• Authors:
    • Dygert, C.
    • Chen, L.
    • Campbell, B.
    • Dick, W.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 69
  • Issue: 6
  • Year: 2014
  • Summary: Soils may be a source or sink of greenhouse gases (carbon dioxide [CO2], nitrous oxide [N2O], and methane [CH4]) that lead to global warming and climate change. While it is known that greenhouse gases are naturally cycled through soil and are part of the carbon (C) and nitrogen (N) cycles, it is not fully understood what effect crop production practices have on this cycling. Therefore, a study was conducted at the longest, continually maintained no-tillage plots in the world at Wooster (50 years no-till), near Wooster, Ohio, and Hoytville (49 years no-till), near Custar, Ohio, that represent two contrasting Ohio soils. Fluxes of greenhouse gases were measured by gas chromatography (GC) biweekly and following rainfall events greater than 1.2 cm (0.5 in) during the growing season of the corn (Zed mays L.), starting in July of 2011 until October of 2011, and then from May of 2012 to July of 2012. Samples were obtained at both sites in plots with rotations of corn after corn (CC) and corn after soybean (Glycine max L.) (CS), and when soils were managed using no-tillage (NT) and chisel or minimum conservation tillage (MT). Comparisons statistically significant at the p <0.10 level are as follows. For CO2 ' the CS rotation yielded lower emissions than the CC at both sites, due to less biomass cycling. For N2 O, the CS rotation yielded lower emissions than the CC at both sites due to less total N fertilizer input in the CS than the CC rotation. The NT system resulted in lower N2 O emissions than the MT system at Hoytville, but not at Wooster. For CH4, soil in the long-term plots often acted as sinks. Global warming potentials were lower for Hoytville than Wooster and lower for rotation of CS than CC at both Hoytville and Wooster. Overall, after about 50 years, it is evident that the use of no-tillage combined with crop rotations can lead to improved environmental (i.e., greenhouse gas emissions and global warming potential) benefits.
  • Authors:
    • DeSutter, D.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 69
  • Issue: 6
  • Year: 2014
  • Authors:
    • Martin, T. A.
    • Morton, L. W.
    • Eigenbrode, S. D.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 69
  • Issue: 6
  • Year: 2014
  • Authors:
    • Harrington, J.,Jr.
    • Howard, I. M.
  • Source: Transactions of the Kansas Academy of Science
  • Volume: 117
  • Issue: 1/2
  • Year: 2014
  • Summary: Nighttime rainfall has long been thought of as an important component to the central Great Plains hydroclimate during the wettest three-month period known as the "late spring-early summer precipitation maximum" from May-July (MJJ), though the climatological characteristics in Kansas are not very well documented in the literature. The nighttime rainfall characteristics are examined based on hourly precipitation data for Topeka, KS and other Kansas stations for a 63-year period from 1950-2012 for May-July. Nighttime rainfall is a major contributor to the overall moisture budget in the Great Plains, contributing over 50% of the overall rainfall total for the three-month period, with an increase in the percentage from May to July. Most nocturnal rainfall events initiate around the local midnight hour, with earlier start times in May compared to June and July. The greatest hourly precipitation tends to occur around the same time, with a gradual step down into the mid-morning hours. Geographically, areas in the eastern portion of the state receive more nighttime rainfall on average for all three months than areas to the west.
  • Authors:
    • Khaliq, M. N.
    • Sushama, L.
    • Il Jeong, D.
