• 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:
    • 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:
    • Breedveld, G. D.
    • Martinsen, V.
    • Field, J. L.
    • Sparrevik, M.
    • Cornelissen, G.
  • Source: Environmental Science and Technology
  • Volume: 47
  • Issue: 3
  • Year: 2013
  • Summary: Biochar amendment to soil is a potential technology for carbon storage and climate change mitigation. It may, in addition, be a valuable soil fertility enhancer for agricultural purposes in sandy and/or weathered soils. A life cycle assessment including ecological, health and resource impacts has been conducted for field sites in Zambia to evaluate the overall impacts of biochar for agricultural use. The life cycle impacts from conservation farming using cultivation growth basins and precision fertilization with and without biochar addition were in the present study compared to conventional agricultural methods. Three different biochar production methods were evaluated: traditional earth-mound kilns, improved retort kilns, and micro top-lit updraft (TLUD) gasifier stoves. The results confirm that the use of biochar in conservation farming is beneficial for climate change mitigation purposes. However, when including health impacts from particle emissions originating from biochar production, conservation farming plus biochar from earth-mound kilns generally results in a larger negative effect over the whole life cycle than conservation farming without biochar addition. The use of cleaner technologies such as retort kilns or TLUDs can overcome this problem, mainly because fewer particles and less volatile organic compounds, methane and carbon monoxide are emitted. These results emphasize the need for a holistic view on biochar use in agricultural systems. Of special importance is the biochar production technique which has to be evaluated from both environmental/climate, health and social perspectives.
  • Authors:
    • Lal, R.
    • Stavi, I.
  • Source: Agronomy for Sustainable Development
  • Volume: 33
  • Issue: 1
  • Year: 2013
  • Summary: Expansion of agricultural land use has increased emission of greenhouse gases, exacerbating climatic changes. Most agricultural soils have lost a large portion of their antecedent soil organic carbon storage, becoming a source of atmospheric carbon-dioxide. In addition, agricultural soils can also be a major source of nitrous oxide and methane. Adoption of conservation agricultural practices may mitigate some of the adverse impacts of landuse intensification. However, optimal implementation of these practices is not feasible under all physical and biotic conditions. Of a wide range of conservation practices, the most promising options include agroforestry systems and soil application of biochar, which can efficiently sequester large amounts of carbon over the long-run. In addition, these practices also increase agronomic productivity and support a range of ecosystem services. Payments to farmers and land managers for sequestrating carbon and improving ecosystem services is an important strategy for promoting the adoption of such practices, aimed at mitigating climate change while decreasing environmental footprint of agriculture and sustaining food security.
  • Authors:
    • Paustian, K.
    • Ngugi, M. K.
    • Suddick, E. C.
    • Six, J.
  • Source: California Agriculture
  • Volume: 67
  • Issue: 3
  • Year: 2013
  • Summary: California growers could reap financial benefits from the low-carbon economy and cap-and-trade system envisioned by the state's AB 32 law, which seeks to lower greenhouse gas emissions statewide. Growers could gain carbon credits by reducing greenhouse gas emissions and sequestering carbon through reduced tillage and increased biomass residue incorporation. First, however, baseline stocks of soil carbon need to be assessed for various cropping systems and management practices. We designed and set up a pilot soil carbon and land-use monitoring network at several perennial cropping systems in Northern California. We compared soil carbon content in two vineyards and two orchards (walnut and almond), looking at conventional and conservation management practices, as well as in native grassland and oak woodland. We then calculated baseline estimates of the total carbon in almond, wine grape and walnut acreages statewide. The organic walnut orchard had the highest total soil carbon, and no-till vineyards had 27% more carbon in the surface soil than tilled vineyards. We estimated wine grape vineyards are storing significantly more soil carbon per acre than almond and walnut orchards. The data can be used to provide accurate information about soil carbon stocks in perennial cropping systems for a future carbon trading system.
  • Authors:
    • Maynard, N. G.
    • Huntington, H. P.
    • Chapin, F. S.
    • Tom, S.
    • Pungowiyi, C.
    • Huntington, O. H.
    • Cochran, P.
    • Trainor, S. F.
  • Source: Research Article
  • Volume: 120
  • Issue: 3
  • Year: 2013
  • Summary: Despite a keen awareness of climate change, northern Indigenous Peoples have had limited participation in climate-change science due to limited access, power imbalances, and differences in worldview. A western science emphasis on facts and an indigenous emphasis on relationships to spiritual and biophysical components indicate important but distinct contributions that each knowledge system can make. Indigenous communities are experiencing widespread thawing of permafrost and coastal erosion exacerbated by loss of protective sea ice. These climate-induced changes threaten village infrastructure, water supplies, health, and safety. Climate-induced habitat changes associated with loss of sea ice and with landscape drying and extensive wildfires interact with northern development to bring both economic opportunities and environmental impacts. A multi-pronged approach to broadening indigenous participation in climate-change research should: 1) engage communities in designing climate-change solutions; 2) create an environment of mutual respect for multiple ways of knowing; 3) directly assist communities in achieving their adaptation goals; 4) promote partnerships that foster effective climate solutions from both western and indigenous perspectives; and 5) foster regional and international networking to share climate solutions.
