This document summarizes a study on reducing climate change and water quality impacts from grain production in Maryland's Eastern Shore. The study tested winter cover crops and reduced nitrogen fertilizer rate treatments. Key findings were that in a dry year, cover crops reduced fall nitrous oxide emissions and tile drain nitrate levels, while reduced nitrogen rate lowered emissions and nitrate without affecting yields. In a wet year, cover crops reduced nitrate but not emissions, and reduced nitrogen led to lower yields with minimal effects on emissions and nitrate. Future work involves using measurements to validate simulation models and estimate broader regional impacts to facilitate environmental market transactions.

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Reducing Climate Change and Water Quality Impacts
from Grain Production on Maryland's Eastern Shore
Jon Winsten, Tom Fisher, Rebecca Fox,
Anne Gustafson, Jim Lewis, Neville Millar

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Background
• Crucial issues: Climate change and water quality
• Nitrous oxide (N2O) has 310 times the radiative
forcing of carbon dioxide (CO2)
• N2O is 7% of U.S. GHG emissions
– 73% is from agriculture
• Agriculture is the leading source NPS pollution
to ground and surface waters in the U.S.

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Background
• Feeding 9 billion people by 2050.
• Regulations decrease productivity and increase
costs.
• Environmental markets provide prices for
“externalities” and can result in efficient
outcomes.

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Choptank River Watershed

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Research Site

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Research Treatments
• Winter cover crops
• Reduced N rate (80% of UMD recommendations)
• Conservation rotation
– 80% N rate on corn
– 80% N rate on winter wheat
– Soybeans
– Barley cover crop

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Nitrous Oxide Sampling

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Nitrous Oxide Sampling

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Water Quality Sampling

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Water Quality Sampling

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Nitrous Oxide Sampling Schedule
Treatment: 80% N on Corn
date purpose
20130129 winter fluxes
20130225 winter fluxes
20130408 spring fluxes prior to biosolids
20130513 3 days after biosolids
20130517 7 days after biosolids
20130530 7 days after planting corn, starter
20130614 10 days prior to side-dress
20130627 3 days after side-dress
20130702 8 days after side-dress
20130709 15 days after side-dress
20130828 2 weeks prior to harvest
20131007 3 weeks following harvest
20131106 7 weeks following harvest

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Nitrous Oxide Sampling

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Results:
Winter Cover Cropping
22 3.7
lbs N acre-1 (Nov-Mar)
36 32
lbs N acre-1 (Dec-Mar)

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Results:
Reduced N Rate
45 29
lbs N acre-1 (Nov-Mar)
32 30
lbs N acre-1 (Dec-Mar)

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Costs and Revenues
• Cover Crops
– Potential Revenues
• Conservation payment: $70/ac
• Carbon credits: 1MT CO2e/ac @ $10/MT = $10/ac
• WQ credits: 10 lbs N/ac @ $5/lb = $50/ac
– Costs
• Seed: $40/ac
• Planting: $8/ac
• Herbicide: $14/ac
– Profit = $130 - $62 = $68

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Costs and Revenues
• 80% N Rate
– Potential Revenues
• Carbon credits: 0.2MT CO2e/ac @ $10/MT = $2/ac
• WQ credits: 8 lbs N/ac @ $5/lb = $40/ac
– Costs
• Fertilizer: saved 40lbs N/ac @ $0.52/lb N = -$20.80
• Yield loss: 30 bushels/ac @ $3.75/bu = $112.50
– Profit = $42 - $91.70 = $-49.70

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Initial Conclusions
– Dry Year:
• Cover crops reduced fall N2O fluxes winter/spring
tile drain NO3
• Reduced N rate reduced N2O and NO3 and did not
affect yields
– Wet Year:
• Cover crops did not reduce N2O, but did reduce
NO3
• Reduced N rate lowered yields and had minimal
effect on N2O and NO3

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Future Work
– Use measurement data to cal/val simulation
models
– Use models to estimate impacts for farmers in
Eastern Shore region
– Facilitate farmers’ transactions in
environmental markets