Southeastern U.S. Vegetable Crop Handbook - 2023 - 11

MINIMUM TILLAGE FOR VEGETABLE
PRODUCTION
The development of various types of tillage practices was an
integral part of the evolution of modern farming practices. Tillage
is helpful in crop production systems for purposes of weed
management, incorporation of amendments such as lime and
fertilizer, buri al of crop residues to facilitate other field operations,
disease management, and the preparation of a seedbed
that is conducive to crop establishment. While the use of tillage
practices provides a number of benefits to crop producers, researchers
have also learned that the soil disturbance associated
with tillage has some drawbacks. In a nutshell, tillage over time
results in the degradation of several soil properties that are important
to crop productivity.
One of these properties is organic matter content. Organic
matter is important because it contributes appreciably to the
water and nutrient holding capacity of soil and to the maintenance
of a desirable soil structure. These soil properties, in turn,
allow soil to better support the weight of equipment and workers.
In warm southern climates the loss of organic matter due to
tillage is even more pronounced than in cooler climates. Tilled
soil is also less hospitable to a variety of soil organisms including
microbes, insects, and other small animals. When present
in adequate numbers these are beneficial for various reasons.
When minimum tillage is used, soil structure is improved by the
release of exudates of various organisms that glue soil particles
together into larger, more desirable aggregates. Plant roots benefit
from the increased presence of pore spaces in the soil such as
earthworm channels, and plant diseases may also be reduced by
the increased diversity of soil microorganisms.
Adoption of minimum tillage in vegetable production is
possible but requires careful planning and preparation. Making
a transition to minimum tillage will affect several vegetable
production field operations. For example, one common objective
of minimum tillage is to retain crop residues on the soil
surface. These residues are beneficial for reducing soil erosion
but also may interfere with the seeding of crops, particularly
small-seeded vegetable crops. Similarly, cultivation, often an
important measure for controlling weeds in vegetables, may
require different equipment than what the farmer is able to use
in conventionally tilled fields. In general, it may be best to start
with those vegetables that are grown similarly to agronomic
row crops or to use crops that can be established by transplanting
through crop residues. Row crop examples include sweet
corn and cowpeas. Examples of vegetables that are easily transplanted
include tomato, pepper, squash, and watermelon.
Growers interested in adopting minimum tillage practices
should begin by learning about the practices currently employed
by agronomic crop producers and others who grow vegetables
using reduced tillage. One such practice is to limit tillage and
seedbed preparation to a narrow strip where the crop will be
planted. This may be done in combination with the use of cover
crops that are killed by rolling and crimping prior to tilling the
strip. This method has been used successfully for vegetables
such as tomatoes and cucurbits.
2023 Vegetable Crop Handbook for Southeastern United States
COVER CROPS
Many soils that are not productive due to poor physical properties
can be restored and made more productive through the
continued use of cover crops. Cover crops can provide many
benefits to soils that include reducing the buildup of soilborne
disease and arthropod pests, increasing soil organic matter, suppressing
weeds, improving soil structure, promoting beneficial
soil microorganisms, improving nutrient cycling, and reducing
soil erosion. Each cover crop can offer different potential benefits
to a production system and not every cover crop will work
for each grower's intended purpose.
Many cover crops can reduce or limit the build- up of soilborne
disease and insect pests that damage vegetable crops.
Prevalent disease and insect pressure should be considered when
selecting a cover crop as some cover crops could increase the
severity of these issues. In some cases, specific cultivars of cover
crops can differ in their host status to various plant-parasitic
nematodes. For example, 'Cahaba White' common vetch is suppressive
to southern root- knot nematodes while 'Vantage' common
vetch is susceptible to southern root-knot nematode.
With intensive cropping, working the soil when it is too wet
and excessive traffic from using heavy equipment will contribute
to damaging soils. These practices cause soils to become hard
and compact, resulting in poor seed germination, loss of transplants,
and shallow root formation of surviving plants. Such soils
can easily form crusts on the surface, become compacted, which
make them difficult to irrigate properly. Combined, these practices
will yield negative consequences for your soil; poor plant
stands, poor crop growth, low yields, and loss of income. In
some cases, sub-soiling in the row might help improve aeration
and drainage, but its effect is limited and short term. Continued
and dedicated use of cover crops will aid in preventing these
conditions. It may take several years of continued use to observe
some of the benefits that cover crops can provide to soils.
Cover crops can also be planted in strips for wind protection
preceding the planting of the cash crop. Annual rye seed
ed before November can be a good choice for use in wind protection.
Cover crops reduce nutrient loss during the winter and
early spring. Cover crops may deplete the soil moisture. If this
is a concern, be sure to disk or plow the cover crops before soil
moisture is depleted.
Seeding dates suggested in the following section are for the
central part of the Southeastern United States and will vary with
elevation and northern or southern locations. For state specific
recommendations for planting dates for cover crops, consult
your local Extension office.
Summer Cover Crops
Summer cover crops can be useful in controlling weeds,
soilborne diseases, and plant-parasitic nematodes. They also
provide organic matter and can improve soil tilth while reducing
soil erosion. There are many potential summer cover crops
available, but you will need to find one that will work well in
your area and fit into your overall production scheme. Sudex
(sorghum-sudan grass cross; do not allow to exceed 3 ft. before
mowing), southernpeas (cowpeas), millet, and Lab Lab are
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Southeastern U.S. Vegetable Crop Handbook - 2023

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