Soil is at root of good crop production, but all too often, as the
saying goes, it “can’t get no respect.” As vegetable growers, we
push it around, drive all over it, leave it exposed to the elements, and
feed it junk food. In other words, we treat it like dirt.
Good soil deserves better. Afer all, it’s miraculous stuff--tens
of thousands of years old, chock full of nutritious minerals, able to retain
as well as drain water, and home to millions of micro-organisms in every
Being a little nicer to this agricultural super-hero we call soil
is a smart move that will pay off in subsequent years, and for future generations.
The basic approach to soil stewardship is simple enough: avoid harmful
practices that cause erosion and compaction, and engage in good practices
that add organic matter and improve soil structure. Here’s a short summary
of how to maintain, and even improve, your soil’s health.
Don’t give away the store. While it takes millennia to make topsoil,
it only takes moments to lose it. Blowing wind and flowing rainfall are
the agents of erosion. To protect against them, avoid nudity. Cover up
the soil every chance you get. Sow the alleyways to a cover, and put on
a cover crop whenever harvests are complete. In fields that finish up while
it’s still summer, buckwheat is good for a quick month or two of
ground cover before fall. After fall harvests, sow oats, rye or other small
grains ASAP so your fields will be protected over winter.
Take a break. By working every field, every year, you may make some
more money now, but it will cost you later as soil quality deteriorates.
A good vegetable crop rotation periodically takes land out of cash crop
production, ‘resting’ it with a soil improving crop. For multi-year rests,
most any kind of perennial hay crop will do. For a single year off, a sequence
of cold-weather and warm weather cover crops, like field pea / buckwheat
/ winter rye can be used. Rigorous crop rotation helps reduce disease,
insect, and weed pressure as well.
Breathe deeply. If you squeeze the air out of soil by performing
tillage when it’s too wet the resulting compaction will reduce root growth
and prevent drainage, lowering crop yields for years to come. Frequent
use of heavy equipment also compacts soil. Using permanent roadways in
your fields can help avoid compaction from vehicle traffic. If you’ve already
got compaction, subsoiling may help, as can certain cover crops. Research
in upstate New York has shown that Sudangrass as a summer cover crop or
perennial ryegrass as a fall / winter cover crop are good choices for remediation
of compacted soil. The combined use of subsoiling and cover crops provided
additive benefits to the soil.
Promote physical fitness. Soil structure is the physical condition
of the soil. It’s so important that we’ve got lots of ways to say it. A
soil with good structure has tilth, it’s friable, crumbly, even mellow.
A soil in good physical condition is porous and easy to work. It has
plenty of aggregates, which are tiny clumps of stuck-together soil minerals
and organic matter. Avoiding erosion and compaction can help protect soil
structure, but adding organic matter on a consistent basis is the key to
maintaining or improving the physical condition of your soil.
Eat a balanced diet. Growers pay a lot of attention to the mineral
nutrients in soil that crops need, like N-P-K. When they’re in short supply,
fertilizer is applied. But carbon should also be added to the soil. Carbon
isn’t considered a fertilizer nutrient since crops get it through photosynthesis.
However, the soil is full of microbes that can’t photosynthesize, and they’re
hungry for carbon. These microbes are key to improving soil structure because
they’re messy eaters, and they leave a lot of slimy by-products around
which help bind soil particles together. So, while they eventually consume
most of the carbon that’s applied to the soil, along the way they help
make soil aggregates. Compost, cover crops, and green manure crops are
all good carbon dishes to serve your microbial buddies. Just don’t ask
them over to dinner.
Keep an eye out for trouble. Your friendly Land Grant University
has been subsidizing the cost of soil tests and providing localized fertilizer
recommendations for many decades. Take advantage of this opportunity to
monitor soil fertility. In addition to pH and major nutrients, get some
extra things tested like trace elements and soil organic matter. Test every
field on your farm, at least every 3 years. Growing crops without soil
tests is like flying a plane without radar. Sure, you can do it, but if
you don’t know where you’re going, you’ll probably get there.
For more information on this topic, see ‘Building Soils
for Better Crops’ at: hwww.sare.org/Learning-Center/Books/Building-Soils-for-Better-Crops-3rd-Edition.