  • Source: CLIMATIC CHANGE
  • Volume: 127
  • Issue: 2
  • Year: 2014
  • Summary: The effects of future temperature and hence evapotranspiration increases on drought risk over North America, based on ten current (1970-1999) and ten corresponding future (2040-2069) Regional Climate Model (RCM) simulations from the North American Regional Climate Change Assessment Program, are presented in this study. The ten pairs of simulations considered in this study are based on six RCMs and four driving Atmosphere Ocean Coupled Global Climate Models. The effects of temperature and evapotranspiration on drought risks are assessed by comparing characteristics of drought events identified on the basis of Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspration Index (SPEI). The former index uses only precipitation, while the latter uses the difference (DIF) between precipitation and potential evapotranspiration (PET) as input variables. As short- and long-term droughts impact various sectors differently, multi-scale (ranging from 1- to 12-month) drought events are considered. The projected increase in mean temperature by more than 2 A degrees C in the future period compared to the current period for most parts of North America results in large increases in PET and decreases in DIF for the future period, especially for low latitude regions of North America. These changes result in large increases in future drought risks for most parts of the USA and southern Canada. Though similar results are obtained with SPI, the projected increases in the drought characteristics such as severity and duration and the spatial extent of regions susceptible to drought risks in the future are considerably larger in the case of SPEI-based analysis. Both approaches suggest that long-term and extreme drought events are affected more by the future increases in temperature and PET than short-term and moderate drought events, particularly over the high drought risk regions of North America.
  • Authors:
    • Lal, R.
    • Kadono, A.
    • Nakajima, T.
    • Kumar, S.
    • Fausey, N.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 69
  • Issue: 6
  • Year: 2014
  • Summary: Intensive tillage practices and poorly drained soils of the Midwestern United States are one of the prime reasons for increased greenhouse gas (GHG) fluxes from agriculture. The naturally poorly drained soils prevalent in this region require subsurface drainage for improving aeration and reducing GHG fluxes from soils. However, very little research has been conducted on the combination of tillage and drainage impacts on GHG fluxes from poorly drained soils. Thus, the present study was conducted in central Ohio with specific objective to assess the influences of long-term (18-year) no-tillage (NT) and chisel-till (CT) impacts on carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) fluxes from the soils in plots managed under drained (D) or nondrained (ND) conditions. The experimental site was established on a poorly drained Crosby silt loam soil in 1994 under corn (Zed mays L.)-corn rotation. Measurements of soil CO2, N2 O, and CH4 fluxes were conducted biweekly during 2011 and 2012 using the static chamber technique. In 2011, the annual CO2-C and N2 O-N from NT were 18% and 83%, respectively, lower compared to CT. Similar trends were observed for 2012. Methane fluxes were highly variable in both years.Tillage and drainage influenced seasonal soil GHG emissions; however, differences were not always significant. In general, plots under NT with subsurface drainage produced lower emissions compared to those under CT. Subsurface drainage lowered the emissions compared to those under ND. Results from this study concluded that subsurface drainage in poorly drained soils with long-term NT practice can be beneficial for the environment by emitting lower GHG fluxes compared to tilled soils with no drainage. However, long-term monitoring of these fluxes under diverse cropping systems under poorly drained soils is needed.
  • Authors:
    • Archer, D. W.
    • Lee, J.
  • Source: Scopus
  • Volume: 1
  • Year: 2014
  • Summary: An important driver for the adoption of renewable fuels is reduction in greenhouse gas (GHG) emissions, and the quantity of greenhouse gas reductions achieved is used in determining the fuel feedstocks and conversion pathways that can be used for fuels to meet the U.S. renewable fuels standard. Estimating GHG emissions from cropping system is an important component in quantifying GHG emissions through entire process from feed stock to final product use for oilseed based renewable fuels. Soil Organic Carbon (SOC) change is a key measure for calculating GHG emission from cropping systems because increase of SOC is regarded as C02 deposition from atmosphere to soil. Even though many researchers have simulated long term impacts of cropping system on SOC, the calibration and validation for C dynamic parameters using long-term soil profile data have been limited. The objective of this study is modeling long-term SOC change under impact of Brassica oil seed cropping systems with calibration and validation of soil C dynamics parameters in the EPIC model. We validated crop growth parameters from several areas of Northern Great Plains regions using field scale crop yield and management data at Mandan, ND. Soil C dynamics parameters (microbial decay rate coefficient) were calibrated and validated using soil profile data in 1983, 1991 and 2001 from long-term soil quality studies conducted at Mandan, ND since 1983. After calibration and validation, SOC and crop yields were modeled for each SSURGO soil map unit in Ward County, ND, one of pilot counties being evaluated for potential oilseed supply for hydrotreated renewable jet fuel production. The simulation was conducted under two rotation scenarios, canola-spring wheat-spring wheat and continuous spring wheat with no-tillage. The soil parameters from SSURGO were initialized by 100 year run with continuous spring wheat before imposing the two rotation scenario treatments. The results from 50-year simulation indicate that the canola cropping system is beneficial to store SOC compared to continuous spring wheat in all test map units. However, differences vary across soil map units.
