• Authors:
    • Zhang, Y.
    • McNulty, S.
    • Sun, G.
    • Segura, C.
  • Source: Journal of Soil and Water Conservation
  • Volume: 69
  • Issue: 2
  • Year: 2014
  • Summary: Rainfall runoff erosivity (R) is one key climate factor that controls water erosion. Quantifying the effects of climate change-induced erosivity change is important for identifying critical regions prone to soil erosion under a changing environment. In this study we first evaluate the changes of R from 1970 to 2090 across the United States under nine climate conditions predicted by three general circulation models for three emissions scenarios (A2, A1B, and B1) from the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Then, we identify watersheds that are most vulnerable to future climate change in terms of soil erosion potential. We develop a novel approach to evaluate future trends of R magnitude and variance by incorporating both the rate of change with time as well as the level of agreement between climatic projections. Our results show that mean decadal R values would increase with time according to all nine climatic projections considered between 1970 and 2090. However, these trends vary widely spatially. In general, catchments in the northeastern and northwestern United States are characterized by strong increasing trends in R, while the trends in the midwestern and southwestern United States are either weak or inconsistent among the nine climatic projections considered. The northeastern and northwestern United States will likely experience a significant increase in annual variability of R (i.e., increase in extreme events). Conversely the variability of R is unlikely to change in large areas of the Midwest. At the watershed scale (8-digit Hydrologic Unit Code), the mean vulnerability to erosion scores vary between -0.12 and 0.35 with a mean of 0.04. The five hydrologic regions with the highest mean vulnerability to erosion are 5, 6, 2, 1, and 17, with values varying between 0.06 and 0.09. These regions occupy large areas of Ohio, Maryland, Indiana, Vermont, and Illinois, with mean erosion vulnerability score statewide above 0.08. Future watershed management aiming at reducing soil erosion should focus on areas with the highest soil erosion vulnerability identified by this study.
  • Authors:
    • Sperow, M.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 193
  • Year: 2014
  • Summary: The Intergovernmental Panel on Climate Change (IPCC) provides a method to estimate soil organic carbon (SOC) stock changes relative to the SOC stock under native vegetation. This manuscript modifies the IPCC approach to use the ending SOC stock from the previous inventory as the SOC stock that is changed by land use and management activities during the next inventory and to track the crop rotation and tillage intensity through three inventories. The approach allows annual rates of change of carbon sequestration from different historic land uses and management to be estimated explicitly for each assessment point based on the effect of previous land use and management. The model generates 3524 unique annual SOC sequestration rates that vary by land use and management history on U.S. agricultural land based on the 30 SOC stock reference values provided by IPCC documentation. An average of 0.33 Mg C ha -1 yr -1 is stored when cropland that was conventionally tilled in two previous inventories is set-aside in the third inventory, but only 0.14 Mg C ha -1 yr -1 when it is conventionally tilled in the first inventory and no-till in the second inventory before it is set aside. Incorporating a winter cover on cropland that was conventionally tilled in the first inventory and no-till in the second and third inventories is estimated to store 0.49 Mg C ha -1 yr -1, but could store 0.81 Mg C ha -1 yr -1 if it was conventionally tilled in the first two inventories and under no-till in the final inventory. Cropland under conventional tillage in the first two inventories and no-till the final inventory could store an average of 0.34 Mg C ha -1 yr -1, but cropland under conventional tillage in the first, reduced tillage in the second, and no-till in the third inventory is estimated to store 0.19 Mg C ha -1 yr -1. The detailed annual rates of SOC stock change estimated using the approach is useful for economic or other analyses and for policymakers.
  • Authors:
    • Guzman, J. A.
    • Steiner, J. L.
    • Garbrecht, J. D.
    • Grimsley, D. L.
    • Fiebrich, C. A.
    • Starks, P. J.
    • Moriasi, D. N.
  • Source: Journal of Environmental Quality
  • Volume: 43
  • Issue: 4
  • Year: 2014
  • Summary: Hydrologic, watershed, water resources, and climate-related research conducted by the USDA-ARS Grazinglands Research Laboratory (GRL) are rooted in events dating back to the 1930s. In 1960, the 2927-km 2 Southern Great Plains Research Watershed (SGPRW) was established to study the effectiveness of USDA flood control and soil erosion prevention programs. The size of the SGPRW was scaled back in 1978, leaving only the 610-km 2 Little Washita River Experimental Watershed (LWREW) to be used as an outdoor hydrologic research laboratory. Since 1978, the number of measurement sites and types of instruments used to collect meteorologic and soil climate data have changed on the LWREW. Moreover, a second research watershed, the 786-km 2 Fort Cobb Reservoir Experimental Watershed (FCREW), was added in 2004 to the GRL's outdoor research laboratories to further study the effects of agricultural conservation practices on selected environmental endpoints. We describe the SGPREW, FCREW, and LWREW and the meteorologic measurement network (historic and present) deployed on them, provide descriptions of measurements, including information on accuracy and calibration, quality assurance measures (where known), and data archiving of the present network, give examples of data products and applications, and provide information for the public and research communities regarding access and availability of both the historic and recent data from these watersheds.
