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ARS Home » Pacific West Area » Pendleton, Oregon » Columbia Plateau Conservation Research Center » Research » Publications at this Location » Publication #344203
Title: Change in soil organic carbon after five years of continuous winter wheat or switchgrass

Author
item CHATTERJEE, A - North Dakota State University
item Long, Daniel
item PIERCE, F - Washington State University

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2018
Publication Date: 3/22/2018
Publication URL: https://handle.nal.usda.gov/10113/6472322
Citation: Chatterjee, A., Long, D.S., Pierce, F. 2018. Change in soil organic carbon after five years of continuous winter wheat or switchgrass. Soil Science Society of America Journal. 82(2):332-342. doi:10.2136/sssaj2017.08.0290.
DOI: https://doi.org/10.2136/sssaj2017.08.0290

Interpretive Summary: Switchgrass has been considered for cultivation as a biomass crop in the U.S. midwest where there is plenty of moisture. This study investigated the effect of perennial grass grown for biofuel on the amount of carbon sequestered in soils that traditionally were used to support winter wheat in a semi-arid environment. The study grew switchgrass and annual winter wheat in small plots for five years, and considered water supply and carbon down to 48 inches in the soil. These crops were grown under about 17 inches of annual rainfall found under dryland conditions near Pendleton, Oregon. Sprinkler irrigation was used to augment this "low" regime and create "medium" and "high" precipitation regimes. After five years of cropping, winter wheat produced more biomass carbon than switchgrass but switchgrass contributed more carbon to the soil than wheat. The increase in carbon was limited to the first foot of soil with no significant change below this depth. Soil organic carbon in dry cropland is resistant to a shift in crop species. Switchgrass does not increase SOC more than winter wheat in dry cropland of the semi-arid Pacific Northwest.

Technical Abstract: Perennial grasses have been promoted to supply cellulose for ethanol production but possible consequences on soil organic carbon (SOC) should be assessed before adoption in a given region. Specific objectives were to (i) compare above-ground biomass C production and depth distribution of SOC content of winter wheat (Triticum aestivum L.) and switchgrass (Panicum virgatum L.), (ii) determine the contribution of switchgrass to SOC, and (iii) characterize soil C inventories under each crop across a wide range of precipitation regimes. A 6-yr (2008-13) field study with winter wheat and switchgrass cv. Blackwell was conducted near Adams, OR, U.S. Solid set sprinkler irrigation was used to create a productivity gradient of low, intermediate, and high precipitation levels. The contribution of switchgrass to SOC was identified with d13C measurements. Winter wheat had significantly higher 5-yr-average aboveground biomass C production than switchgrass across precipitation levels and winter wheat under high precipitation produced significantly higher aboveground biomass C than medium and low precipitation. After 6-yr, SOC did not change under switchgrass at any depth increment. Results of d13C indicated switchgrass contributed profile SOC of 5.99, 5.41, and 9.47 Mg C ha-1 at low, intermediate, and high precipitation levels. Soil organic carbon in dry cropland is resistant to a shift in crop species. Switchgrass does not increase SOC more than winter wheat in dry cropland of the semi-arid Pacific Northwest.