Long-term cropping system effects on carbon sequestration in eastern Oregon.

Full Abstract

Soil organic carbon (SOC) has beneficial effects on soil quality and productivity. Cropping systems that maintain and/or improve levels of SOC may lead to sustainable crop production. This study evaluated the effects of long-term cropping systems on C sequestration. Soil samples were taken at 0- to 10-, 10- to 20-, 20- to 30-, and 30- to 40-cm soil depth profiles from grass pasture (GP), conventional tillage (CT) winter wheat (Triticum aestivum L.)-fallow (CTWF), and fertilized and unfertilized plots of continuous winter wheat (WW), spring wheat (SW), and spring barley (Hordeum vulgare L.) (SB) monocultures under CT and no-till (NT). The samples were analyzed for soil organic matter (SOM) and SOC was derived. Ages of experiments ranged from 6 to 73 yr. Compared to 1931 SOC levels (initial year), CTWF reduced SOC by 9 to 12 Mg ha(-1) in the 0- to 30-cm zone. Grass pasture increased SOC by 6 Mg ha(-1) in the 0- to 10-cm zone but decreased SOC by 3 Mg ha(-1) in the 20- to 30-cm zone. Continuous CT monocultures depleted SOC in the top 0- to 10-cm zone and the bottom 20- to 40-cm zone but maintained SOC levels close to 1931 SOC levels in the 10- to 20-cm layer. Continuous NT monocultures accumulated more SOC in the 0- to 10-cm zone than in deeper zones. Total SOC (0- to 40-cm zone) was highest under GP and continuous cropping and lowest under CTWF. Fertilizer increased total SOC only under CTWW and CTSB by 13 and 7 Mg ha(-1) in 13 yr, respectively. Practicing NT for only 6 yr had started to reverse the effect of 73 yr of CTWF. Compared to CTWF, NTWW and NTSW sequestered C at rates of 2.6 and 1.7 Mg ha(-1) yr(-1), respectively, in the 0- to 40-cm zone. This study showed that the potential to sequester C can be enhanced by increasing cropping frequency and eliminating tillage.

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Author information

Author/s: Machado, Stephen (S); Rhinhart, Karl (K); Petrie, Steve (S);

Affiliation: Oregon State University, Columbia Basin Agricultural Research Center, Pendleton, OR 97801, USA. Stephan.Machado(-atsign-)oregonstate.edu

Journal and publication information

Publication Type: Comparative Study; Journal Article

Journal: Journal of environmental quality (J Environ Qual), published in United States. (Language: eng)

Reference: -2006 Jul-Aug; vol 35 (issue 4) : pp 1548-53

Dates: Created 2006/07/07; Completed 2006/12/05;

PMID: 16825475, status: MEDLINE (last retrieval date: 12/26/2008)

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Agriculture - methods
Biomass
Carbon - analysis; metabolism
Conservation of Natural Resources
Crops, Agricultural - growth & development
Environmental Monitoring

Environmental Monitoring
Fertilizers
Geography
Oregon
Organic Chemicals - chemistry; metabolism
Soil

Associated Chemicals: Fertilizers (0) ; Organic Chemicals (0) ; Soil (0) ; Carbon (7440-44-0)

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