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Aluminum
Published in Brian D. Fath, Sven E. Jørgensen, Megan Cole, Managing Global Resources and Universal Processes, 2020
Bernhard Wehr Johannes, Cardell Blamey Frederick Paxton, Martin Kopittke Peter, William Menzies Neal
Aluminum has no known biological benefit to living organisms and is toxic in micromolar concentrations. Since solubility of Al is minimal at circumneutral pH, alleviation of Al toxicity can be achieved by pH adjustment. Complexation of Al by organic acids and humic substances also lowers biotoxicity of Al. While Al toxicity in soil can be easily overcome by incorporating lime into the soil by tilling, new management strategies need to be developed to counteract soil acidification and consequent Al toxicity in zero-till farming systems. The decrease in atmospheric acid inputs (acid rain) over the last two decades has resulted in lower Al solubility and less Al damage to aquatic ecosystems. Uptake of Al in humans through foodstuff and water poses an uncertain risk, but pollution with nano-particulate Al may result in human health problems. The effect of nano-sized Al particles on the functioning of soil and water ecosystems, as well as human health, needs more research.
Chemistry and Agriculture: Helping to Feed the World
Published in Richard J. Sundberg, The Chemical Century, 2017
Various agricultural practices have the potential to reduce these emissions. No-till farming decreases energy use and favors carbon retention in the soil. Grasslands sequester CO2, and under optimal management including fertilization, the extent of carbon capture can increase. Restoration of degraded land, including improved water management, can also increase carbon retention. Precision nitrogen fertilization can decrease N2O emission and fertilizer runoff. Possible means of reducing methane generation include capture from waste. It may also be possible to reduce methane generation directly from animals by feeding practices, or biochemical (drug) manipulation. The largest factor will probably be the extent of biomass conversion for energy. Biomass conversion reduces net generation of CO2. The balancing factor here, however, is the competing use of land to generate food supplies (see Section 2.2.3).
Food
Published in John C. Ayers, Sustainability, 2017
Herbicide resistant GMO crops that can tolerate the herbicide glyphosate (tradename Roundup) are now widely used. Normally farmers have to eliminate weeds between plantings by plowing (tilling) the soil, a process that adds large amounts of carbon dioxide to the atmosphere in two ways: by exposing soil carbon to the atmosphere so that it can be converted to carbon dioxide through bacteria-mediated oxidation, and through burning fossil fuels to provide the energy for tilling. Farmers that use “Roundup-ready” crops can use the more environmentally friendly practice of no-till farming, a sustainable alternative to plowing that uses less fossil fuel energy than conventional tilling and decreases soil erosion. Rather than removing crop residues at the end of the fall harvest, farmers leave it in place over the winter to protect the soil from erosion and to gradually decompose and release nutrients to the soil. In the spring farmers use a special machine to cut slits in the residue and insert GMO seeds in the slits. When the seedlings sprout they spray the entire field with glyphosate to kill all of the weeds. Glyphosate rapidly degrades in the environment, so it is less harmful to ecosystems than most herbicides. The crop residue acts like a mulch, holding in moisture and therefore decreasing water needs (Collin and Collin 2010). No-till farming also promotes retention of soil carbon. Studies show that using glyphosate-resistant crops results in small yield increases without reducing plant diversity, although integrated pest management strategies are needed to prevent the development of glyphosate-resistance in weeds (National Academy of Sciences 2016). To date the evidence indicates that use of GMO crops with insect and herbicide resistance can increase food security and decrease the environmental impacts of agriculture.
Multi-site watershed model calibration for evaluating best management practice effectiveness in reducing fecal pollution
Published in Human and Ecological Risk Assessment: An International Journal, 2020
J. Sebastian Hernandez-Suarez, Sean A. Woznicki, A. Pouyan Nejadhashemi
Multiple BMPs as defined by stakeholders, were implemented in SWAT (Supporting Information (SI) Section A1 and Tables A1 through A10 in the Appendices): conservation-till farming, no-till farming, rye cover crop, red clover cover crop, edge-of-field filter strips (10 m and 30 m width), nutrient management (20% and 50% reduction of fertilizer application), and reduction of E. coli load from failing septic systems/wildlife (20% reduction, 40% reduction, 60% reduction, 80% reduction, and 100% reduction). All BMPs (except septic systems/wildlife) were implemented on agricultural HRUs in priority order based on the three land-based load reduction scenarios. The failing septic systems/wildlife E. coli reduction BMP was only implemented under the load reduction scenario addressing input data uncertainty regarding the E. coli sources. Two livestock operations were identified in the EBCC watershed. One site was not located near a stream, while livestock at the second site previously had access to the stream, but fencing was constructed to limit access following the development of the original E. coli TMDL in 2006. Therefore, no additional BMP to address livestock access was modeled.