AGRICULTURE
EXTENSION
AY-363-W
Indiana Soil and Water
Authors
Jennifer Woodyard and
Eileen Kladivko
Four Strategies to Improve
Your Field’s Soil Health
What Is Soil Health?
e denition of soil health is changing.
For many decades, the study of soil health
emphasized soil’s physical and chemical
properties. Today, soil scientists strive to
include biological aspects as well, since
many of the processes that inuence soil
occur because of living organisms.
is shi reects the desire of farmers,
researchers, and agricultural professionals
to protect the long-term sustainability of
soils, water, and cropping systems. is
publication provides four basic strategies to
help improve the health of your soil.
ese four strategies are based on four basic
soil health principles outlined by the USDA-
Natural Resources Conservation Service
(NRCS):
1. Minimize soil disturbance
2. Keep soil covered
3. Maximize plant diversity
4. Maximize the period of living root
growth
When you consider how to improve your
soil’s health, keep in mind the natural
characteristics of your soil, including its
texture, natural drainage class, and slope.
Purdue Agronomy
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AY-363-W • Four Strategies to Improve Your Field’s Soil Health
Because these factors are oen unique to your location,
soil health can mean dierent things. In other words,
healthy soil in northern Indiana is going to be dierent
from healthy soil in southern Indiana due to the
inherent nature of the soil. Characteristics like these can
inuence the timing and degree of your soil’s response
to the strategies we describe in more detail below.
Key Soil Health Components
What does a healthy soil encompass? Here are some of
the important players in soil health.
Soil aggregates are a fundamental concept in soil
structure. Aggregates are groups of soil particles that
bind to each other more strongly than to other particles.
ey form pores that help soils retain water and air. Soil
aggregates can change quickly. Within a few years of
starting conservation practices (such as implementing
no-till systems and planting cover crops), aggregates can
change in size and stability.
Well-structured soils allow for adequate aeration, water
inltration, and root penetration and growth. Well-
structured soils also resist erosion and compaction. We
oen think of aggregates just as one of soil’s physical
properties, but biological organisms inuence this
structure. Earthworms, mycorrhizal fungi, plant roots,
and organic matter all inuence the ways soils form
aggregates.
When earthworms are present in a system, they create
tunnels. Later, plants can use these tunnels as root
channels, allowing roots and water to penetrate deeper
into the soil prole. Earthworms also leave behind casts,
which are rich in nutrients. Mycorrhizal fungi form
benecial relationships with plants by bringing water
and nutrients, particularly phosphorus, to a plant in
exchange for energy in the form of carbon. ere are
many dierent “good” soil microorganisms that help
break down residue, recycle nutrients, and combat the
“bad” pathogenic microorganisms that might negatively
inuence your cash crop growth.
What you plant can also inuence biological activity
in your soil. Introducing plant diversity into your
system is a natural way to control weeds and pests,
including pathogenic microorganisms. Diversity can
increase nutrient and water use eciency, introduce
dierent root types and residue, and reduce stress on the
cropping system.
Diverse root types and residue may reduce your soil’s
risk of erosion. Some plants decompose faster than
others, so where erosion is a concern, you may want
to consider introducing a plant that decomposes more
slowly and keeps the soil covered longer. Soil microbial
communities thrive on diverse residue produced by
various plants. As you add diverse plants, healthier
soil for agronomic purposes develops. at’s because
dierent plants are able to target a broader range of
soil resources than a monoculture system can target.
Monoculture systems may exhaust certain soil resources
more quickly and require additional inputs to maintain.
Organic matter plays a big role in soil health. Changes
in organic matter content do not occur quickly, and it
may take several years to see an appreciable dierence,
but increasing your soil’s organic matter will improve
its overall health. Organic matter largely contributes
to a soil’s cation exchange capacity (CEC), and organic
matter helps soil hold nutrients and water for plant use.
Soil microbes decompose residue into organic matter
and eventually transform it into mineralizable nutrients
for plant uptake.
The Four Strategies
e four strategies for improving your soil’s health are
not an all-inclusive list. Rather, these strategies provide
a good base to improve overall soil health. Many of the
strategies we discuss are connected and act together to
improve soil health.
