• Authors:
    • Harrington, J. Jr.
    • Hutchinson, S.
    • Knapp, M.
    • Gowda, P. H.
    • Perumal, S.
    • Anandhi, A.
    • Murray, L.
    • Kirkham, M. B.
    • Rice, C. W.
  • Source: Climatic Change
  • Volume: 120
  • Issue: 1-2
  • Year: 2013
  • Summary: Frost indices such as number of frost days (nFDs), number of frost-free days (nFFDs), last spring freeze (LSF), first fall freeze (FFF), and growing-season length (GSL) were calculated using daily minimum air temperature (Tmin) from 23 centennial weather stations across Kansas during four time periods (through 1919, 1920-1949, 1950-1979, and 1980-2009). A frost day is defined as a day with Tmin<0°C. The long - and short-term trends in frost indices were analyzed at monthly, seasonal, and annual timescales. Probability of occurrence of the indices was analyzed at 5%, 25%, 50%, 75%, and 95%. Results indicated a general increase in Tmin from 1900 through 2009 causing a decrease in nFDs. LSF and FFF occurred earlier and later than normal in the year, respectively, thereby resulting in an increase in GSL. In general, northwest Kansas recorded the greatest nFD and lowest Tmin, whereas southeast Kansas had the lowest nFD and highest Tmin; however, the magnitude of the trends in these indices varied with location, time period, and time scales. Based on the long-term records in most stations, LSF occurred earlier by 0.1-1.9 days/decade, FFF occurred later by 0.2-0.9 day/decade, and GSL was longer by 0.1-2.5 day/decade. At the 50% probability level, Independence in the south-eastern part of Kansas had the earliest LSF (6 April), latest FFF (29 October) and longest GSL (207 days). Oberlin (north-western Kansas) recorded the shortest GSL (156 days) and earliest FFF (7 October) had the latest LSF (2 May) at the 50% probability level. A positive correlation was observed for combinations of indices (LSF and GSL) and elevation, whereas a negative correlation was found between FFF and elevation.
  • Authors:
    • Nearing, M.
    • Delgado, J.
    • Rice, C.
  • Source: Advances in Agronomy
  • Volume: 121
  • Year: 2013
  • Summary: The threat of climate change is a great challenge to sustainable land management (USDA-NRCS, 2010a). Several publications have reported that over the last few decades, rainfall intensities have increased in many parts of the world, including in the United States. Without good, productive soils and the ecosystem services provided by them, the survival of our species will be in jeopardy. The future changes in climate that will drive erosion processes will significantly impact soil erosion rates, with higher projected erosion rates for the United States. These higher erosion rates will significantly contribute to lower soil productivity, lower soil organic matter content, lower soil quality, and higher rates of nutrient loss that will contribute to a reduction in the inherent soil fertility that is so important for maintaining viable economic systems and sustainability. These same hydrological changes will also include the occurrence of occasional droughts, and for some regions, such as the southwestern United States, projections suggest that there will be a decrease in precipitation and a drier region, which will have negative effects on plant productivity and increase the potential for wind erosion. Farmer management adaptations and use of conservation practices to adapt to a changing climate (e.g., no-till practices, crop rotations, precision conservation, crop selection and dates of planting, harvest, and tillage) have the potential to greatly reduce soil erosion rates. Conservation practices will be key and must be used as strategies for adaptation to climate change impacts on the soil resource. Examples of key strategies are the use of conservation tillage, management of crop rotations and crop residue (including use of cover crops where viable), management of livestock grazing intensities, improved management of irrigation systems, use of technologies, and precision conservation. Many other conservation practices also have the potential to reduce much or all of the potential acceleration of soil erosion rates that may occur under a change in climate that will bring more total rainfall with higher intensity rainfall events, or a change to a drier climate that will potentially bring higher wind erosion rates. One important adaptation practice will be to consider projected spatial changes in the hydrological cycle, such as wetter and drier regions, and periods of drought. This could help in the development and/or implementation of soil and water conservation policies that consider temporal and spatial effects from climate change at the regional level. These policies should also consider conservation practices that contribute to increased water-holding capacity in the soil profile, improved drainage practices, and the development of new crop varieties and cropping systems that are more resistant to drought.
