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July 13, 2007: As a new farmer—new to both
rural living and Pennsylvania—I was glad to attend Pennsylvania’s
Cover Crop Research and Management Summit last month. I found
a tremendous amount of information about cover crops in sustainable
and organic farming systems.
My wife, Joan, and I purchased our 91-acre farm near Huntingdon,
Pennsylvania, in January 2005. We spent the next two years
moving from St. Louis, Missouri, upgrading some of the farm’s
infrastructure, and obtaining an organic crop certification.
At this point we are most interested in producing organic
vegetables and hay, and at some future date having an on-farm
produce market. I have also given some thought to growing
organic grain and forages to sell to the increasing number
of organic dairy farms in the area.
We want our farm to be both sustainable and organic. We are
engaged in constant discussion and debate on where we want
to go with this farm in terms of our mission and goals. We
also lack basic farming skills and experience, a situation
which puts our farm at risk. I’m looking for wisdom
in others’ experiences. To learn a bit about our challenges
this spring, see the sidebar “Our farm year so far.”
This planting season I moved in the direction of solving
a soil-fertility issue of low nitrogen in my commercial vegetable
garden. In reviewing seed catalogs, we saw cover-crop seed
mixes were being marketed as green manure to enrich the soil
with nitrogen and organic matter. My wife and I were drawn
to a spring-planted, green-manure mix of 60 percent field
peas, 25 percent oats and 15 percent hairy vetch.
We decided to create our own green-manure mix using chickling
vetch, forage peas and soybeans based on information from
a seed salesman from the Midwest. However, as we explored
this alternative and prepared to execute it, we realized how
little we knew about managing cover crops to assure us of
a successful outcome. We decided not to sow the early-season
mix until we understood things better. The summit looked like
a great way to learn about improving soil nitrogen with cover
crops.
Cover crop selection
Held at the Penn State University agronomy farm at Rock Springs,
the event turned out to be a great day for those of us who
wanted to use cover crops in sustainable farming systems.
Penn State and Rodale Institute staff paired up to give four
presentations.
Dave Wilson, agronomist at Rodale, and Ron Hoover of Penn
State discussed cover-crop species attributes and selection.
Cover crops serve multiple purposes, and their incorporation
into your crop rotation provides multiple benefits in a comprehensive
approach to soil fertility and quality issues. Dave
Wilson’s handout titled “Cover Crops for the Northeast”
is a must-read resource on this
topic. [ Can we link to this? ]
Cover crops discussed or displayed in research plots included
rye grass, winter rye, sweetclover, sorghum-sudan grass hybrids,
red clover, hairy vetch, alfalfa, berseem clover, crimson
clover, white clover, peas, forage radish, oilseed radish,
daikon radish, oats, buckwheat, bahiagrass, sun hemp, mucuna,
teff, wheat, fava and bell beans, rapeseed, canola, millets
and lab lab. What I heard and saw made me aware of the many
cover crop options and their contribution to improving soil
quality, combatting weeds, managing pests and fighting crop
diseases.
The summit presentation by Wilson and Hoover gave me, a new
organic planter, an understanding of the why, what and when
of cover crops I should implement in my crop rotation in order
to improve my soil. I’m planning to use a cover crop
in my commercial garden after the snow peas and English shell
peas finish in mid-July, which will probably be a non-legume
such as rye. In my sweet corn plots, as the harvests are completed
sequentially between late July September, I plan to use hairy
vetch to rebuild my nitrogen for the next season.
Monitoring soil change
Mary Barbercheck, a Penn State professor of entomology, demonstrated
four low-tech ways to monitor changes in soil quality:
Use test meters and test strips to monitor
soil pH. The optimum range for most crops is between 6 and
7.5.
Use test strips to monitor soil nitrate
which will show the amount of nitrogen in nitrate form that
is available for use by plants.
Use a plastic barrier, water, a watch and
a form that holds at least an inch of water to monitor the
soil’s ability to take in water through the surface
over time (infiltration). One inch of water soaking in per
30 minutes is considered to be moderately rapid.
Assess how easily an object can be pushed
into the soil to monitor soil compaction. A penetrometer will
actually measure the force being applied.
Also key to success is keeping records of these soil tests
to have them for comparison later. In her presentation, Barbercheck
introduced a soil-quality health card which I plan to use
in my record keeping. This card lists items that can be assessed
without the aid of technical or laboratory equipment, including
soil tilth, compaction, water infiltration and generation,
erosion, subsurface cover, soil life, soil organic matter,
plant growth and plant roots.
There are three assessment description ranges (good, medium
and poor). Within the ranges a numbered rating can be applied
for more detail. Using a comparative approach, I can learn
a lot about my soil. You can easily compare fields on your
own farm or compare your fields with other farms' fields.
For example, I could observe and assess that the Penn State
fields would have a “good” rating compared to
the same indicators in my farm fields—which I would
place in the “poor” range.
Keeping natural N where it belongs
Robert Gallagher, an associate professor of cropping systems
at Penn State, along with his students Justine Cook and Anna
Starovoytov, presented management alternatives to improve
nitrogen utilization from hairy vetch. They explained the
need to manage excessive nitrogen from hairy vetch to prevent
nitrogen leaching and environmental damage. This was surprising
to me, because I wasn’t aware that N leaching was possible
from a cover crop. I realized I needed to know: How much N
does the vetch produce? What makes it leach away? How can
you have a great crop of vetch, and keep it from becoming
a pollutant?
Under good growing conditions and proper management, hairy
vetch can supply enough N to even heavy nitrogen feeders.
As a legume, it’s able to fix nitrogen from the atmosphere
and convert it into a form that’s available to other
plants. Vetch is managed to grow long enough to produce a
huge amount of biomass, since the residue of the above-ground
plant contributes significant nitrogen, in addition to what’s
in the nodules on the roots.
Having a good crop of vetch depends on timely planting within
the late summer to early fall sowing window, the weather in
winter and spring, and the sowing date of the cash crops that
follows. Heavy rains in the fall and spring can cause soil
nitrogen to leach. Rye or other grains planted with the vetch
can act as a “catch crop” for the nutrient nitrogen.
These non-legumes take up nutrient N and prevent it from moving
downward to below the root zone where it can become a pollutant.
Got your weed management covered?
Timothy Leslie briefed us on beneficial macro-organisms relative
to soil quality and weed suppression. He explained that some
beetle species, known as granivores, feed exclusively on weed
seeds, and demonstrated a low-tech insect trap he uses to
assess and identify insect populations in the field.
Bill Curran, a professor of weed science, with team members
Ruth Mick, Steven Mirsky and Matt Ryan, discussed cover crops
in weed management. The highlights of their presentation were
the mechanical tactics of mowing and the use of roller/crimper
technology to create a barrier of mulch and residue for weed
suppression.
I gained much insight about how cover crops will help us
achieve our productivity goals in the coming years by improving
soil quality and helping us manage weeds. 
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