1. Practice No-Tillage/Strip-Tillage
Reducing tillage to either no-till or strip-till minimizes
disruptions to soil aggregates by not breaking them up
continuously and forcing the system to restart (Figure
1). Minimal tillage maintains natural aggregates, one
of the key components of soil health, and helps prevent
loose soil particles from washing or blowing away easily.
Residue decomposes more slowly under a reduced
tillage system for several reasons. One reason is that
fewer aggregates are broken up with less intensive tillage,
so less organic matter is exposed to decomposition.
Second, reduced tillage can make soil temperatures
slightly cooler. Lower temperatures help organic
matter accumulate, because the residue is not broken
down as quickly. Reducing tillage can increase soil
organism diversity and activity, another one of the key
components of soil health. Reduced tillage does not
disrupt earthworm burrowing and helps protect the
network created by mycorrhizal fungi that connects
them to their host plant. Leaving residue on the soil
surface also acts as a barrier against raindrops and wind
that could cause erosion.
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AY-363-W • Four Strategies to Improve Your Field’s Soil Health
2. Add More Crops to Your Rotation
Corn-soybean or continuous corn rotations dominate
the Midwest landscape. In the short-term, these systems
yield in abundance and provide good economic returns.
However, a strong strategy for long-term resiliency
includes increasing plant diversity in your system.
Adding winter wheat in your rotation aer soybeans
is a fairly simple way to increase plant diversity, a key
component of soil health. Wheat’s early harvest also
oers a longer window of opportunity to establish
cover crops and add another layer to the crop rotation
(Figures 2 and 4).
Another potential option in some areas is double-
cropping soybeans aer wheat harvest. Whether you
use cover crops or another cash crop, keeping the soil
covered as long as possible benets overall soil health.
Pick what ts best in your operation and budget.
3. Include Cover Crops
Cover crops are becoming more widely adopted, but
many farmers still have questions about their usefulness.
ere is no one-size-ts-all solution to cover crops,
but a good place to start nding more information is
Managing Cover Crops: An Introduction to Integrating
Cover Crops into a Corn-Soybean Rotation (Purdue
Extension publication AY-353-W), available from the
Education Store, edustore.purdue.edu.
Cover crop roots improve soil aggregation and reduce
erosion. Cover crop residue also reduces the impact of
raindrops on the soil surface and serves as a habitat and
food source for soil microbes. As organisms decompose
the residue, nutrients are released back into the soil.
Organic matter, a key soil health component, can
increase over a longer period as residue is added back
into the system. Combining no-till and cover crops
is a great way to keep your soil covered, minimize
disturbance, maximize living root growth, and maximize
plant diversity.
Cover crops can also help manage nutrients in the eld
by scavenging nitrogen from the soil during typically
fallow months (Figure 3). In the winter (aer you
remove the cash crop) and in the early spring (before
planting) are periods when you usually see the most
loss of soil nitrogen. Cover crops can prevent some of
this loss and recycle nitrogen in the system, eventually
releasing the nitrogen from the dead residue as soil
organisms begin the decomposition process.
Choosing species that die in the winter (“winter kill”
species such as oats and radish) rather than species that
overwinter (such as cereal rye and annual ryegrass)
will make a dierence in the amount of soil nitrogen
scavenged and the timing of its release.
Figure 1. Planting corn into no-till cover crop residue. Photo
provided by Edwin Remsberg and USDA-SARE.
Figure 2. A 14-species cover crop mix planted after wheat harvest.
Photo by Jennifer Woodyard.
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AY-363-W • Four Strategies to Improve Your Field’s Soil Health
4. Manage Nutrients
Nutrient management goes hand-in-hand with the rst
three strategies we discussed. You may need to adjust
your fertilizer applications aer switching to a reduced
tillage system, adding a cash crop, or implementing
cover crops in your rotation.
As organic matter increases, you may see an increase
in your soil’s ability to hold nutrients longer. Keep your
local fertilizer dealer in the loop as you make changes to
your system, so they can give you recommendations to
t your specic needs.
Growing cereal rye before planting corn is not
recommended for novice cover crop growers, because
you may need to apply more of your nitrogen with the
planter to get the corn o to a good start. Over-applying
fertilizers can reduce mycorrhizal fungi’s natural ability
to scavenge nutrients for plants and can harm some
species’ abilities to colonize in the future.
Figure 3. Cereal rye cover crop growth in the spring before plant-
ing at Southeast Purdue Agricultural Center. Photo by Jennifer
Woodyard.
