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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Soil, Water & Air Resources Research » Research » Publications at this Location » Publication #350377
Research Project: Managing Carbon and Nutrients in Midwestern U.S. Agroecosystems for Enhanced Soil Health and Environmental Quality

Location: Soil, Water & Air Resources Research

Title: An Iowa on-farm carbon and soil health indicator assessment study

Author
item Karlen, Douglas
item OBRYCKI, JOHN - Orise Fellow

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2018
Publication Date: 7/5/2018
Publication URL: https://handle.nal.usda.gov/10113/6545389
Citation: Karlen, D.L., Obrycki, J.F. 2018. An Iowa on-farm carbon and soil health indicator assessment study. Agronomy Journal. https://doi.org/10.2134/agronj2018.02.0113.

Interpretive Summary: Quantifying how soil and crop management practices affect the amount of soil organic carbon (SOC) and other soil health indicators in farm fields is important to understand long-term environmental effects of agricultural practices. This study quantified SOC and other soil health indicator responses to crop rotation and manure/biosolids application rates on a Boone County, Iowa farm. SOC values were similar across all crop rotations and agreed with estimates provided by the Web Soil Survey. When compared to published data for similar Iowa soils, the combined results confirmed that crop rotation had a greater effect on SOC and other soil health indicators than application of manure/biosolids. This information will be useful for conservationists, researchers, and producers.

Technical Abstract: Data from on-farm sites with known long-term management histories are needed to quantify soil biological, chemical, and physical properties influencing carbon stocks and soil health. Surface (0 to 15-cm) and deep core (0 to 122-cm) soil samples were collected from fields under two rotations in Boone County, Iowa. The first was a 5-year corn [Zea mays (L.)], soybean [Glycine max (L.) Merr.], corn, oat [Avena sativa (L.)], and alfalfa [Medicago sativa (L.)] rotation to which 0, 18, or 36 Mg ha-1 of a manure/biosolids mixture was applied prior to planting corn. The second was an 8-year rotation with 6 years of mixed grass and legume pasture followed by corn and an oat crop within which the pasture mixture was reestablished. Soil samples were collected evenly across the predominant soil map units (SMUs). Bulk density (BD), total organic C, water-stable aggregates (WSA), microbial biomass carbon (MBC), pH, Mehlich-3 and DTPA extractable nutrients, electrical conductivity (EC), and nitrogen (total-, NH4-, and NO3-N) were measured. Surface soil carbon data were consistent with Soil Survey values for the various SMUs. Crop rotation effects were more pronounced than manure/biosolid application rate effects. These on-farm data, combined with published data, suggest rotation-based systems may increase soil organic C 1.3 fold (8 ± 4 g kg-1) in central Iowa, USA soils. This study provides on-farm reference values for improving soil health assessment tools such as the Soil Management Assessment Framework (SMAF) and draws attention to the importance of inherent soil properties for these assessments.