January 2019 - 24

MSUE VEGETABLE NOTES
Tillage, cover crops' long-term effects studied
Relative yield
By Daniel Brainard and Zachary Hayden
Michigan State University
Most of us are too busy in the summer
to think much about the long-term
consequences of our management
practices. But with snow on the ground,
this is perhaps a good time to reflect on
potential investments in cover crop and
tillage practices that may be beneficial
for ensuring the long-term health of our
farms. Here we provide a quick update on
a long-term study, conducted on sandy
soils in southwest Michigan, that we hope
will provide some food for thought.
Long-term trials. To help understand
the impact of tillage and cover
cropping practices over time, we have
been conducting a long-term field
experiment at two sites on sandy soils
in southwest Michigan since 2009.
The study compares practices that are
likely detrimental to soils (full-width
tillage without cover cropping) to those
likely to improve soils (strip tillage
with cover cropping). Our full-width
tillage treatment is accomplished with a
moldboard plow + field cultivation. For
strip tillage, we use a Hiniker 6000 strip
tiller equipped with a shank, offset disks
and a rolling basket to prepare a 10-inch
Plow
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140
120
100
80
60
40
20
Strip tillage
Plow + Rye
Strip tillage + Rye
Sweet corn
Snap beans
wide by 10-inch deep strip for planting,
while leaving approximately 20 inches
of undisturbed soil between crop rows.
Cover crops in the study have included
winter rye, or a rye-vetch mixture. These
tillage and cover crop treatments have
been applied in the same plots every year
for the past 10 years, with only the crop
varying between years. Each year, we
grow two crops (one at each site), within
Cucurbits
Source: MSU Extension
a three-year rotation of sweet corn, snap
beans and a cucurbit crop.
Lessons after 10 years. Figure 1
provides an overall summary of the
" relative yield " for each of the rotational
crops averaged across the 19 site-years
of our trial. The relative yield is simply
the yield observed for each practice as
a percentage of the " control " treatment
(plow with no cover crop). Based on this
data, and our observations, here are a
few of the key lessons learned:
* Strip tillage has had little or no
effect on crop yields. In sweet
corn, strip tillage appears to have
boosted yields by approximately
4 percent on average over seven
site-years. In contrast, strip tillage
has not had consistent effects on
snap beans or cucurbit crops.
Since strip tillage is generally less
expensive and time-consuming
than full-width tillage, and
may improve soil quality over
time (more on that below), the
benefits in corn, and the lack of
significant yield penalty in other
crops, is encouraging.
* Rye cover cropping has
improved yields in cucurbit
crops but has been detrimental
in sweet corn. Averaged over six
site-years, rye cover cropping
(in full-width tillage treatments)
improved cucurbit yields by
14 percent. In contrast, winter
rye provided no benefit in snap
beans, and appears to have
reduced yields in sweet corn
by about 5 percent on average.
Rye provides some benefits for
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24 | VegetableGrowersNews.com
Percent of control
http://www.VegetableGrowersNews.com
January 2019

Table of Contents for the Digital Edition of January 2019
