Managing Cover Crops Profitably - Valley Crops Home

APPENDIX A
TESTING COVER CROPS ON YOUR FARM
by Marianne Sarrantonio
To find your best cover crops, you needn’t
become Dr. Science or devote your life to
research.It’s not hard to set up valid,on-farm tests
and make observations. Follow these steps:
A. Narrow your options. Aim for a limited-scale
trial of just two to five species or mixtures. You
can test the best one or two in a larger trial the
next year.
Unsure of the niche Start with small plots separated
from cropped fields and plant over a range
of dates, under optimal soil and weather conditions.
If you’re sure of the niche and have just two or
three covers to try, put the trial right in your
cropped fields, using a similar seedbed preparation.
This method provides rapid feedback on
how the cover crops fit into your cropping system.
Keep in mind management-related variables
could cause subpar results for an otherwise adequate
cover.
B. Order small seed amounts. Many companies
provide 1- to 10-pound bags if you give them
advance notice. If 50-pound bags are the only
option, arrange to share it with other growers.
Don’t eliminate a species just because seed
price seems high. If it works well, it could trim
other costs. You could consider growing your
own seed eventually, and perhaps even selling it
locally.
Be sure to obtain appropriate inoculants if
you’ll be testing legumes, which require speciesspecific
rhizobial bacteria so the cover can capture
and “fix”N efficiently. See Nodulation: Match
Inoculant to Maximize N (p. 92).
C. Determine plot sizes. Keep them small
enough to manage, yet large enough to yield adequate
and reliable data. Plots a few rows wide by
50 to 100 feet could suffice if you grow vegetables
for market. If you have 10 or more acres, quarteror
half-acre plots may be feasible,especially if others
in your area use similar species.
If you use field-scale machinery, establish fieldlength
plots. For row crops, use plots at least four
rows wide, or your equipment width. Keep in
mind the subsequent crop’s management.
D. Design an objective trial. Plots need to be as
uniform as possible, randomly selected for
each option you’re testing, and replicated (at
least two or three plots for each option).
If parts of the field have major differences
(such as poorer drainage or weedy spots), put
blocks of plots together so each treatment has
equal representation in each field part, or avoid
those areas for your trial.
Label each plot and make a map of the trial area.
E. Be timely. Regard the trial as highly as
any other crop. Do as much or as little field
preparation as you would for whole fields, and at
an appropriate time.
If possible, plant on two or more dates at least
two weeks apart. In general, seed winter annuals
at least six weeks before a killing frost.Wheat and
rye can be planted later,although that will reduce
the N-scavenging significantly.
F. Plant carefully. If seeding large plots with
tractor-mounted equipment, calibrate your seeding
equipment for each cover. This can prevent
failures or performance differences due to incorrect
seeding rates. Keep a permanent record of
drill settings for future reference.
A hand-crank or rotary spin seeder works well
for small plots getting less than five pounds of
seed.Weigh seed for each plot into a separate container.
1 lb./A is about equivalent to 1 gram/100
sq. ft., and 1 pound equals 454 grams.
Put half the seed in the seeder and seed
smoothly as you walk the length of the field and
back, with a little overlap in the spread pattern.
156 MANAGING COVER CROPS PROFITABLY