  • Authors:
    • Nalley, L. L.
    • Barkley, A.
    • Tack, J.
  • Source: Climatic Change
  • Volume: 125
  • Issue: 3-4
  • Year: 2014
  • Authors:
    • Verhoeven, E.
    • Six, J.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 191
  • Year: 2014
  • Summary: Biochar amendment to soil has been proposed as a mechanism to mitigate climate change through an array of mechanisms; one being the mitigation of soil nitrous oxide (N 2O) emissions. Yet the extent and mechanisms through which this may be achieved in temperate agroecosystems is uncertain. We used a pine chip biochar produced at a moderate temperature (550°C, PC biochar) and a walnut shell biochar produced at a higher temperature (900°C, WS biochar). Biochar was applied at 10 Mg ha -1 to a working commercial wine grape system in North-Central California. The effects of biochar were assessed over two years at two distinct functional locations: the berm and row, which differed in N application and irrigation. N 2O emissions and ancillary soil properties (NH 4+, NO 3, water filled pore space (WFPS), and pH) were closely monitored following management and precipitation events. Soil bulk density, cover crop yield and soil C and N were measured annually to address longer term changes in cropping system and soil properties. In the PC biochar treatment, annual cumulative N 2O emissions were significantly higher than the control treatment each year ( p<0.05); 4.141.14 kg N 2O-N ha -1 yr -1 versus 2.000.66 kg N 2O-N ha -1 yr -1 in year one, and 4.240.74 kg N 2O-N ha -1 yr -1 versus 1.600.28 kg N 2O-N ha -1 yr -1 in year two. Emissions of N 2O in the WS biochar treatment were also higher than the control each year, but differences were not significant. The effect of biochar on N 2O emissions was more pronounced in the row location where annual emissions were significantly higher than the control in one and both years for the WS and PC biochars, respectively ( p<0.05). In the PC biochar treatment, we observed increased N 2O emissions at both functional locations, however increases were more pronounced in the row location where they were in part attributable to increased cover crop N inputs. Differences between treatments in NH 4+, NO 3- and WFPS were mostly not significant. The WS biochar significantly raised soil pH relative to the control ( p<0.05), however in the berm location only, and increased soil pH in this treatment did not correspond to changes in N 2O emissions. Since neither biochar amendment reduced N 2O emissions, our results demonstrate the need to evaluate N 2O emissions at a cropping system scale (e.g. encompassing changes in N inputs and cycling) and in systems where nitrification processes may dominate emissions.
  • Authors:
    • Sainju, Upendra M.
    • Wang, Jun
  • Source: PLOS ONE
  • Volume: 9
  • Issue: 8
  • Year: 2014
  • Summary: Soil labile C and N fractions can change rapidly in response to management practices compared to non-labile fractions. High variability in soil properties in the field, however, results in nonresponse to management practices on these parameters. We evaluated the effects of residue placement (surface application [or simulated no-tillage] and incorporation into the soil [or simulated conventional tillage]) and crop types (spring wheat [Triticum aestivum L.], pea [Pisum sativum L.], and fallow) on crop yields and soil C and N fractions at the 0-20 cm depth within a crop growing season in the greenhouse and the field. Soil C and N fractions were soil organic C (SOC), total N (STN), particulate organic C and N (POC and PON), microbial biomass C and N (MBC and MBN), potential C and N mineralization (PCM and PNM), NH4-N, and NO3-N concentrations. Yields of both wheat and pea varied with residue placement in the greenhouse as well as in the field. In the greenhouse, SOC, PCM, STN, MBN, and NH4-N concentrations were greater in surface placement than incorporation of residue and greater under wheat than pea or fallow. In the field, MBN and NH4-N concentrations were greater in no-tillage than conventional tillage, but the trend reversed for NO3-N. The PNM was greater under pea or fallow than wheat in the greenhouse and the field. Average SOC, POC, MBC, PON, PNM, MBN, and NO3-N concentrations across treatments were higher, but STN, PCM and NH4-N concentrations were lower in the greenhouse than the field. The coefficient of variation for soil parameters ranged from 2.6 to 15.9% in the greenhouse and 8.0 to 36.7% in the field. Although crop yields varied, most soil C and N fractions were greater in surface placement than incorporation of residue and greater under wheat than pea or fallow in the greenhouse than the field within a crop growing season. Short-term management effect on soil C and N fractions were readily obtained with reduced variability under controlled soil and environmental conditions in the greenhouse compared to the field. Changes occurred more in soil labile than non-labile C and N fractions in the greenhouse than the field.
  • Authors:
    • Group Author(s): USA, U. S. Department of Agriculture
  • Source: Renewable Resources Journal
  • Volume: 28
  • Issue: 1
  • Year: 2014
  • Summary: This paper an excerpt from Technical Bulletin of the U.S. Department of Agriculture's (USDA's) Agricultural Research Service Climate Change Program Office describes climate change and agriculture in the USA. The paper discusses the following topics: crop and livestock response to changing climate, effects of climate change to soil and water, and extreme events. Further, the paper also enumerates a number of adaptation measures to address climate change and identifies research needs to improve understanding of the exposure, sensitivity, and adaptive capacity of the US agriculture to climate change.
