Soil Degradation: Will Humankind Ever Learn?

Citation: Karlen, D. L., & Rice, C. W. (2015). Soil Degradation: Will Humankind Ever Learn? Sustainability, 7(9), 12490-12501. doi:10.3390/su70912490Soil degradation is a global problem caused by many factors including excessive tillage, inappropriate crop rotations, excessive grazing or crop residue removal, deforestation, mining, construction and urban sprawl. To meet the needs of an expanding global population, it is essential for humankind to recognize and understand that improving soil health by adopting sustainable agricultural and land management practices is the best solution for mitigating and reversing current soil degradation trends. This research editorial is intended to provide an overview for this Special Issue of Sustainability that examines the global problem of soil degradation through reviews and recent research studies addressing soil health in Africa, Australia, China, Europe, India, North and South America, and Russia. Two common factorssoil erosion and depletion of soil organic matter (SOM)emerge as consistent indicators of how the thin layer covering the planet that stands between us and starvation is being degraded. Soil degradation is not a new problem but failing to acknowledge, mitigate, and remediate the multiple factors leading to it is no longer a viable option for humankind. We optimistically conclude that the most promising strategies to mitigate soil degradation are to select appropriate land uses and improve soil management practices so that SOM is increased, soil biology is enhanced, and all forms of erosion are reduced. Collectively, these actions will enable humankind to take care of the soil so it can take care of us.Soil degradation is a global problem caused by many factors including excessive tillage, inappropriate crop rotations, excessive grazing or crop residue removal, deforestation, mining, construction and urban sprawl. To meet the needs of an expanding global population, it is essential for humankind to recognize and understand that improving soil health by adopting sustainable agricultural and land management practices is the best solution for mitigating and reversing current soil degradation trends. This research editorial is intended to provide an overview for this Special Issue of Sustainability that examines the global problem of soil degradation through reviews and recent research studies addressing soil health in Africa, Australia, China, Europe, India, North and South America, and Russia. Two common factors—soil erosion and depletion of soil organic matter (SOM)—emerge as consistent indicators of how “the thin layer covering the planet that stands between us and starvation” is being degraded. Soil degradation is not a new problem but failing to acknowledge, mitigate, and remediate the multiple factors leading to it is no longer a viable option for humankind. We optimistically conclude that the most promising strategies to mitigate soil degradation are to select appropriate land uses and improve soil management practices so that SOM is increased, soil biology is enhanced, and all forms of erosion are reduced. Collectively, these actions will enable humankind to “take care of the soil so it can take care of us”

Snow and ice melt flow features on Devon Island, Nunavut, Arctic Canada as possible analogs for recent slope flow features on Mars

Based on morphologic and contextual analogs from Devon Island, Arctic Canada, the recent martian slope flow features reported by Malin and Edgett are reinterpreted as being due not necessarily to groundwater seepage but possibly to snow or ice melt

A Risk Analysis of Carbon Sequestration in Claypan Soil with Conservation Tillage Systems and Nitrogen Fertilizers for Grain Sorghum and Soybean

Replaced with revised version of paper 02/15/06.carbon sequestration, carbon credits, nitrogen, risk, tillage, Crop Production/Industries, Risk and Uncertainty, Q12,

AN ECONOMIC AND RISK ANALYSIS OF THE EFFECTS OF TILLAGE AND NITROGEN SOURCE ON SOIL CARBON SEQUESTRATION IN CORN PRODUCTION

The economic potential of no-tillage versus conventional tillage to sequester soil carbon using either commercial nitrogen or manure for continuous corn production is evaluated. Results indicate which system provides the highest net returns, which system is preferred by risk averse decision makers, and the price of carbon credits under alternative risk aversion preferences.Risk and Uncertainty,

An Economic Analysis of Carbon Sequestration for Wheat and Grain Sorghum Production in Kansas

This study examined the economic potential with and without carbon credit payments of two crop and tillage systems in South Central Kansas that could reduce carbon dioxide emissions and sequester carbon in the soil. Experiment station cropping practices, yield data, and soil carbon data for continuously cropped wheat and grain sorghum produced with conventional tillage and no-tillage from1986 to 1995 were used to determine soil carbon changes and to develop enterprise budgets to determine expected net returns for a typical dryland farm in South Central Kansas. No-till had lower net returns because of lower yields and higher overall costs. Both crops produced under no-till had higher annual soil C gains than under conventional tillage. Carbon credit payments may be critical to induce farm managers to use cropping practices, such as no-till, that sequester soil carbon. The carbon credit payments needed will be highly dependent on cropping system production costs, especially herbicide costs, which substitute for tillage as a means of weed control. The C values estimated in this study that would provide an incentive to adopt no-tillage range from $0 to$95.991ton/year, depending upon the assumption about herbicide costs. In addition, if producers were compensated for other environmental benefits associated with no-till, carbon credits could be reduced.carbon credit value, carbon sequestration, grain sorghum, no-tillage, wheat, Crop Production/Industries,

Derived Carbon Credit Values for Carbon Sequestration: Do CO2 Emissions From Production Inputs Matter?

Environmental Economics and Policy,

DERIVED CARBON CREDIT VALUES FOR CARBON SEQUESTRATION: DO CO2 EMISSIONS FROM PRODUCTION INPUTS MATTER ?

