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ARS Home » Plains Area » Sidney, Montana » Northern Plains Agricultural Research Laboratory » Agricultural Systems Research » Research » Publications at this Location » Publication #375834
Research Project: Ecologically-Sound Pest, Water and Soil Management Practices for Northern Great Plains Cropping Systems

Location: Agricultural Systems Research

Title: Net global warming potential and greenhouse gas intensity in organic and conventional wheat-based farming systems

Author
item Sainju, Upendra
item HATFIELD, PATRICK - Montana State University
item RAGEN, DEVON - Montana State University

Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2022
Publication Date: 9/22/2022
Citation: Sainju, U.M., Hatfield, P.G., Ragen, D.L. 2022. Net global warming potential and greenhouse gas intensity in organic and conventional wheat-based farming systems. Agriculture, Ecosystems and Environment. https://doi.org/10.1002/agj2.21168.
DOI: https://doi.org/10.1002/agj2.21168

Interpretive Summary: Net global warming potential is a parameter used by researchers to measure the net greenhouse gas emissions from an agroecosystem. It is determined by calculating the difference between all carbon dioxide sinks and sources from a system. Sheep grazing is a weed management practice commonly used in dryland cropping systems. An ARS researcher in Sidney, MT collaborated with researchers from Montana State University to compare net global warming potential due to a combination of sheep grazing in the organic crop production (no agrochemical inputs) versus a combination of minimum tillage in the conventional crop production (includes agrochemical inputs). Net global warming potential was lower with sheep grazing in organic crop production than minimum tillage in the conventional crop production due to increased soil carbon sequestration and absence of chemical inputs in the grazed organic system. Greenhouse gas emissions can be mitigated using sheep to control weeds in organic wheat-based cropping systems in the northern Great Plains.

Technical Abstract: Information on the effect of sheep (Ovis aries L.) grazing as a weed management practice on greenhouse gas (GHG) emissions in organic farming is scarce. The objective of this study was to evaluate sheep grazing during fallow periods in dryland organic farming (SGO) compared to minimum tillage with chemical inputs (MTC) in conventional farming on net global warming potential (NGWP) in three cropping sequences of a 5-yr crop rotation from 2013-2014 to 2015-2016 in the northern Great Plains, USA. Cropping sequences included lentil (Lens culinaris L.) after winter wheat (Triticum aestivum L.) (L-W), winter wheat after sweet clover (Melilotus officinalis L.) cover crop (W-C), and winter wheat after lentil (W-L); crop rotation was safflower (Carthamus tinctorius L.)/sweet clover cover crop–sweet clover cover crop–winter wheat–lentil–winter wheat. Carbon sequestration rate was greater in SGO with W-C than other treatments. The CO2 equivalent of N2O flux was greater in SGO with L-W than other treatments, except in MTC with L-W in 2014-2015 and 2015-2016. The CO2 equivalent of CH4 flux was not influenced by treatments. The CO2 equivalent of N fertilization was greater in MTC, but CO2 equivalent of CH4 flux due to enteric fermentation from sheep was greater in SGO, regardless of cropping sequences. The NGWP was lower in SGO with L-W and W-L than other treatments. Sheep grazing to manage weeds in organic winter wheat-based cropping systems can reduce net GHG emissions compared to minimum tillage with chemical inputs in conventional cropping systems in dryland farming.