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Douglas L. Karlen
D.L. Karlen Consulting LLC, St. Paul, MN 55102, USA

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Journal article
Published: 15 April 2021 in Sustainability
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Corn (Zea mays L.) stover is used as a biofuel feedstock in the U.S. Selection of stover harvest rates for soils is problematic, however, because excessive stover removal may have consequences on plant available P and K concentrations. Our objective was to quantify stover harvest impacts on topsoil P and K contents in the southeastern U.S. Coastal Plain Ultisols. Five stover harvest rates (0, 25, 50, 75 and 100% by wt) were removed for five years from replicated plots. Grain and stover mass with P and K concentration data were used to calculate nutrient removal. Mehlich 1 (M1)-extractable P and K concentrations were used to monitor changes within the soils. Grain alone removed 13–15 kg ha−1 P and 15–18 kg ha−1 K each year, resulting in a cumulative removal of 70 and 85 kg ha−1 or 77 and 37% of the P and K fertilizer application, respectively. Harvesting stover increased nutrient removal such that when combined with grain removed, a cumulative total of 95% of the applied P and 126% of fertilizer K were taken away. This caused M1 P and K levels to decline significantly in the first year and even with annual fertilization to remain relatively static thereafter. For these Ultisols, we conclude that P and K fertilizer recommendations should be fine-tuned for P and K removed with grain and stover harvesting and that stover harvest of >50% by weight will significantly decrease soil test M1 P and K contents.

ACS Style

Jeffrey Novak; James Frederick; Don Watts; Thomas Ducey; Douglas Karlen. Corn Stover Removal Responses on Soil Test P and K Levels in Coastal Plain Ultisols. Sustainability 2021, 13, 4401 .

AMA Style

Jeffrey Novak, James Frederick, Don Watts, Thomas Ducey, Douglas Karlen. Corn Stover Removal Responses on Soil Test P and K Levels in Coastal Plain Ultisols. Sustainability. 2021; 13 (8):4401.

Chicago/Turabian Style

Jeffrey Novak; James Frederick; Don Watts; Thomas Ducey; Douglas Karlen. 2021. "Corn Stover Removal Responses on Soil Test P and K Levels in Coastal Plain Ultisols." Sustainability 13, no. 8: 4401.

Journal article
Published: 28 September 2020 in Environmental and Sustainability Indicators
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The Soil Management Assessment Framework (SMAF) was developed to collectively assess biological, chemical, and physical soil health changes due to management practices. SMAF scoring curves were designed to be site-specific but were never validated at national scale. Our goal was to verify the national effectiveness of SMAF for detecting changes induced by conservation practices. Data from 456 articles representing the U.S. was compiled as input for a SMAF analysis. Soil organic-C (SOC), microbial biomass-C (MBC), β-glucosidase activity (BG), macroaggregate stability (AS), bulk density (BD), pH, soil-test P and K indices and an overall soil quality index (SQI) were computed. Measured, scored, and SQI values were used to evaluate tillage intensity [conventional (CT), reduced tillage (RT), no-till (NT), and zero disturbance (perennial systems; PER)] and soil cover [annual cropping systems without cover crops (ANCC), annual cropping systems with cover crops (ACC), and year-round soil cover (perennial systems; PER)]. Reducing tillage intensity and increasing soil cover increased topsoil SOC, MBC, BG, and AS values (measured and scored). SMAF scoring curves were sensitive to agronomic practice effects on soil function. The highest SQI values were associated with perennial systems (zero soil disturbance) and year-round living roots. Within annual cropping systems, cover cropping, and NT demonstrated better soil biological and physical functioning. However, SMAF scores underestimated the effects for SOC and BG and overestimated the effects for AS, suggesting the algorithms for those indicators should be reevaluated and improved. Overall, this national assessment confirmed the utility of SMAF and highlighted benefits of conservation practices.

ACS Style

Márcio R. Nunes; Douglas L. Karlen; Kristen S. Veum; Thomas B. Moorman. A SMAF assessment of U.S. tillage and crop management strategies. Environmental and Sustainability Indicators 2020, 8, 100072 .

AMA Style

Márcio R. Nunes, Douglas L. Karlen, Kristen S. Veum, Thomas B. Moorman. A SMAF assessment of U.S. tillage and crop management strategies. Environmental and Sustainability Indicators. 2020; 8 ():100072.

Chicago/Turabian Style

Márcio R. Nunes; Douglas L. Karlen; Kristen S. Veum; Thomas B. Moorman. 2020. "A SMAF assessment of U.S. tillage and crop management strategies." Environmental and Sustainability Indicators 8, no. : 100072.