  • Authors:
    • Anderson, S. H.
    • Udawatta, R. P.
    • Adhikari, P.
  • Source: Soil Science Society of America Journal
  • Volume: 78
  • Issue: 6
  • Year: 2014
  • Summary: Although prairies and conservation buffers are becoming popular to improve soil properties and environmental quality, very little is known about their influence on soil thermal properties. This study compared and quantified thermal conductivity (l), thermal diffusivity (D), and volumetric heat capacity (C) of prairies (Tucker Prairie [TP] and Prairie Fork [PF]), conservation buffers (grass buffers [GB] and agroforestry buffers [AGF]), and corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation (COS) land uses in Missouri. Core and bulk soils were collected at 10-cm depth increments. Soil thermal properties and water characteristic curves were determined at 0, -33, -100, and -300 kPa pressures. Additionally, soil organic C (SOC) and bulk density (BD) were also determined. The results showed that SOC was negatively correlated with l and D and positively correlated with C. Significantly higher values of SOC and lower BD were observed for AGF, TP, GB, and PF than COS. Similarly, l and D were significantly higher and C was lower under COS than the prairies and conservation buffers. The results suggest that a greater amount of SOC decreases the thermal conductance due to the insulating characteristics of SOC and acts as a barrier to heat transport. Therefore, AGF, TP, GB, and PF had lower thermal conductance to deeper soil depths, which helps to conserve more moisture as well as assist in increasing the longevity of SOC in the soil matrix. Our results imply that buffers and perennial vegetation can help reduce heat flow by increasing the thermal capacity and thereby mitigating climate change.
  • Authors:
    • Morton, L. W.
    • Loy, A.
    • Hobbs, J.
    • Arbuckle, J. G., Jr.
    • Prokopy, L. S.
    • Tyndall, J.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 69
  • Issue: 6
  • Year: 2014
  • Summary: Development of extension and outreach that effectively engage farmers in climate change adaptation and/or mitigation activities can be informed by an improved understanding of farmers' perspectives on climate change and related impacts. This research employed latent class analysis (LCA) to analyze data from a survey of 4,778 farmers from 11 US Corn Belt states. The research focused on two related research questions: (1) to what degree do farmers differ on key measures of beliefs about climate change, experience with extreme weather, perceived risks to agriculture, efficacy, and level of support for public and private adaptive and mitigative action; and (2) are there potential areas of common ground among farmers? Results indicate that farmers have highly heterogeneous perspectives, and six distinct classes of farmers are identified. We label these as the following: the concerned (14%), the uneasy (25%), the uncertain (25%), the unconcerned (13%), the confident (18%), and the detached (5%). These groups of farmers differ primarily in terms of beliefs about climate change, the degree to which they had experienced extreme weather, and risk perceptions. Despite substantial differences on these variables, areas of similarity were discerned on variables measuring farmers' (1) confidence that they will be able to deal with increases in weather variability and (2) support for public and private efforts to help farmers adapt to increased weather variability. These results can inform segmented approaches to outreach that target subpopulations of farmers as well as broader engagement strategies that would reach wider populations. Further, findings suggest that strategies with specific reference to climate change might be most effective in engaging the subpopulations of farmers who believe that climate change is occurring and a threat, but that use of less charged terms such as weather variability would likely be more effective with a broader range of farmers. Outreach efforts that (1) appeal to farmers' problem solving capacity and (2) employ terms such as "weather variability" instead of more charged terms such as "climate change" are more likely to be effective with a wider farmer audience.
  • Authors:
    • Fritz, A.
    • Bowden, R.
    • Bergtold, J.
    • Nalley, L. L.
    • Tack, J.
    • Barkley, A.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 1
  • Year: 2014
  • Summary: Wheat (Triticum aestivum L.) yields in Kansas have increased due to wheat breeding and improved agronomic practices, but are subject to climate and disease challenges. The objective of this research is to quantify the impact of weather, disease, and genetic improvement on wheat yields of varieties grown in 11 locations in Kansas from 1985 to 2011. Wheat variety yield data from Kansas performance tests were matched with comprehensive location-specific disease and weather data, including seasonal precipitation, monthly air temperature, air temperature and solar radiation around anthesis, and vapor pressure deficit (VPD). The results show that wheat breeding programs increased yield by 34 kg ha(-1) yr(-1). From 1985 through 2011, wheat breeding increased average wheat yields by 917 kg ha(-1), or 27% of total yield. Weather was found to have a large impact on wheat yields. Simulations demonstrated that a 1 degrees C increase in projected mean temperature was associated with a decrease in wheat yields of 715 kg ha(-1), or 21%. Weather, diseases, and genetics all had significant impacts on wheat yields in 11 locations in Kansas during 1985 to 2011.