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ARS Home » Plains Area » Brookings, South Dakota » Integrated Cropping Systems Research » Research » Publications at this Location » Publication #133874
Title: SOIL CARBON AND GLOMALIN CONCENTRATION UNDER CROP AND TILLAGE MANAGEMENT IN EASTERN SOUTH DAKOTA

Author
item Pikul Jr, Joseph
item Wright, Sara
item Jawson, Linda
item Ellsbury, Michael

Submitted to: International Humic Substances Society Conference
Publication Type: Proceedings
Publication Acceptance Date: 4/19/2002
Publication Date: 6/28/2002
Citation: Pikul Jr, J.L., Wright, S.E., Jawson, L., Ellsbury, M.M. 2002. Soil carbon and glomalin concentration under crop and tillage management in eastern south dakota. International Humic Substances Society Conference.

Interpretive Summary: Increased loss of soil organic matter (SOM) has been associated with increased tillage intensity and rate of loss can be a function of soil type, climate, and cropping practice. Crop rotation, residue management, fertility management, and tillage management have an impact on sustainability of the soil resource. Humic substances, a portion of SOM, are derived from biological and chemical transformations of organic materials. Composition of humic substances varies according to types of plant material and microbial populations and are important to soil management because they are linked to erosion reduction and soil tilth. Glomalin, an ubiquitous, abundant glycoprotein originating from hyphae of arbuscular mycorrhizal fungi, is a major and unique component of SOM. Glomalin concentration is correlated with aggregate stability and is thought to be a relatively sensitive indicator of change in soil condition. We found a higher concentration of glomalin, and total soil carbon in aggregates that resisted disintegration and these aggregates were from the no tillage farm. Results show a link between no tillage and improved soil quality. Further, we found significant differences in properties among aggregate classes suggesting that organic cementing agents (humic materials or glomalin) are not uniformly distributed across all aggregate groups.

Technical Abstract: Loss of soil organic matter (SOM) has been associated with increased tillage. Glomalin, a component of SOM, originates from hyphae of arbuscular mycorrhizal fungi and is thought to be important in maintaining soil structure. Objectives were to determine effect of tillage on soil carbon (C) and glomalin concentration. About 10 kg of soil from the top 50 mm was randomly collected from no tillage (NT) and conventional tillage (CT) farms. Samples were dried and a rotary sieve was used to separate samples into aggregate groups. Group 1 was soil <0.42 mm, group 2 was 0.42-0.84 mm, group 3 was 0.84-2.0 mm, group 4 was 2.0-6.4 mm, and group 5 was 6.4-12.7 mm. Soil C was measured by combustion and total glomalin immunoreactive (TGIR), an indicator of more recently deposited glomalin, was measured with an enzyme-linked immunosorbent assay on all aggregate groups. Results from dry sieving show that soil aggregates from the NT farm resisted breakdown when compared with aggregates from the CT farm. There was a significant difference in total C between NT and CT within aggregate groups 4 and 5. Concentration of glomalin and total C was higher in aggregates that resisted disintegration and these aggregates were from the NT farm. Results show a link between NT and improved soil quality. Differences in properties among aggregate classes suggest that organic cementing agents (humic materials or glomalin) are not uniformly distributed across all aggregate groups.