  • Authors:
    • Nafziger, E. D.
    • Lauer, J. G.
    • Herzmann, D.
    • Helmers, M. J.
    • Dick, W. A.
    • Del Grosso, S. J.
    • Abendroth, L. J.
    • Kravchenko, A. N.
    • Anex, R. P., Jr.
    • Necpalova, M.
    • Sawyer, J. E.
    • Scharf, P. C.
    • Strock, J. S.
    • Villamil, M. B.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 69
  • Issue: 6
  • Year: 2014
  • Summary: Variability in soil organic carbon (SOC) results from natural and human processes interacting across time and space, and leads to large variation in the minimum difference in SOC that can be detected with a particular experimental design. Here we report a unique comparison of minimum detectable differences (MDDs) in SOC, and the estimated times required to observe those MDDs across the north central United States, calculated for the two most common SOC experiments: (1) a comparison between two treatments, e.g., moldboard plow (MP) and no-tillage (NT), using a randomized complete block design experiment; and (2) a comparison of changes in SOC over time for a particular treatment, e.g., NT, using a randomized complete block design experiment with time as an additional factor. We estimated the duration of the two experiment types required to achieve MDD through simulation of SOC dynamics. Data for the study came from 13 experimental sites located in Iowa, Illinois, Ohio, Michigan, Wisconsin, Missouri, and Minnesota. Soil organic carbon, bulk density, and texture were measured at four soil depths. Minimum detectable differences were calculated with probability of Type I error of 0.05 and probability of Type II error of 0.15. The MDDs in SOC were highly variable across the region and increased with soil depth. At 0 to 10 cm (0 to 3.9 in) soil depth, MDDs with five replications ranged from 1.04 g C kg(-1) (0.017 oz C lb(-1); 6%) to 7.15 g C kg(-1) (0.114 oz C lb(-1); 31%) for comparison of two treatments; and from 0.46 g C kg(-1) (0.007 oz C lb(-1); 3%) to 3.12 g C kg(-1) (0.050 oz C lb(-1); 13%) for SOC change over time. Large differences were also predicted in the experiment duration required to detect a difference in SOC between MP and NT (from 8 to > 100 years with five replications), or a change in SOC over time under NT management (from 11 to 71 years with five replications). At most locations, the time required to detect a change in SOC under NT was shorter than the time required to detect a difference between MP and NT. Minimum detectable difference and experiment duration decreased with the number of replications and were correlated with SOC variability and soil texture of the experimental sites, i.e., they tended to be lower in fine textured soils. Experiment duration was also reduced by increased crop productivity and the amount of residue left on the soil. The relationships and methods described here enable the design of experiments with high power of detecting differences and changes in SOC and enhance our understanding of how management practices influence SOC storage.
  • Authors:
    • Posner, J. L.
    • Hedtcke, J. L.
    • Kucharik, C. J.
    • Osterholz, W. R.