Journal article
Published: 15 July 2020 in Sustainability
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Soil organic carbon (SOC) influences several soil functions, making it one of the most important soil health indicators. Its quantity is determined by anthropogenic and inherent factors that must be understood to improve SOC management and interpretation. Topsoil (≤15 cm) SOC response to tillage depth and intensity, cover crops, stover removal, manure addition, and various cropping systems was assessed using 7610 observations from eight U.S. regions. Overall, including cover crops, reducing tillage depth and intensity increased SOC. The positive effects of cover crops were more noticeable in South Central, Northwest, and Midwest regions. Removing high rates (>65%) of crop residue decreased SOC in Midwestern and Southeastern soils. Depending on region, applying manure increased SOC by 21 to 41%, compared to non-manured soils. Diversified cropping systems (e.g., those utilizing small mixed vegetables, perennials, or dairy-based systems) had the highest topsoil SOC content, while more intensive annual row crops and large-scale single vegetable production systems, had the lowest. Among inherent factors, SOC increased as precipitation increased, but decreased as mean annual temperature increased. Texture influenced SOC, showing higher values in fine-texture than coarse-texture soils. Finally, this assessment confirmed that SOC can be a sensitive soil health indicator for evaluating conservation practices.

ACS Style

Márcio Nunes; Harold Van Es; Kristen Veum; Joseph Amsili; Douglas Karlen. Anthropogenic and Inherent Effects on Soil Organic Carbon across the U.S. Sustainability 2020, 12, 5695 .

AMA Style

Márcio Nunes, Harold Van Es, Kristen Veum, Joseph Amsili, Douglas Karlen. Anthropogenic and Inherent Effects on Soil Organic Carbon across the U.S. Sustainability. 2020; 12 (14):5695.

Chicago/Turabian Style

Márcio Nunes; Harold Van Es; Kristen Veum; Joseph Amsili; Douglas Karlen. 2020. "Anthropogenic and Inherent Effects on Soil Organic Carbon across the U.S." Sustainability 12, no. 14: 5695.

Journal article
Published: 08 March 2020 in Sustainability
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Tillage intensity affects soil structure in many ways but the magnitude and type (+/−) of change depends on site-specific (e.g., soil type) and experimental details (crop rotation, study length, sampling depth, etc.). This meta-analysis examines published effects of chisel plowing (CP), no-tillage (NT) and perennial cropping systems (PER) relative to moldboard plowing (MP) on three soil structure indicators: wet aggregate stability (AS), bulk density (BD) and soil penetration resistance (PR). The data represents four depth increments (from 0 to >40-cm) in 295 studies from throughout the continental U.S. Overall, converting from MP to CP did not affect those soil structure indicators but reducing tillage intensity from MP to NT increased AS in the surface (40-cm). Among those three soil structure indicators, AS was the most sensitive to management practices; thus, it should be used as a physical indicator for overall soil health assessment. In addition, based on this national meta-analysis, we conclude that reducing tillage intensity improves soil structure, thus offering producers assurance those practices are feasible for crop production and that they will also help sustain soil resources.

ACS Style

Márcio R. Nunes; Douglas L. Karlen; Thomas B. Moorman. Tillage Intensity Effects on Soil Structure Indicators—A US Meta-Analysis. Sustainability 2020, 12, 2071 .

AMA Style

Márcio R. Nunes, Douglas L. Karlen, Thomas B. Moorman. Tillage Intensity Effects on Soil Structure Indicators—A US Meta-Analysis. Sustainability. 2020; 12 (5):2071.

Chicago/Turabian Style

Márcio R. Nunes; Douglas L. Karlen; Thomas B. Moorman. 2020. "Tillage Intensity Effects on Soil Structure Indicators—A US Meta-Analysis." Sustainability 12, no. 5: 2071.

Journal article
Published: 15 August 2019 in Agronomy
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The Midwestern U.S. landscape is one of the most highly altered and intensively managed ecosystems in the country. The predominant crops grown are maize (Zea mays L.) and soybean [Glycine max (L.) Merr]. They are typically grown as monocrops in a simple yearly rotation or with multiple years of maize (2 to 3) followed by a single year of soybean. This system is highly productive because the crops and management systems have been well adapted to the regional growing conditions through substantial public and private investment. Furthermore, markets and supporting infrastructure are highly developed for both crops. As maize and soybean production have intensified, a number of concerns have arisen due to the unintended environmental impacts on the ecosystem. Many areas across the Midwest are experiencing negative impacts on water quality, soil degradation, and increased flood risk due to changes in regional hydrology. The water quality impacts extend even further downstream. We propose the development of an innovative system for growing maize and soybean with perennial groundcover to recover ecosystem services historically provided naturally by predominantly perennial native plant communities. Reincorporating perennial plants into annual cropping systems has the potential of restoring ecosystem services without negatively impacting grain crop production and offers the prospect of increasing grain crop productivity through improving the biological functioning of the system.

