f r o m each subplot o n
with an adjustable pitch angle; 3. adjusting coulter M a y 17. O n 20 May, m i d r o w weed control
depth; 4. aligning V-blade and coulter with each treatments were applied o n the subplots in the first
other and travel direction; 5. replacing parts for t w o planting dates. On 27 May, t h e amount of
repairs and future investigations. residue cover and live weeds in t h e treated areas
were measured by using a' t w o dimensional
We evaluated this V-blade cultivator o n a transect. A 39-in long and 24-in wide frame w a s
Norfolk loamy sand soil a t Clemson University's constructed f r o m 1 inch PVC pipe. Four parallel
Pee Dee Research and Education Center in strings were streched across t h e frame and
Florence, SC. In this investigation, the V-blade and attached t o the 24-in sides. Six parallel strings
coulter nominal operating depths were 2 and 3-in, were across the 39-in side. O n each side, strings
respectively, with the V-blade set parallel with the were spaced 6 inches apart. Residues and weeds
soil surface. [mainly crabgrass (Digitaria spp.)] were determined
at t h e 24 intersections of t h e strings. Six
The treatments in the experiment were winter determinations were made in each plot. The weed
cover (crimson clover and fallow), planting date (15 control treatments were applied t o all three planting
April, 29 April, and 25 May). and midrow weed dates o n 21 June. The cotton and weeds were
control method [V-blade cultivator and a directed severely water stressed a t that time, so residue and
application of glyphosate (Brewer, 1993) t o the weed determinations were n o t made.
midrowsl. Experimental design was randomized
complete block in split plot arrangement with the Clover cover in early December was measured
winter cover and planting date combinations as in t w o replicates of t h e study b y using a line
main plots and midrow weed control method as transect of 45 ft with 39 evaluation points. Data
subplots. The experiment had four replicates. w a s collected f r o m midrows that had and did n o t
have tractor wheel traffic during the growing
In the fall of 1992, t h e experimental area was season.
disked and harrowed. The cultivar 'Dixie' was
seeded into the crimson clover plots at a rate of 20 All data collected were subjected t o analysis
lb seed ac-1 with a grain drill o n 14 October, 1992. of variance. Mean separations were made b y
calculating a least significant difference.
A t t w o weeks before the April planting dates,
glyphosate was applied in 12-in strips t o kill RESULTS AND DISCUSSION
vegetation where the cotton r o w s were t o be. A
broadcast application of glyphosate was made at The biomass of the crimson clover and winter
one week before the M a y planting date. All plots weeds o n 17 M a y are given in Table 1. Values for
were in-row subsoiled before planting t o a depth of clover in the first two planting dates were low,
18 in. Cotton ('DES 119') w a s planted with a four compared to t h e M a y planting date, because the
r o w no-till planter in 38-in rows. clover in t h e crop r o w s w a s killed with glyphosate
t w o weeks before each planting date in April.
Total N applied t o the cotton in the winter Also, wheel traffic f r o m cotton planting and
fallow plots was 70 lb N o N was applied in applying herbicides (in-row) in t h e April planting
t h e crimson clover plots. Lime and other plant dates reduced clover production in the traffic
Table 1. Clover and winter weed biomass levels Table 2. Reseeded crimson clover cover in non-
measured o n M a y 17, 1993. wheel and wheel mid-rows in late November,
cotton Winter Cover cotton Weed Control Mid-Row
Planting Date Clover Fallow Planting Date Method Non-Wheel Wheel
April 15 860 451 April 1 5 V-Blade 36 54
April 29 1009 243 Glyphosate 57 48
M a y 24 230 1 343
24 1 April 29 V-Blade 59 62
Glyphosate 60 63
M a y 24 V-Blade 90 91
midrows. Winter weed biomass was similar in the Glyphosate 95 95
three planting dates (Table 1).
A severe drought occurred during t h e cotton
growing season in 1993 and limited the value of
our evaluation of t h e V-blade f o r weed control.
The amount of weed control (measured o n 27 M a y ) glyphosate was used t o control weeds in the
at one week after treatment with the V-blade cotton r o w middles (Table 2). In the 15 April
cultivator w a s the same as for the glyphosate planting date, t h e amount of reseeded clover in the
application (data n o t shown). Both had very l o w V-blade cultivator non-wheel mid-rows was less
live weed (mainly Diqitaria spp.) populations. Like than t h e herbicide plots (Table 2). When the clover
t h e w e e d control methods, neither winter cover w a s allowed to fully reseed before planting cotton
treatment n o r planting date influenced the amount (24 M a y planting date), soil cover b y live clover
o f live weeds. plants was greater than 90% for both the V-blade
and glyphosate weed control methods (Table 2).
The amount of residue cover on 27 M a y was
influenced b y planting date, winter cover, and In summary, surface residues were retained and
midrow weed control method, but interactions crimson clover successfully reseeded following the
between these production practices did n o t occur. use of the V-blade cultivator for weed control in
Residue cover was about 1 5 % lower for the 29 1993. These data suggest that further
April planting than the 15 April planting. Crimson investigations of the V-blade cultivator in reseeding
clover provided 16% more residue cover than did crimson clover cotton production systems are
winter weeds (74% f o r clover vs. 5 8 % f o r fallow). warranted.
The V-blade cultivator exposed a small amount ACKNOWLEDGEMENTS AND DISCLAIMER
o f soil. Residue cover in the mid-rows o n 27 M a y
w a s 62% in the V-blade plots and 70% in the This work is a contribution of t h e Coastal Plains
glyphosate plots. M o s t o f the soil exposed was in Soil, Water, and Plant Research Unit of the USDA
a line d o w n the middle of the mid-row where the ARS and the South Carolina Agricultural Experiment
shank holding the V-blades entered the soil. Little Station, Clemson University, Clemson, SC.
or n o soil w a s exposed near t h e end of the blades. Mention o f trademark, proprietary product, or
vendor does n o t constitute a guarantee or warranty
The lack o f soil surface disturbance with the V - of the product by t h e USDA or Clemson University
blade cultivator apparently kept enough of the and does n o t imply its approval t o t h e exclusion of
clover seed in a zone where it could readily emerge other products or vendors that may also be
and become established. In general, soil cover in suitable. The authors thank Bobby Fisher and
the fall b y live clover plants following use o f the V - Willie Davis for technical support.
blade cultivator was only slightly less than when
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1993. Cotton yield and fiber quality response to Forages/The science of grassland agriculture. The
green manures and nitrogen. Agron. J . 85:1019- I o w a State University Press, Ames, Iowa.
Hoyt, G.D. and W.L. Hargrove. 1986. Legume
Brewer, M.W. 1993. Chemical cultivation using cover crops for improving crop and soil
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Cotton Conf. National Cotton Council of America,
Memphis, TN. Touchton, J.T., D.H. Rickerl, R.H. Walker, and C.E.
Snipes. 1984. Winter legumes as a nitrogen source
Chase, L.W. 1942. A study of subsurface tiller f o r no-tillage cotton. Soil Tillage Res. 4:391401.
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