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.
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