13 Agriculture
13.1 Introduction
Agricultural systems are major emitters of methane and nitrous oxide, both from livestock and croplands. Livestock emissions come primarily from enteric fermentation, the formation of methane in ruminants stomachs during digestion, and secondarily from manure emissions of both methane and nitrous oxides. Cropland emissions are predominantly nitrous oxide that is formed from biogeochemical processes related to crop-soil interactions and the direct application of synthetic fertilizers. Carbon dioxide emissions are a smaller share of agricultural emissions, arising predominantly from operation of agricultural equipment, liming of soils, and production of urea used for fertilizer.
13.2 Results
13.2.1 2021 county and subsector breakdown
Agriculture accounted for 2.1% of total emissions in the 11-county region in 2021. As expected, more rural counties produce a larger share of the agricultural emissions, with St. Croix, Pierce, Dakota, and Carver accounting for 77.1% of the regions agricultural emissions.
13.2.2 Baseline emissions
Regional agricultural emissions have decreased by 0% since 2005, potentially reflecting increased agricultural abandonment and suburban expansion in the region.
13.2.3 Emissions by gas type
The majority of agricultural emissions by weight are methane, but when accounting for the increased warming potential of nitrous oxide, CO2e are roughly equivalent. CH4: 48.2% N2O: 51.8%
13.3 CTU Estimates
City and township estimates represent county estimates apportioned to their in-boundary CTUs based on the ratio of CTU agricultural land to county agricultural land. As expected, cities and townships on the rural edge show highest agricultural emissions.
13.4 Summary
Methane production is largely tied to consumer food preferences, with enteric fermentation in cattle raised for meat and dairy production being the central driver of agricultural methane production. Nitrous oxide emissions also derive from livestock via manure emissions, both in managed systems and in manure that is applied to or leaches into soils. Crop production also accounts for a large percentage of agricultural nitrous oxide emissions via synthetic fertilizer production and the biochemical processes that delivers nitrogen to soils. Efficient agricultural techniques, particularly in crop management, can reduce the amount of nitrogen entering soil and therefore the amount that is volatilized into gaseous nitrous oxide.