  • Authors:
    • Rappaport, A. G.
    • Mitra, S.
    • Francis, B.
    • Harris, R.
    • Thomson, A. M.
    • Reeves, J. B.
    • Ebinger, M. H.
    • Wielopolski, L.
    • Rice, C. W.
    • Izaurralde, R. C.
    • Etchevers, J. D.
    • Sayre, K. D.
    • Govaerts, B.
    • McCarty, G. W.
  • Source: PLOS ONE
  • Volume: 8
  • Issue: 1
  • Year: 2013
  • Summary: Three advanced technologies to measure soil carbon (C) density (g C m -2) are deployed in the field and the results compared against those obtained by the dry combustion (DC) method. The advanced methods are: (a) Laser Induced Breakdown Spectroscopy (LIBS), (b) Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS), and (c) Inelastic Neutron Scattering (INS). The measurements and soil samples were acquired at Beltsville, MD, USA and at Centro International para el Mejoramiento del Maiz y el Trigo (CIMMYT) at El Batan, Mexico. At Beltsville, soil samples were extracted at three depth intervals (0-5, 5-15, and 15-30 cm) and processed for analysis in the field with the LIBS and DRIFTS instruments. The INS instrument determined soil C density to a depth of 30 cm via scanning and stationary measurements. Subsequently, soil core samples were analyzed in the laboratory for soil bulk density (kg m -3), C concentration (g kg -1) by DC, and results reported as soil C density (kg m -2). Results from each technique were derived independently and contributed to a blind test against results from the reference (DC) method. A similar procedure was employed at CIMMYT in Mexico employing but only with the LIBS and DRIFTS instruments. Following conversion to common units, we found that the LIBS, DRIFTS, and INS results can be compared directly with those obtained by the DC method. The first two methods and the standard DC require soil sampling and need soil bulk density information to convert soil C concentrations to soil C densities while the INS method does not require soil sampling. We conclude that, in comparison with the DC method, the three instruments (a) showed acceptable performances although further work is needed to improve calibration techniques and (b) demonstrated their portability and their capacity to perform under field conditions.
  • Authors:
    • McGowan, A.
    • Lindsley, A.
    • Arango, M.
    • Rice, C. W.
    • Jumpponen, A.
    • Bottomley, P. J.
    • Zeglin, L. H.
    • Mfombep, P.
    • Myrold, D. D.
  • Source: ECOLOGY
  • Volume: 94
  • Issue: 10
  • Year: 2013
  • Summary: Climate change models predict that future precipitation patterns will entail lower-frequency but larger rainfall events, increasing the duration of dry soil conditions. Resulting shifts in microbial C cycling activity could affect soil C storage. Further, microbial response to rainfall events may be constrained by the physiological or nutrient limitation stress of extended drought periods; thus seasonal or multiannual precipitation regimes may influence microbial activity following soil wet-up. We quantified rainfall-driven dynamics of microbial processes that affect soil C loss and retention, and microbial community composition, in soils from a long-term (14-year) field experiment contrasting "Ambient" and "Altered" (extended intervals between rainfalls) precipitation regimes. We collected soil before, the day following, and five days following 2.5-cm rainfall events during both moist and dry periods (June and September 2011; soil water potential=-0.01 and -0.83 MPa, respectively), and measured microbial respiration, microbial biomass, organic matter decomposition potential (extracellular enzyme activities), and microbial community composition (phospholipid fatty acids). The equivalent rainfall events caused equivalent microbial respiration responses in both treatments. In contrast, microbial biomass was higher and increased after rainfall in the Altered treatment soils only, thus microbial C use efficiency (CUE) was higher in Altered than Ambient treatments (0.700.03 >0.460.10). CUE was also higher in dry (September) soils. C-acquiring enzyme activities (beta-glucosidase, cellobiohydrolase, and phenol oxidase) increased after rainfall in moist (June), but not dry (September) soils. Both microbial biomass C:N ratios and fungal: bacterial ratios were higher at lower soil water contents, suggesting a functional and/or population-level shift in the microbiota at low soil water contents, and microbial community composition also differed following wet-up and between seasons and treatments. Overall, microbial activity may directly (C respiration) and indirectly (enzyme potential) reduce soil organic matter pools less in drier soils, and soil C sequestration potential (CUE) may be higher in soils with a history of extended dry periods between rainfall events. The implications include that soil C loss may be reduced or compensated for via different mechanisms at varying time scales, and that microbial taxa with better stress tolerance or growth efficiency may be associated with these functional shifts.