ACS Style

Kenneth J. Moore; Robert P. Anex; Amani E. Elobeid; Shuizhang Fei; Cornelia B. Flora; A. Susana Goggi; Keri L. Jacobs; Prashant Jha; Amy L. Kaleita; Douglas L. Karlen; David A. Laird; Andrew W. Lenssen; Thomas Lübberstedt; Marshall D. McDaniel; D. Raj Raman; Sharon L. Weyers. Regenerating Agricultural Landscapes with Perennial Groundcover for Intensive Crop Production. Agronomy 2019, 9, 458 .

AMA Style

Kenneth J. Moore, Robert P. Anex, Amani E. Elobeid, Shuizhang Fei, Cornelia B. Flora, A. Susana Goggi, Keri L. Jacobs, Prashant Jha, Amy L. Kaleita, Douglas L. Karlen, David A. Laird, Andrew W. Lenssen, Thomas Lübberstedt, Marshall D. McDaniel, D. Raj Raman, Sharon L. Weyers. Regenerating Agricultural Landscapes with Perennial Groundcover for Intensive Crop Production. Agronomy. 2019; 9 (8):458.

Chicago/Turabian Style

Kenneth J. Moore; Robert P. Anex; Amani E. Elobeid; Shuizhang Fei; Cornelia B. Flora; A. Susana Goggi; Keri L. Jacobs; Prashant Jha; Amy L. Kaleita; Douglas L. Karlen; David A. Laird; Andrew W. Lenssen; Thomas Lübberstedt; Marshall D. McDaniel; D. Raj Raman; Sharon L. Weyers. 2019. "Regenerating Agricultural Landscapes with Perennial Groundcover for Intensive Crop Production." Agronomy 9, no. 8: 458.

Journal article
Published: 22 December 2018 in Journal of Geophysical Research: Biogeosciences
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Soil redistribution (erosion and deposition) can greatly affect the fate of soil organic carbon (SOC) in agroecosystems. Landscape topography is one of the key factors controlling erosion processes and creating spatial variability in SOC. We combined carbon (C) isoscape (isotopic landscape) analysis, historic orthophoto interpretation, cesium (137Cs) inventory measurement, and digital terrain analysis to quantify SOC dynamics and soil redistribution relationship and their responses to landscape topography in an Iowa cropland field with soybean/maize (C3/C4) rotation. The historic orthophotos and 137Cs were used to reflect soil redistribution before and after the 1960s, respectively. Topography‐based models were developed to simulate 137Cs inventory, SOC density, and C isotopes using stepwise principal component regression (SPCR). Spatial patterns of SOC were similar to soil erosion/deposition patterns with high SOC density in depositional areas and low SOC density in eroded areas. Soil redistribution, SOC density, and isotopic signature of SOC (δ13C) were highly correlated with topographic metrics, suggesting that topographic heterogeneity drove the spatial variability in erosion and SOC dynamics. Considering the isotopic composition of SOC, C3‐derived SOC density was strongly controlled by topographic metrics, but C4‐derived SOC density showed weaker expression of spatial pattern and poor correlation to topographic parameters. The resulting topography‐based SPCR models captured more than 60% of the variability in SOC density, δ13C, and C3‐derived SOC density, but could not reliably predict C4‐derived SOC density. Our results indicate that exploring C isotopes in response to soil erosion is important to understand the fate of eroded SOC within croplands under C3/C4 cultivation.

ACS Style

Xia Li; Gregory W. McCarty; Douglas L. Karlen; Cynthia A. Cambardella; William Effland. Soil Organic Carbon and Isotope Composition Response to Topography and Erosion in Iowa. Journal of Geophysical Research: Biogeosciences 2018, 123, 3649 -3667.

AMA Style

Xia Li, Gregory W. McCarty, Douglas L. Karlen, Cynthia A. Cambardella, William Effland. Soil Organic Carbon and Isotope Composition Response to Topography and Erosion in Iowa. Journal of Geophysical Research: Biogeosciences. 2018; 123 (12):3649-3667.

Chicago/Turabian Style

Xia Li; Gregory W. McCarty; Douglas L. Karlen; Cynthia A. Cambardella; William Effland. 2018. "Soil Organic Carbon and Isotope Composition Response to Topography and Erosion in Iowa." Journal of Geophysical Research: Biogeosciences 123, no. 12: 3649-3667.