Thomas Sauer

Dr. Thomas Sauer


Research Focus & Metrics

Academic Career Length

17Years (2010-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
2 May 2012 in Plant and Soil
Verified
Journal Article
Closed access
PDF file
TSThomas Sauer
Thomas Sauer
DJDavid E. James
David E. James
CCCynthia A. Cambardella
Cynthia A. Cambardella
GRGuillermo Hernandez Ramirez
Guillermo Hernandez Ramirez

8 January 2015 in Sustainability
Verified
Journal Article
Open access
PDF file
YCYury Chendev
Yury Chendev
TSThomas Sauer
Thomas Sauer
GRGuillermo Hernandez Ramirez
Guillermo Hernandez Ramirez
CBC. Lee Burras
C. Lee Burras
The physiographic region of the Central Russian Upland, situated in the Central part of Eastern Europe, is characterized by very fertile grassland soils—Chernozems (Mollisols in the USDA taxonomy). However, over the last several centuries this region has experienced intense land-use conversion. The most widespread and significant land-use change is the extensive cultivation of these soils. As a result, Chernozems of the region that were some of the most naturally fertile soils in the world with thick A horizons had become, by the second half of the 19th century, weakly productive, with decreased stocks of organic matter. When not protected by plant cover, water and wind erosion degraded the open fields. The investigation of methods for rehabilitation and restoration of Chernozems resulted in the practice of afforestation of agricultural lands (mainly by windbreak planting). Preferences of agroforestry practices were initially connected with protection of cropland from wind and water erosion, improvement of microclimate for crop growth, and providing new refugia for wild animal and plant habitats. During the last several decades, tree windbreaks have begun to be viewed as ecosystems with great potential for atmospheric carbon sequestration, which plays a positive role in climate change mitigation. For the evaluation of windbreak influence on Chernozem soils, a study was developed with three field study areas across a climatic gradient from cool and wet in the north of the region to warm and dry in the south. Windbreak age ranged from 55–57 years. At each site, soil pits were prepared within the windbreak, the adjacent crop fields of 150 years of cultivation, and nearby undisturbed grassland. Profile descriptions were completed to a depth of 1.5 m. A linear relationship was detected between the difference in organic-rich surface layer (A + AB horizon) thickness of soils beneath windbreaks and undisturbed grasslands and a climate index, the hydrothermal coefficient (HTC). These results indicate that windbreaks under relatively cooler and wetter climate conditions are more favorable for organic matter accumulation in the surface soil. For the 0–100 cm layer of the Chernozems beneath windbreaks, an increase in organic C stocks comparable with undisturbed grassland soils (15–63 Mg·ha−1) was detected. Significant growth of soil organic matter stocks was identified not only for the upper 30 cm, but also for the deeper layer (30–100 cm) of afforested Chernozems. These findings illustrate that, in the central part of Eastern Europe, tree windbreaks improve soil quality by enhancing soil organic matter while providing a sink for atmospheric carbon in tree biomass and soil organic matter.

23 December 2014 in Nutrient Cycling in Agroecosystems
Verified
Journal Article
Closed access
PDF file
TSThomas Sauer
Thomas Sauer
WCWayne K. Coblentz
Wayne K. Coblentz
ATAndrew L. Thomas
Andrew L. Thomas
KBKris R. Brye
Kris R. Brye
DBDavid K. Brauer
David K. Brauer
KHKevin A. Hickie
Kevin A. Hickie

3 March 2014
Verified
Book Chapter
Closed access
PDF file
YCYury G. Chendev
Yury G. Chendev
LNLarisa L. Novykh
Larisa L. Novykh
TSThomas Sauer
Thomas Sauer
APAleksandr N. Petin
Aleksandr N. Petin
EZEvgeny A. Zazdravnykh
Evgeny A. Zazdravnykh
CBC. Lee Burras
C. Lee Burras