  • Authors:
    • Robertson, A. E.
    • Mallarino, A. P.
    • Lenssen, A. W.
    • Hodgson, E. W.
    • Helmers, M. J.
    • Hart, C. E.
    • Hanna, H. M.
    • Guzman, J. G.
    • Elmore, R. W.
    • Al-Kaisi, M. M.
    • Sawyer, J. E.
  • Source: Journal of Soil and Water Conservation
  • Volume: 68
  • Issue: 1
  • Year: 2013
  • Authors:
    • Gramig, B. M.
    • Clawson, R. A.
    • Andrews, A. C.
    • Raymond, L.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 68
  • Issue: 6
  • Year: 2013
  • Summary: In this paper, framing effects are investigated in a new context: farmer decision making about conservation tillage practices. Primary hypotheses include the following: (1) frames (i.e., different arguments about or conceptions of an issue) portraying conservation tillage as "profitable" will generate more interest in the tillage technique among farmers than a control frame presenting only basic information; (2) frames discussing potential payments for "environmental benefits" will generate more positive attitudes than frames discussing payment for "storing carbon (C)" to limit climate change; and (3) framing effects will vary based on subjects' prior beliefs and experiences. These hypotheses were tested using a survey-based experiment administered to a national sample of row-crop farmers. Contrary to expectations, the profit frame and both payment frames had no effect on farmers' interest in conservation tillage across our entire sample. Consistent with the third hypothesis, however, a negative framing effect was found for the profit frame on nonadopters who reported no use of no-till in the past two years. These results support the argument regarding the importance of prior beliefs in reactions to frames. They also suggest the possibility of modest financial payments "crowding out" intrinsic motivations for contributions to public goods such as soil conservation. From a policy perspective, these findings also suggest the relative inefficacy of offers of modest conservation payments or profitability frames in promoting no-till farming, especially among nonadopters, and the need to find alternative frames that avoid reinforcing an argument that nonadopters appear to have already considered and rejected.
  • Authors:
    • Arbuckle, J. G., Jr.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 68
  • Issue: 2
  • Year: 2013
  • Summary: Conservation Compliance, which since its inception in 1985 has led to substantial reductions in soil erosion by linking eligibility for some Farm Bill programs to erosion control on highly erodible land, is at a critical juncture. Agricultural economic and budget factors have reduced the effectiveness of compliance incentives, and numerous groups are calling for enhancement of incentives and/or for extension of compliance beyond erosion control to cover concerns such as water quality impairment. This study analyzed survey data measuring Iowa farmers' support for four increasingly stringent Conservation Compliance scenarios ranging from the current configuration to a requirement that all farmers control nutrient runoff regardless of participation in Farm Bill programs. Overall, the results indicate that Iowa farmers have a generally positive view of Conservation Compliance policy, both as currently configured and in potentially more stringent and extensive forms. Farmers with stronger conservationist identities and attitudes were more likely to endorse increasing the scope and stringency of Conservation Compliance, while farmers who expressed greater levels of concern about the property rights implications of government intervention and those with more productivist orientations were less likely to support such policy changes. Taken as a whole, the results suggest that most Iowa farmers think that Conservation Compliance is a good idea, should be continued, and should be extended to more farmers and other resource concerns.
  • Authors:
    • Blanco-Canqui, H.
    • Schlegel, A. J.
