Addressing the Tw in Challenges of Soil Degradation and Diminished Food Sovereignty across Urban-Rural Systems

Soil management, restoration, and conservation have long been central to all three dimensions of agroecology (science, practice, movement). For instance, early scientific articles in the field investigated the soil-building practices of traditional cultures, measured key soil parameters, and found long-term soil fertility to be a desired outcome of practitioners (Gliessman, Garcia, and Amador 1981; Altieri 1995). Practitioners of agroecology across the world emphasize the importance of soil to agroecology (Nyeleni 2015). Yet a number of recent developments in soil science have not been widely integrated into agroeco- logical research or practice, with implications for restoring ecosystem services. On the other hand, since soil science as a scientific discipline focuses mainly on biophysical understanding of soils and technical aspects of soil management, it is not well-poised to consider the motivations and knowledge of practitioners, or to motivate the action needed to change socio-political systems that constrain alternative futures for farmers. And both fields have much to gain from engaging more deeply with critical geography to address growing urbanization and the social inequities brought with it. In the following sections, we begin a series of conversations among these three disciplines, in which solutions from one is contextualized or problematized by the others. In doing so, we hope to foster deep, critical engagement with the social and ecological issues that span urban-rural landscapes.

Building Healthy Soils in Urbanized Landscapes

The idea of “soil health” has rapidly gained traction among researchers, practitioners, and even the general public as a means of conceptualizing soil as an emergent, living system and suggesting links between soil and human health (Doran and Zeiss 2000). Soil health focuses on the extent to which the dynamic properties of soil are managed for multiple ecosystem services, given inherent constraints of climate, parent material, and soil type (Moebius-Clune 2016). In this way, soil health is understood in relation to human intervention, and is made meaningful only when translated into practice (Doran 2002). The focus on multiple ecosystem services also emphasizes that soil can do more than just provide a medium for plant growth and provisioning food, emphasizing the role of soils in supporting, regulating, and cultural services as well (Kibblewhite, Ritz, and Swift 2008).

But urbanization significantly alters perceptions of and engagement with soil through pollution, displacement. and physical disconnection (Kim et al. 2014; Armstrong 2000; Brevik et al. 2019), placing soil management practices within the increasingly political context of urban land use (Cutts et al. 2017). The contested history of community farms and gardens in Sacramento, CA and changing perceptions of soil health, provide a stark example. In the 1950s, a number of working-class homes and businesses located near Sacramento’s capitol building were razed by the state government, but the site was never redeveloped (Cutts et al. 2016). By the 1970s, a robust, community-based garden serving over 100 families had taken root in those vacant lots, ultimately calling themselves the Ron Mandella Community Garden (Francis 1987). Over a protracted 30 year conflict with state and city governments, the issue of soil lead contamination and perceptions of the garden's soil health became central to the fate of the garden (Cutts et al. 2017). When proponents of the garden justified protecting the site because of its well-established soil health, state and city officials countered by planning to physically transport the topsoil to a new location. This led activists to decry the soil lead pollution at proposed alternative sites as prohibitive. Then, when high concentrations of lead were found at Mandella’s original location, the logic of contamination suddenly cut the other way, discrediting the claims that Mandella’s soil was healthy and worthy of cultivation (Cutts et al. 2017). Ultimately, the garden was razed. This demonstrates how perceptions of soil health—highly politicized and co-opted by stakeholders for distinct ends—is used to justify access and use of soil resources in urbanized areas.

This is a far cry from the “soil health” concept leveraged by rural farmers, soil scientists, and agronomists. Soils in cities are rarely viewed as provisioning food, fiber, or medicine, and therefore the soil health framework has not been as widely applied to urbanized landscapes as to agricultural soils in rural areas (Brevik et al. 2019). Perceiving soil as a living system, or connected to human and ecosystem

A volunteer harvests lettuce from the Oxford Tract in Berkeley

FIGURE 4.1 A volunteer harvests lettuce from the Oxford Tract in Berkeley. CA. where researchers and students established a model no-till farm, studying how small-scale agroecosystems can be managed to both improve soil health and address food insecurity

health, is in direct competition with urban development that sees land as a commodity to be bought, graded, and shaped (Cutts et al. 2017). Some notable examples of soil health analyses in urban areas exist in the literature, many of which develop a “soil quality” or soil health index to determine the most critical factors governing soil functioning in urbanized landscapes (Scharenbroch et al. 2005: Beniston et al. 2016; Tresch et al. 2018; Knight et al. 2013; Reeves et al. 2014). In applying an agroecological perspective, however, it is apparent that these studies do not capture the political, social, and cultural contexts that are necessary to sustain or enhance soil management in those urbanized landscapes.

