James J. Hoorman
Hoorman Soil
Health Services
What
value do cover crops bring to a farm field? As the old saying goes:
There are a 1000 ways to skin a cat! Please do not take that literally. I
came across two sources that try to put a value on cover crops for
their farms.
Rulon farms in Indiana have been doing no-till and
cover crops since 2005. They farm 5600 acres, 50-50 corn -soybean, using
no-till and about 90% of their acres have cover crops. This is a family
farm with one brother being a Purdue Economist. Since they believe the
benefits accrue over many years, they do a “whole farm” cost-benefit
approach (costs and benefits/acre are additive). The Rulon’s have used 4
different cover crop mixes using mostly spring oats, radish, rape, and
crimson clover (after early corn) or simply cereal rye after late corn.
Their average cost per acre for seed is around $22/acre. The cost for
seeding is another $13 for a total cost per acre of $35 (whole farm).
Cover
crop benefits are varied and additive. On fertilizer, they figure they
save 30# of potassium (K) and 20# phosphorus (P) worth about $22/A based
on cover crop tissue test. Since nitrogen (N) is variable, they avoid
counting that but they know there is some benefit to N from cover crops.
On corn, they gain 7 bushel per acre over the whole farm (14 bushel/A
on just the corn acres) @ roughly $5/bushel or $35. On soybean, about
2-bushel whole farm (4 bu./A) @$15 or $30/A. About every five years they
get a drought when the no-till and cover crops shine, they gain
30-bushel corn or about 6-bushel corn average @$5 or an average of
$30/A/year.
They terminate their cover crops early, but their soil
organic matter (SOM) levels have climbed. They estimate that SOM gains
them another 2.7 bushel of corn @$5 or $13.50 per acre over the whole
farm. They also figure they save 2 ton/A of soil by reducing soil
erosion, they put a value of $2.50 per ton (an extremely conservative
value) saved or $5/A. over the whole farm. Their annual total benefits
from cover crops are $135.50 minus the $35 for planting cover crops, or
roughly $100 per acre. Depending upon the government programs, those
numbers can be added in to this calculation. The Rulon’s numbers were
updated to 2022-2023 fertilizer and crop prices.
Alan Sundermeier
(retired Wood County OSU Extension) is the new director for the
Conservation Action Project (CAP) in Northwest Ohio. He collected local
cover crop residue data in Wood, Fulton, and Henry Counties this fall.
Alan sampled one farm with a sandy and sandy loam type soil that had 1.4
tons of biomass per acre and 1200# carbon with a carbon: nitrogen (C:N)
ratio of 20. This farmer used a cover crop mix with lots of clovers and
legumes and had 60# N, 11# P, 70# K, 20# calcium (Ca), 6# Magnesium
(Mg), and 3# Sulfur (S)/acre valued at roughly $105/acre or $75 per ton
of biomass based on current prices. There are a lot of assumptions in
this analysis but Alan estimates only 50% availability for N, 66% for P,
60% for K, and 40% for Ca-Mg-S fertilizer nutrients.
On two other
farms, higher clay contents and later planting, the numbers are not
quite as good due to less cover crop biomass. Farm #2 in Fulton County
had .6 tons crop residue, 500# carbon, C:N ratio of 21, 25# N, 7# P, 30#
K, 14# Ca, and 3# each Mg & S for a value of $44/Acre or $73/ton of
crop residue. This cover crop mixture had more grasses and over
wintering cover crops. The third famer in Henry County had only .4 Ton
biomass due to late planting 350# carbon but with a late planting, the
C:N ratio was 14 due to young, lush vegetation. He had 26# N, 5# P, 24#
K, 16# Ca, 3# Mg, and 2# S for a calculated value of $40 per acre or
$100/ton of crop residue. Since all these 9-11 way mixtures had over
wintering cover crop species, additional residue will be tissue tested
in the spring along with yield data next fall. For more information, see
the CAP website at https://capofohio.org.
Overall,
we know cover crops add value to a farm, but often trying to figure out
what that value actually is per acre per year is difficult to
calculate. Sometimes not all the benefits are obvious (wildlife
benefits, more butterflies, clean water, less farm stress, less labor,
less chemicals, less equipment, and more family time). Putting a value
on healthy food, healthy work, and healthy living may simply be
invaluable