  • Authors:
    • Iqbal,Javed
    • Nelson,Jim A.
    • McCulley,Rebecca L.
  • Source: Plant and Soil
  • Volume: 364
  • Issue: 1-2
  • Year: 2013
  • Summary: Novel fungal endophyte (Neotyphodium coenophialum; Latch, Christensen and Samuels; Glenn, Bacon, and Hanlin) genotypes in symbiosis with tall fescue (Lolium arundinaceum; Schreb. Darbysh.) have been recently introduced to agricultural seed markets. These novel endophytes do not produce the full suite of toxins that the 'common toxic' form does, and therefore, may not have the same consequences on plant and soil processes. Here, we evaluated the effects of endophyte presence and genotype on ecosystem processes of tall fescue stands. We quantified the effects of the presence of the common toxic endophyte (CT), two novel endophyte genotypes (AR-542, AR-584), no endophyte (endophyte free, E-), and a mixture of all endophyte statuses (mix) within a single genotype of tall fescue (PDF) on various soil and plant parameters. Endophyte presence and genotype affected tall fescue cover and plant species diversity: cover-CT, AR-542, AR -584, mix > E- and species diversity-E- > AR-542, AR -584 > CT, mix. Most measured soil parameters had significant endophyte effects. For example, higher fluxes of soil CO2 and N2O were measured from stands of AR-542 than from the other endophyte treatments. These results indicate that endophyte presence and genetic identity are important in understanding the ecosystem-scale effects of this agronomically important grass-fungal symbiosis.
  • Authors:
    • Novara,Agata
    • Gristina,Luciano
    • La Mantia,Tommaso
    • Ruehl,Juliane
  • Source: Geoderma
  • Volume: 193-194
  • Year: 2013
  • Summary: Clarifying which factors cause an increase or decrease in soil organic carbon (SOC) after agricultural abandonment requires integration of data on the temporal dynamics of the plant community and SOC. A chronosequence of abandoned vineyards was studied on a volcanic island (Pantelleria, Italy). Vegetation in the abandoned fields was initially dominated by annual and perennial herbs, then by Hyparrhenia hirta (L.) Stapf, and finally by woody communities. As a consequence, the dominant photosynthetic pathway changed from C-3 to C-4 and then back to C-3. Conversion of a plant community dominated by one photosynthetic pathway to another changes the C-13/C-12 ratio of inputs to SOC. Using the time since abandonment and the shift in belowground delta C-13 of SOC relative to the aboveground delta C-13 plant community, we estimated C-3-C and C-4-C changes during secondary succession. SOC content (g kg(-1)) increased linearly (R-2=0.89 and 0.73 for 0-15 and 15-30 cm soil depth) with the age of abandonment, increasing from 12 g kg(-1) in cultivated vineyards to as high as 26 g kg(-1) in the last stage of the succession. delta C-13 increased in the bulk soil and its three aggregate fractions (> 250,250-25, and < 25 mu m) during succession, but the effect of soil depth and its interaction with succession age were significant only for soil aggregate fractions. Polynomial curves described the change in delta C-13 over the chronosequence for both depths. delta C-13 in the bulk soil had increased from -28 parts per thousand. to -24 parts per thousand. by 35 years after abandonment for both depths but then decreased to -26 parts per thousand. at 60 years after abandonment (corresponding with maturity of the woody plant community). Overall, the results indicate that abandoned vineyards on volcanic soil in a semi-arid environment are C sinks and that C storage in these soils is closely related to plant succession. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Smith,Lydia J.
    • Torn,Margaret S.
  • Source: Climatic Change
  • Volume: 118
  • Issue: 1
  • Year: 2013
  • Summary: Terrestrial biological atmospheric carbon dioxide removal (BCDR) through bioenergy with carbon capture and storage (BECS), afforestation/reforestation, and forest and soil management is a family of proposed climate change mitigation strategies. Very high sequestration potentials for these strategies have been reported, but there has been no systematic analysis of the potential ecological limits to and environmental impacts of implementation at the scale relevant to climate change mitigation. In this analysis, we identified site-specific aspects of land, water, nutrients, and habitat that will affect local project-scale carbon sequestration and ecological impacts. Using this framework, we estimated global-scale land and resource requirements for BCDR, implemented at a rate of 1 Pg C y(-1). We estimate that removing 1 Pg C y(-1) via tropical afforestation would require at least 7 x 10(6) ha y(-1) of land, 0.09 Tg y(-1) of nitrogen, and 0.2 Tg y(-1) of phosphorous, and would increase evapotranspiration from those lands by almost 50 %. Switchgrass BECS would require at least 2 x 10(8) ha of land (20 times U.S. area currently under bioethanol production) and 20 Tg y(-1) of nitrogen (20 % of global fertilizer nitrogen production), consuming 4 x 10(12) m(3) y(-1) of water. While BCDR promises some direct (climate) and ancillary (restoration, habitat protection) benefits, Pg C-scale implementation may be constrained by ecological factors, and may compromise the ultimate goals of climate change mitigation.