- J. Sadler Richards, Conservation Management Systems - A Division of
Ecologistics Ltd., Lucan, Ont.
Evaluation Summary (Tech. Transfer Report Summaries)
View / Download Final Report [122 KB pdf]
Associated SWEEP/LSP Research
Completed: January, 1992
cover crop, red clover, erosion control, conservation cropping, residue
cover, chemical kill, mechanical kill, corn, chisel plow, no-till
In 1987-90 seven trials were conducted in Middlesex and Huron Counties
in southwestern Ontario to study the effect of time and method of control
of a red clover cover crop on the growth and yield of corn. Drought conditions
during late spring and summer in 1988-89 affected the performance of the
cover crop and main (corn) crop. Excessively moist conditions in the spring
of 1990 affected plant emergence and final plant stand especially on the
spring tillage treatment.
Results from three years of study indicate that in general those treatments
which included the use of a mechanical method for controlling red clover
resulted in grain corn yields approximately 11% higher than those achieved
with the average no-till treatments, although the effect was not always
statistically significant. However, this may be related to the previous
crop stubble. Those sites which had red clover underseeded to winter wheat
reported the greatest reduction in grain corn yield under no-till conditions
compared to sites which had oats or oats and barley as the stubble crop.
Under mechanical methods of red clover control the amount of soil surface
residue cover left after planting was unacceptable from an erosion control
standpoint. The chemical kill treatments provided somewhat lower corn grain
yield with excellent residue cover remaining after planting. The mechanical
kill treatment using the chisel plough produced yields which were similar
to the October chemical kill treatments and may he used as an alternative
to using the moldboard plough.
The amount of dry matter collected from each of the treatment plots was
related to the date and method of control of the red clover. The chemical
treatment applied in May recorded the greatest amount of dry matter after
planting followed by the April timing whereas the least amount (if any)
was collected on the moldboard plough treatments.
Results of the rainfall simulation indicated that the mechanical kill
treatments (moldboard and chisel plough) recorded significantly higher runoff
volumes, soil losses as well as total phosphorus losses compared to either
of the chemical kill treatments (October and April). The difference in the
results obtained for the chemical kill treatments for the above parameters
were not significant indicating that the time of the red clover kill did
not affect the erosion control of these treatments. In addition, no significant
differences between the chisel and moldboard plough treatments were reported
for these parameters.
(From Technology Transfer Report Summaries - A. Hayes, L. Cruickshank,
This three year study evaluated the effects on residue levels and corn
performance of various chemical and mechanical kill methods and times of
kill, of a red clover cover crop.
Treatments consisted of chemical kill, mechanical kill with moldboard
plow, and mechanical kill with chisel plow in either fall or spring. The
chemical kill treatments were no-till planted. Measurements taken were soil
residue cover, red clover above ground dry matter, corn plant emergence,
corn plant height, 50% silking date, corn yield and associated factors.
At all sites, chemical kill plots had significantly more residue remaining
(33-84%) after planting than the mechanical kill plots (3-26%). The level
of residue on the moldboard plots was not high enough to provide sufficient
erosion control. Spring chemical kill treatments resulted in more residue
than fall kill. For each treatment, the amount of red clover dry matter
was related to the date of kill (later kill, more dry matter). Chemical
kill plots had significantly less soil loss than mechanical kill treatments.
Corn emergence was low at 14 days after planting (DAP) for chemical kill
in May, while fall moldboard and fall chemical kill had higher emergence.
Differences were less significant at 21 DAP, but in general fall kill treatments
had more plants emerged. At most sites, moldboard treatments had taller
plants at the 2-3 and 6-7 leaf stage and also reached 50% silking sooner.
Corn yields were considerably lower on chemical kill treatments than
on mechanical kill treatments. Yields also tended to be higher and grain
moistures lower for earlier killed treatments.
The study's authors believe that there may be some allelopathic effects
of the previous year's cereal stubble or the red clover residue on the corn.
Insects and slugs were also more of a problem in the no-till treatments.
These factors may have contributed to the lower yields in the chemical kill
A red clover cover crop killed in the fall by chemical means or by chisel
plowing is effective in reducing soil erosion and only reduces corn grain
yields by a small amount, if at all.
The study was done on seven different sites, with up to four different
planters, up to four different corn hybrids, four different previous crops
and there was no check without red clover for the chemical kill treatments.
These variables could have had a significant effect on the results of the
study. The yield data shows an 11% reduction was experienced after winter
wheat (chemical kill) but after oats, barley or red clover hay the chemical
kill yields ranged from a 1% reduction to a 9% advantage. The straw was
removed from the spring cereal crops and left on the winter wheat fields.
There is a stronger case for the authors' conclusions applied to winter
cereals than spring cereals. The hand harvest yields were done using the
10 average cob method which is not as accurate as shelling all the cobs.
There may not be a need for a cover crop, if corn is no-tilled into wheat
stubble, as the ground is well protected to begin with. Why complicate matters
by planting red clover?
SWEEP Report #12 - Choice and Management of
Cover Crop Species and Varieties for Use in Row Crop Dominant Rotations
SWEEP Report #27 - Cereal Cover Crop Study
SWEEP Report #29 - The Effect of Organic Mulches
on Soil Moisture and Crop Growth
SWEEP Report #32 - Optimal Herbicide Use in
Conservation Tillage Systems
SWEEP Report #43 - The Use of Cover Crops for
SWEEP Report #52 - Field Scale Tests of Cover
Crops I and II
SWEEP Report #57A - Field Testing of Cover
Crop Systems for Corn and Soybean Production
LSP7005 - Crop Rotations and Cover
Crop Effects on Erosion Control, Tomato Yields and Soil Properties in Southwestern
LSP7009 - A Cover Cropping Strategy
for First Early Potato Production
Future Research: ( ) indicates reviewers suggestion for
priority, A - high, C - low.
(A) The authors recommend further research, including monitoring the
amount of nitrate nitrogen being contributed to the corn crop from the red
clover and initiating field scale studies on the fall kill treatments.
Thursday, May 19, 2011 02:59:05 PM