An economic analysis was conducted involving wheat and grain sorghum production systems that affect carbon dioxide emissions and sequester soil carbon. Parameters examined were expected net returns, changes in net carbon sequestered and the value of carbon credits necessary to equate net returns from systems that sequester more carbon to those that sequester less with and without adjustments for CO2 emissions from production inputs. Evaluations were based on experiment station cropping practices, yield, and soil carbon data for continuously cropped and rotated wheat and grain sorghum produced with conventional and no-tillage. No-till had lower net returns because of lower yields and higher overall costs. Both crops produced under no-till had higher annual soil C gains than under conventional tillage. However, no-till systems had higher total atmospheric emissions of C from production inputs. The differences were relatively small. The C values estimated in this study that would equate net returns of no-tillage to conventional tillage range from $7.82 to$58.69/ton/yr when C emissions from production inputs were subtracted from soil carbon sequestered and $7.79 to$54.99/ton/yr when atmospheric emissions were not considered.Environmental Economics and Policy,

Metabolism of labeled organic nitrogen in soil: regulation by inorganic nitrogen

Includes bibliographical references (page 773).Regulation of organic N metabolism by inorganic N availability was investigated in short-term laboratory incubations of soil. A 14C-, 15N-labeled organic N substrate was produced by growing Pseudomonas stutzeri in labeled media and isolating a cytoplasmic fraction. This was added to soils that had been preincubated with glucose or glucose plus NH+4 to induce conditions of N deficiency or sufficiency. Regulation by inorganic N was indicated by stimulated proteolytic enzyme activity and greater initial rates of cytoplasmic 14C mineralization in N deficient soils. However, effects of N deficiency on 14C mineralization persisted for no more than 24 h. Preinduced N deficiency significantly decreased the extent of 15N mineralized from cytoplasmic N. Mineralization of 14C from leucine added to soil was similarly affected by N availability, yet 14C-glutamate mineralization was apparently unaffected. In another experiment labeled cytoplasm was added simultaneously with or without a larger quantity of glucose. The glucose caused virtually complete assimilation of 15N but had no effect on apparent assimilation of 14C. Thus, there was no relationship between 15N assimilation and 14C assimilation, suggesting that the C and N contained in organic N are processed separately by soil microbes. Inorganic N availability may have short-term effects on metabolism of C in organic N but long-lasting effects appear to be minimal

Salt flux into coastal river plumes: Dye studies in the Delaware and Hudson River outflows

The results of ten dye tracer experiments conducted in 2003–2006 to study the dispersion of the outflow of the Delaware and Hudson Rivers are presented. A fluorescent dye tracer was used to track the river plume and to measure directly the salt flux into the plume. A variety of flow regimes were encountered. During strong upwelling events, a salt flux of ∼3 ÷ 10–4 kg m s–1 at the leading edge of the plume implies a vertical diffusivity of Kz ∼ 3 × 10–4 m–2 s–1. Comparable salt flux was measured at the leading edge of a buoyancy-driven coastal current with Kz ∼ 6.3 × 10–4 m–2 s–1. For weaker wind events Kz was ≤10–4 m–2 s–1. Using a gradient Richardson number (Ri), these observations were replicated by a 1-D model of vertical salt flux to within a factor of 2. Upwelling events are the most efficient mechanism for dispersing the river plume water over the coastal shelf because the plume\u27s offshore displacement is combined with a horizontal diffusivity measured to be ∼150 m–2 s–1 over the two-day period of each experiment

Elucidating thermochemical pretreatment effectiveness of different particle-size switchgrass for cellulosic ethanol production

Effects of switchgrass particle sizes (\u3c0.25 mm, 0.5–1.0 mm, and 2.0–4.0 mm) on the effectiveness of H2SO4 and NaOH pretreatments were investigated. As particle size increased, glucan, xylan, and lignin contents in raw switchgrass augmented from 30.32% to 32.02%, 18.44% to 19.03%, and 14.78% to 15.33%, respectively. Glucan and xylan (58.54–60.94% and 18.55–20.01%) contents in NaOH pretreated switchgrass and their recoveries (91.95–94.69% and 47.91–52.31%) increased. The highest glucan content (55.76%) and recovery (79.72%) in H2SO4 pretreated switchgrass were reached by middle particle size. The lowest (59.39% for H2SO4 and 58.99% for NaOH) and highest (65.23% for H2SO4 and 66.15% for NaOH) CrI values were obtained from middle and small particle sizes, respectively. SEM images and FTIR spectra showed no visible variations in microstructures and chemical bonds among different particle sizes under the same pretreatment conditions. On the basis of pretreated switchgrass, the highest ethanol concentration and efficiency were reached by big particle size for H2SO4 pretreated (7.03 g/L and 49.28%) switchgrass, while they were achieved by small particle size for NaOH pretreated (11.68 g/L and 72.37%) switchgrass. The highest ethanol yield based on raw switchgrass was attained by big particle size for untreated (29.54%), middle particle size for H2SO4 pretreated (30.60%), and small particle size for NaOH pretreated (62.36%) switchgrass. These findings indicate that the optimal ethanol conversion performance is the result of the interaction between the pretreatment method and biomass particle size