Key practices such as no-till farming, optimal use of biomass , groundwater recharge, and substitution of chemical inputs for natural processes require further place-based research in order to develop and disseminate “best practices” for large scale operations through farmer-to-farmer and extension networks.Inspired by Dr. Timothy Wise’s book Eating Tomorrow: Agribusiness, Family Farmers, and the Battle for the Future of Food and Dr. Molly Anderson’s recent paper “The importance of vision in food system transformation,” I aim to contribute to building and implementing a shared vision for tomorrow’s food system, one that is climate mitigating, ecologically restorative, land based, and empowering of small farmers and historically marginalized groups in food system politics. A vision “is a beginning for transformation, but it requires policy that enables it to be enacted, ideally through democratic processes. The vision, buttressed by policy and democratic governance, is what determines where people are able to buy food, how much they pay, whether farmers earn decent incomes, and whether the food is healthy” . Lopez Island food system actors have made incremental progress articulating a vision since 1989, starting with the mission statement of the Lopez Community Land Trust. The East Bay region of the San Francisco Bay Area is building a vision for increasing food security via urban agriculture through the work of Food Policy Councils in Berkeley, Richmond, and Oakland. Small farms in both Washington and California are starting to put forth a vision for how regenerative agriculture and farm-based education can aid in the battle against climate change. Bringing these visions together under the polycentric governance model, hydroponic shelf system policy recommendations must be targeted at the appropriate level: county governance for zoning code updates and land use designations, state governance for climate and environmental education standards and funding, and national level policy to revamp the Farm Bill into an incentive package for smaller-scale, regenerative, relocalized agricultural operations.
Building off of the body of research presented in this dissertation, one of my future goals is to establish a Climate Farm School, where young people can come to a demonstration farm and deepen their understanding of the climate crisis while engaging in climate solutions through producing food. The purpose would be threefold: 1) establish a demonstration farm that models climate friendly agricultural practices while producing and distributing food, 2) educate young people and aspiring farmers how to implement and improve climate friendly practices, and 3) engage with local universities in research projects to explore and scale agricultural climate change mitigation/adaptation. My vision is that this farm school could arise through partnership with an existing farm, or through the right opportunity of land acquisition and fundraising.While I seek to engage first with the youth education sector, I can imagine a parallel “Climate Farm School” for policymakers to better understand and connect with climate-friendly farming operations in their areas of jurisdiction to inform and direct their policy proposals. Bringing young people and policymakers into the sustainable food system transition process is a critical step for food system researchers to take in order to realize positive change. Dendritic wetland designs, which consist of a sinuous network of water-filled channels and small, vegetated uplands, can help reduce water turbulence associated with high winds .Vegetative cover has been shown to decrease sediment re-suspension. For example, Braskerud found that an increase in vegetative cover from less than 20 percent up to 50 percent reduced the rate of sediment re-suspension from 40 percent down to near zero. Wetland depth may also have an indirect effect on sediment retention.
The water should be deep enough to mitigate the effect of wind velocity on the underlying soil surface, but if the water is too deep, vegetation will not be able to establish and a significant increase in re-suspension of sediment will result. Water depths between 10 and 20 inches optimize conditions for plant establishment, decreased water velocity, well-anchored soil, and a short distance for particles to fall before they can settle . An excess of vegetation can significantly reduce a wetland’s capacity to retain E. coli. Maximum removal of E. coli occurs under high solar radiation and high temperature conditions , and vegetation provides shading that can greatly reduce both UV radiation and water temperatures. While vegetation can provide favorable attachment sites for E. coli, a dense foliage canopy can hinder the free exchange of oxygen between the wetland and the atmosphere. This vegetation induced barrier to free exchange of oxygen limits dissolved oxygen levels, and that in turn reduces predaceous zooplankton, further decreasing removal of microbial pathogens from the wetland environment . Vegetation plays an important role in filtering contaminants in wetlands. The plants’ uptake of pollutants, including metals and nutrients, is an important mechanism, but is not really considered a removal mechanism unless the vegetation is harvested and physically removed from the wetland. Wetland vegetation also increases the surface area of the substrate for microbial attachment and the biofilm communities that are responsible for many contaminant transformation processes. Shading from vegetation also helps reduce algae growth. However, certain types of vegetation can attract wildlife such as migrating waterfowl, which may then become a source of additional pathogens. Vegetation that serves as a food source or as roosting or nesting habitat for waterfowl may need to be reduced in some settings. Among other important considerations for vegetation coverage in wetlands, one must include total biomass and depth features.