  • Source: JOURNAL OF ENVIRONMENTAL QUALITY
  • Volume: 43
  • Issue: 6
  • Year: 2014
  • Summary: Agriculture in the midwestern United States is a major anthropogenic source of nitrous oxide (N2O) and is both a source and sink for methane (CH4), but the degree to which cropping systems differ in emissions of these gases is not well understood. Our objectives were to determine if fluxes of N2O and CH4 varied among cropping systems and among crop phases within a cropping system. We compare N2O and CH4 fluxes over the 2010 and 2011 growing seasons from the six cropping systems at the Wisconsin Integrated Cropping Systems Trial (WICST), a 20-yr-old cropping systems experiment. The study is composed of three grain and three forage cropping systems spanning a spectrum of crop diversity and perenniality that model a wide range of realistic cropping systems that differ in management, crop rotation, and fertilizer regimes. Among the grain systems, cumulative growing season N2O emissions were greater for continuous corn (Zea mays L.) (3.7 kg N2O-N ha(-1)) than corn-soybean [Glycine max (L.) Merr.] (2.0 kg N2O-N ha(-1)) or organic corn-soybean-wheat (Triticum aestivum L.) (1.7 kg N2O-N ha(-1)). Among the forage systems, cumulative growing-season N2O emissions were greater for organic corn-alfalfa (Medicago sativa L.)-alfalfa (2.9 kg N2O-N ha(-1)) and conventional corn-alfalfa-alfalfa-alfalfa (2.5 kg N2O-N ha(-1)), and lower for rotational pasture (1.9 kg N2O-N ha(-1)). Application of mineral or organic N fertilizer was associated with elevated N2O emissions. Yield-scaled emissions (kg N2O-N Mg-1) did not differ by cropping system. Methane fluxes were highly variable and no effect of cropping system was observed. These results suggest that extended and diversified cropping systems could reduce area-scaled N2O emissions from agriculture, but none of the systems studied significantly reduced yield-scaled N2O emissions.
  • Authors:
    • Srinivasan, R.
    • Kling, C. L.
    • Jha, M. K.
    • Campbell, T. D.
    • Herzmann, D. E.
    • Arritt, R. W.
    • Gassman, P. W.
    • Panagopoulos, Y.
    • White, M.
    • Arnold, J. G.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 69
  • Issue: 6
  • Year: 2014
  • Summary: Agricultural nonpoint source pollution is the main source of nitrogen (N) and phosphorus (P) in the intensely row-cropped Upper Mississippi River Basin (UMRB) stream system and is considered the primary cause of the northern Gulf of Mexico hypoxic zone according to the US Environmental Protection Agency. A point of crucial importance in this region is therefore how intensive corn (Zea mays L.)-based cropping systems for food and fuel production can be sustainable and coexist with a healthy water environment, not only under existing climate conditions but also under a changed climate in the future. To address this issue, a UMRB integrated modeling system has been built with a greatly refined 12-digit subbasin structure based on the Soil and Water Assessment Tool (SWAT) water quality model, which is capable of estimating landscape and in-stream water and pollutant yields in response to a wide array of alternative cropping and/or management strategies and climatic conditions. The effects of the following four agricultural management scenarios on crop production and pollutant loads exported from the cropland of the UMRB to streams and rivers were evaluated: (1) expansion of continuous corn across the entire basin, (2) adoption of no-till on all corn and soybean (Glycine max L.) fields in the region, (3) substitution of the traditional continuous corn and corn-soybean rotations with an extended five-year rotation consisting of corn, soybean, and three years of alfalfa (Medicago sativa L.), and (4) implementation of a winter cover crop within the baseline rotations. The effects of each management scenario were evaluated both for current climate and a projected midcentury (2046 to 2065) climate from a General Circulation Model (GCM). All four scenarios behaved similarly under the historical and future climate, generally resulting in reduced erosion and nutrient loadings to surface water bodies compared to the baseline agricultural management. Continuous corn was the only scenario which resulted in increased N pollution while no-till was the most environmentally effective and able to sustain production at almost the same levels. Rye (Secale cereale L.) cover crop within the fallow period was also effective in reducing erosion and both sediment-bound and soluble forms of nutrients. The results indicated that alternative management practices could reduce sediment, N, and P exports from UMRB cropland by up to 50% without significantly affecting yields. Results for the climate change scenario showed that the effectiveness of the management scenarios was strongly linked to the reduced water availability predicted under the future climate, which assisted in mitigating pollutant transport, although with a small loss of production.