Figure 4. This photo shows several plants in a 14-species cover crop mix in October 2016. This mix (which was planted August 10) produced an
average of 4,600 pounds of biomass per acre at the Purdue Diagnostic Research and Training Center. Photo by Jennifer Woodyard.
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AY-363-W • Four Strategies to Improve Your Field’s Soil Health
Whenever you apply nutrients, regardless of whether
you use any of the other strategies discussed here,
it is important to keep the 4R principles of nutrient
stewardship in mind:
1.Right source
2.Right rate
3.Right time
4.Right place
More information about these principles is available
from the Nutrient Stewardship website, www.
nutrientstewardship.com/4rs.
A common practice is to test soil fertility once every
two years. Regularly testing your soil is an easy way to
take preventative measurements against over- or under-
applying the nutrients necessary for a successful cash
crop. Poor chemical health in your soil could indicate
poor overall soil health.
Conclusion
Any of the strategies listed in this publication can help
improve soil health over time. Because these strategies
overlap so much, you may be able to maximize the
benets by using several of them together. However,
when trying something new, it is usually best to start
small and learn how to properly manage the new
techniques before you expand the practices. Considering
the health of your soil is a great step toward building a
sustainable cropping systems future.
Additional Resources
No-Tillage Impacts on Soil Carbon, Nitrogen, and Water
Available from the Iowa State University Extension
Store, store.extension.iastate.edu
is fact sheet (CSCAP 114 2012) describes the benets
of no-tillage in a corn-soybean system and can be used
with a companion video. is publication is part of the
Climate and Corn-based Cropping Systems Coordinated
Agricultural Project (CSCAP).
Managing Cover Crops: An Introduction to Integrating
Cover Crops into a Corn-Soybean Rotation
Available from the Purdue Extension Education Store,
edustore.purdue.edu
is publication (AY-353-W) outlines an introductory
approach to integrating cover crops into a corn-soybean
cropping system.
Agronomy Technical Note: Recommended Cover Crop
Seeding Methods and Tools
Available from the USDA-Natural Resources
Conservation Service, www.nrcs.usda.gov/Internet/
FSE_DOCUMENTS/nrcs144p2_030986.pdf
is excellent publication describes cover crop seeding
methods that can be used in Indiana and the Midwest.
Midwest Cover Crops Council (MCCC)
www.mccc.msu.edu
is website includes cover crops selector tools that
allow you to choose your county and get seeding dates
for each cover crop. ere is a tool for agronomic crops
for many states, plus for a tool for vegetable crops for
Michigan. You can also get seeding rates by reading the
information sheet about your cover crop of choice. e
website includes a wealth of other information about
cover crops from around the Midwest.
Midwest Cover Crops Field Guide, second edition
Available from the Purdue Extension Education Store,
edustore.purdue.edu
is pocket guide (ID-433) was produced by the MCCC
and the Purdue Crop Diagnostic Training and Research
Center. e guide contains more detailed information
about selecting and managing cover crops and describes
common cover crops for our region. e descriptions
also include ranges of cover crop seeding rates.
Terminating Cover Crops: Successful Cover Crop
Termination with Herbicides
Available from the Purdue Extension Education Store,
edustore.purdue.edu
As the title suggests, this publication (WS-50-W)
describes how producers can eectively terminate cover
crops with herbicides to prevent them from becoming
weeds in the cash crop.
Soil Nitrogen Cycle
Available from the Iowa State University Extension
Store, store.extension.iastate.edu
is one-page publication is a great teaching resource
about the nitrogen cycle and can be used with
acompanion video. is publication is part of CSCAP.
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AY-363-W • Four Strategies to Improve Your Field’s Soil Health
Indiana Soil and Water: Tips for Environmentally Friendly
Phosphorus Applications in Indiana
Available from the Purdue Extension Education Store,
edustore.purdue.edu
ere is no single and universal answer to the question
of how and when to apply phosphorus (P) fertilizers.
However, this publication (AY-386-W) does propose
four basic P application management tips.
Purdue Manure Management Planner
www.purdue.edu/agsoware/mmp
is website has a free downloadable soware that helps
you create a manure management plan for crop and
animal feeding operations.
Find Out More
Find other publications in the Indiana Soil and Water
series in the Purdue Extension Education Store:
edustore.purdue.edu
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Aug 2017
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