17 July 2019 in Remote Sensing
Verified
Journal Article
Open access
PDF file
CDChristian Dold
Christian Dold
JHJerry Hatfield
Jerry Hatfield
JPJohn H. Prueger
John H. Prueger
TMThomas B Moorman
Thomas B Moorman
TSThomas Sauer
Thomas Sauer
KWKenneth Wacha
Kenneth Wacha
The Midwestern US is dominated by corn (Zea mays L.) and soybean (Glycine max [L.] Merr.) production, and the carbon dynamics of this region are dominated by these production systems. An accurate regional estimate of gross primary production (GPP) is imperative and requires upscaling approaches. The aim of this study was to upscale corn and soybean GPP (referred to as GPPcalc) in four counties in Central Iowa in the 2016 growing season (DOY 145–269). Eight eddy-covariance (EC) stations recorded carbon dioxide fluxes of corn (n = 4) and soybean (n = 4), and net ecosystem production (NEP) was partitioned into GPP and ecosystem respiration (RE). Additional field-measured NDVI was used to calculate radiation use efficiency (RUEmax). GPPcalc was calculated using 16 MODIS satellite images, ground-based RUEmax and meteorological data, and improved land use maps. Seasonal NEP, GPP, and RE ( x ¯ ± SE) were 678 ± 63, 1483 ± 100, and −805 ± 40 g C m−2 for corn, and 263 ± 40, 811 ± 53, and −548 ± 14 g C m−2 for soybean, respectively. Field-measured NDVI aligned well with MODIS fPAR (R2 = 0.99), and the calculated RUEmax was 3.24 and 1.90 g C MJ−1 for corn and soybean, respectively. The GPPcalc vs. EC-derived GPP had a RMSE of 2.24 and 2.81 g C m−2 d−1, for corn and soybean, respectively, which is an improvement to the GPPMODIS product (2.44 and 3.30 g C m−2 d−1, respectively). Corn yield, calculated from GPPcalc (12.82 ± 0.65 Mg ha−1), corresponded well to official yield data (13.09 ± 0.09 Mg ha−1), while soybean yield was overestimated (6.73 ± 0.27 vs. 4.03 ± 0.04 Mg ha−1). The approach presented has the potential to increase the accuracy of regional corn and soybean GPP and grain yield estimates by integrating field-based flux estimates with remote sensing reflectance observations and high-resolution land use maps.

23 March 2019 in Agronomy
Verified
Journal Article
Open access
PDF file
CDChristian Dold
Christian Dold
JHJoshua Heitman
Joshua Heitman
GGGill Giese
Gill Giese
AHAdam Howard
Adam Howard
john havlinjohn havlin
john havlin
TSThomas Sauer
Thomas Sauer
Water stress can positively or negatively impact grape yield and yield quality, and there is a need for wine growers to accurately regulate water use. In a four-year study (2010–2013), energy balance fluxes were measured with an eddy-covariance (EC) system in a North Carolina vineyard (Vitis vinifera cv. Chardonnay), and evapotranspiration (ET) and the Crop Water Stress Index (CWSI) calculated. A multiple linear regression model was developed to upscale ET using air temperature (Ta), vapor pressure deficit (VPD), and Landsat-derived Land Surface Temperature (LST) and Enhanced Vegetation Index (EVI). Daily ET reached values of up to 7.7 mm day−1, and the annual ET was 752 ± 59 mm, as measured with the EC system. The grapevine CWSI was between 0.53–0.85, which indicated moderate water stress levels. Median vineyard EVI was between 0.22 and 0.72, and the EVI range (max–min) within the vineyard was 0.18. The empirical models explained 75%–84% of the variation in ET, and all parameters had a positive linear relationship to ET. The Root Mean Square Error (RMSE) was 0.52–0.62 mm. This study presents easily applicable approaches to analyzing water dynamics and ET. This may help wine growers to cost-effectively quantify water use in vineyards.