  • Source: Web Of Knowledge
  • Volume: 42
  • Issue: 3
  • Year: 2013
  • Summary: Inorganic fertilizers are widely used for crop production, but their long-term impacts on soil organic carbon (SOC) pools and soil physical attributes are not fully understood. We studied how half a century of N application at 0, 45, 90, 134, 179, and 224 kg ha -1 and P application at 0, 20, and 40 kg ha -1 (since 1992) affected SOC pools and soil structural and hydraulic parameters in irrigated continuous corn ( Zea mays L.) under conventional till on an Aridic Haplustoll in the central Great Plains. Application of 45, 90, 134, 179, and 224 kg N ha -1 increased the SOC pool by 4.6, 6.8, 7.6, 7.9, and 9.7 Mg ha -1, respectively, relative to nonfertilized plots in the 0- to 45-cm depth. Application of 20 kg P ha -1 increased the SOC pool by 2.9 Mg ha -1 in the 0- to 30-cm depth. The highest N rate increased the SOC pool by 195 kg ha -1 yr -1. The C gains may be, however, offset by the C hidden costs of N fertilization. Application of >45 kg N ha -1 reduced the proportion of soil macroaggregates (>0.25 mm) in the 7.5- to 30-cm depth. Fertilization did not affect hydraulic properties, but application of ≥90 kg N ha -1 slightly increased aggregate water repellency. An increase in SOC concentration did not increase the mean weight diameter of wet aggregates ( r=0.1; P>0.10), but it slightly increased aggregate water repellency ( r=0.5; P<0.005). Overall, long-term inorganic fertilization to irrigated corn can increase SOC pool, but it may reduce soil structural stability.
  • Authors:
    • Shaver, T. M.
    • Mamo, M.
    • Drijber, R. A.
    • Wortmann, C. S.
    • Shapiro, C. A.
    • Blanco-Canqui, H.
    • Ferguson, R. B.
  • Source: Web Of Knowledge
  • Volume: 68
  • Issue: 5
  • Year: 2013
  • Authors:
    • Bonta, J. V.
  • Source: Journal of Soil and Water Conservation
  • Volume: 68
  • Issue: 3
  • Year: 2013
  • Summary: Quantifying magnitudes and frequencies of rainless times between storms (TBS), or storm occurrence, is required for generating continuous sequences of precipitation for modeling inputs to small watershed models for conservation studies. Two parameters characterize TBS, minimum TBS (MTBS) and average TBS (ATBS) both vary monthly and are calculated by assuming TBS follows an exponential distribution. Detecting changes in these parameters due to climate is important for precipitation and climate studies at short time and small spatial scales, but there are issues with depth resolution of precipitation data that must first be investigated. Precipitation data having one-minute temporal and 0.25 mm (0.01 in) depth resolutions from the UDSA Agricultural Research Service North Appalachian Experimental Watershed (NAEW) at Coshocton, Ohio, were used to determine the spatial variability and consistency of estimates over the 425 ha (1,050 ac) facility and the impacts of coarsening the depth resolution of data 10 times to 2.54 mm (0.1 in). The magnitudes and trends of changes in MTBS and ATBS are determined for three rain gauges over the NAEW and extended to other gauges in the Ohio region. Approximately 5,800 parameter pairs were computed for different data configurations. Small spatial scale, NAEW high-resolution precipitation data shows consistent MTBS and ATBS long-term values for each month but more variability in estimates for MTBS than ATBS. Climate change trends for MTBS and ATBS are not apparent and generally consistent for different NAEW gauges, except for November when all gauges were consistently significant for ATBS. There is a weak indication that the fall months may be affected by significant shortening of ATBS at the NAEW and in northeastern Ohio due to climate change, but more data are needed. An imposed, coarser NAEW data resolution results in consistent no-trend indications for MTBS, but not for ATBS. The coarse-resolution data may not be adequate to characterize TBS for investigating changes due to climate change unless more data preparation is performed, such as identifying and excluding dry times when precipitation may have occurred. Precipitation records with mixed resolution data cannot be used to detect climate changes of dry periods. More data and data preparation are needed to arrive at firm conclusions regarding climate change effects on TBS in Ohio.