Vegetation should provide enough biomass for nutrient uptake and adsorptive surface area purposes, but must also be managed to allow sufficient light penetration to enable natural photo degradative processes and prevent accumulation of excessive plant residues, which would prevent the export of dissolved organic carbon. One way to promote this balance is to create areas of deeper water intermixed with the shallower areas. Plants will establish more readily in the shallow areas and less so where the water is deeper. In an agricultural setting, it may be hard to establish plantings of native species within wetlands due to the large seed bank of exotic species that may be present in input waters . You can also manage the type and amount of vegetation by manipulating the timing and duration of periods of standing water in the system. In extreme instances, you can actually harvest excess biomass.In addition to managing vegetation and water depth to maximize sedimentation and pathogen photo degradation, cannabis drying racks commercial growers can also manipulate hydrology to maximize the removal of microbial pollutants in wetlands. The importance of hydrologic residence time is apparent when you recognize that a longer HRT increases the exposure of bacteria to any removal processes such as sedimentation, adsorption, predation, impact of toxins from microorganisms or plants, and degradation by UV radiation . E. coli concentrations have been shown to increase in runoff from irrigated pastureland when the volume of runoff is increased . High runoff rates increase the mobility of contaminants from fields and decrease the HRT within the wetland, thus reducing the opportunity for filtering pathogens. Despite variations in several characteristics among the four flow-through wetlands in the case study described earlier, HRT wasa consistently good predictor of E. coli removal efficiency. Mean removal efficiency was 69, 79, 82, and 95 percent for wetlands having mean HRTs of 0.9, 1.6, 2.5, and 11.6 days, respectively . Remarkably, an HRT of less than a day can allow for considerable E. coli retention , which means that a relatively small wetland area can treat runoff from a relatively large agricultural area. The relationship between removal and HRT was not so clear for enterococci . In this case, W-1, with an HRT of 2.5 days, demonstrated a lower removal rate than W-2 or W-3, which had HRTs of 0.9 and 1.6 days, respectively . As discussed above, there are many parameters that can influence the environmental fate of pathogens in wetlands, including vegetation density, design, age, size, contributing area, and depth. A number of these wetland characteristics can doubtless be altered to increase bacteria removal efficiency. The efficiency with which contaminants can be reduced in agricultural water as it passes through a wetland is largely dependent on the extent to which water is evenly distributed across the wetland area. A wetland’s retention capacity is diminished if its design results in stagnant zones that either reduce the effective treatment area or short-circuit longer flow paths, decreasing the HRT. Efficient wetlands come in a variety of shapes and sizes.
A wetland should be wide enough to allow sufficient trapping of sediment and other particulate materials and long enough to permit sufficient residence time for nutrient removal. Most researchers agree that the surface area of a wetland should be as large as possible in order to maximize its HRT and storage capacity. The even dispersion of water across the wetland, termed hydraulic efficiency, is largely defined by the wetland’s dimensions and the relative locations of input and output channels. High hydraulic efficiency maximizes the removal of contaminants. Designs with good hydraulic efficiency have a shape that facilitates complete mixing throughout the wetland without the persistence of stagnant zones, or may incorporate barriers that achieve the same effects . All designs with good hydraulic efficiency have their input and output channels positioned on opposite ends of the wetland.The sediment trap is an important design feature in settings where the input water has a high level of suspended solids . Sediment traps are essentially small swales or ponds positioned between the source of the agricultural water and the main wetland to promote the settling of coarse particles before the water is distributed across the wetland. Sediment traps should be located in easily accessible areas where sediment can conveniently be removed on a regular basis. Incorporation of sediment traps in your design will decrease the amount of sedimentation within the wetland, lengthening the time you can go between dredgings. They also prevent the burial of germinating seedlings in the wetland and help limit channelization and short circuiting of flow paths.The amount of microbial pollutants in wetland soils is significantly higher than in the standing water. Bacteria survive longer in soil than in water . Fecal coliforms can persist in sediments for as long as 6 weeks , so the degree to which sediments are deposited in a wetland has a significant effect on the degree to which bacteria are exported in effluent waters, post-wetland. The survival time for pathogens varies widely in agricultural settings, probably as a result of local differences in environmental conditions . If conditions are conducive to pathogen survival, any of a number of wetland conditions that cause the re-suspension and entrainment of sediment—e.g., high water flow pulses into wetlands, wave action, or channelization—may lead to the release of waters that contain microbial pollutants. If you manage wetlands to allow for alternating episodes of flooding and drying, you may be able to decrease the survival of microbes in the wetland soil. In addition to desiccation associated with episodes of dry wetland soil, fluctuations in wetted surface area and depth can facilitate a diversity of biological and bio-geochemical conditions that optimize wetland function and minimize the duration of pathogen survival .There are two general options to reduce non-point source pollution from agriculture: on-site farm management practices that control the pollution source or limit the application of excess materials and their subsequent loss from farmlands, and off-site practices that intercept non-point source pollutants before they reach downstream waters. Wetlands can be used within a farm scape as either an on-site farm practice or an off-site tool, where downstream flood plains are converted to wetlands to mitigate pollution at the watershed scale. In settings where the attraction of wildlife is of concern, you may want to consider placing the wetland off-site, but at a place where it will intercept the runoff before it enters a natural water body. This may also require re-routing of the agricultural runoff into an off-site wetland.Johne’s disease is a chronic, infectious gastrointestinal disease of domestic and wild ruminants , caused by Mycobacterium avium subsp. paratuberculosis . Johne’s disease is a global disease, which was first observed in dairy cows in 1895. Environmental viability studies found that MAP can survive for 8 months in feces at ambient conditions and for 19 months in water at 38 degrees of centigrade. MAP remains viable in a desiccated state for up to 47 months.