Soil health is thus a useful framework for conceptualizing and assessing soils across urbanizing systems and for establishing benchmarks relevant to highly altered, politicized, and contested soils. By focusing on dynamic properties, soil health is also differentiated from soil quality, a concept that includes inherent soil properties in describing the suitability of soil for agricultural production or other uses. For instance, inherent properties (e.g. texture) of imported soils or soil blends often diverge strongly from locally-formed soils (Obrycki et al. 2017). This changes the absolute magnitude and array of soil-based ecosystem services that can be promoted from the filling and transport of soils, a common practice in the logic of urbanization that treats land as an exchangeable commodity. Soil health management that meaningfully addresses urbanization should try to promote holistic soil functioning while also considering the biophysical, social, and cultural constraints that occur in cities. As an example, a study in Berkeley, CA helps illustrate how concepts of soil health are problematized by these aspects of urbanization. Case Study: Connecting Soil Health and Hunger Relief on Contested Land

In 2017, an interdisciplinary team of agroecologists with expertise in entomology and soil, along w ith city planners and cooperative extension specialists at the University of California, Berkeley (UCB) set out to evaluate: 1) how urban agroecosystems can be designed to enhance ecological processes; and 2) whether urban food production can meaningfully address food insecurity (A. Siegner et al. 2018). This work included input from a constellation of small farms across the San Francisco Bay Area and other regions of Northern California, including two model no-till farms on land ow'ned by UCB: the Oxford Tract (1.2 acres) located in Berkeley, CA and the Gill Tract Community Farm (10 acres) located in Albany. CA.

Maximizing ecological processes in urban agroecosystems poses unique challenges regarding labor, land, capital, machinery, and amendments. By working with small urban and rural farmers across

California, researchers hoped to better understand how social and ecological contexts determined farmer’s success in building soil health. These farms were united by their use of no-till management systems and all experienced land and capital limitations of some kind. However the farms also spanned an urban- rural gradient that mapped onto socioeconomic and racial differences: urban farmers were predominantly Black. Indigenous, or РОС and operated non-profit or cooperative projects, while rural farmers were predominantly white with market-facing enterprises. At a symposium held on February 11, 2019 in Davis, California, practitioners from over 30 different farms and organizations discussed scientific, agronomic, economic, and cultural issues surrounding no-till farming for organic farmers with limited access to land and capital. At this symposium, the group helped outline the foundational principles included in “biointensive” no-till: 1) minimize soil disturbance, 2) maximize crop density in space and time, 3) maximize on-farm biodiversity above and belowground, 4) promote holistic management that increases biological activity, and 5) mitigate and adapt to climate change. These principles were shared widely amongst farmers but implemented in a variety of ways across California depending on their social context and site-specific needs and constraints. Crucially, biointensive no-till management requires little machinery, inputs, capital, or infrastructure, and can be implemented at both small and medium scales.

The research team at UCB implemented biointensive no-till principles on a model farm at the Oxford Tract, creating a factorially replicated and randomized block design to understand the impact of no-till management and cover cropping on key indicators of soil health. These indicators included soil carbon stocks and dynamics, water retention, biological activity and diversity, nutrient density and acquisition, and drought stress tolerance. After two years of diversified vegetable production and no-till management, the model farm was intensively sampled for these indicators in the summer of 2019. During that season, a model crop (Phaseohts vulgaris; black bean), grown as part of a polyculture, was subjected to simulated drought conditions and monitored over the growing season. The results demonstrated that the physical, chemical, and biological properties of soil ecosystems can shift dramatically in a short period of time under no-till management, much faster than the majority of the literature claims (Mitchell et al. 2017). First, no-till management dramatically increased soil moisture content under a drought scenario. Stem water potential, a proxy for plant drought stress, was also found to be lowest under no-till management and cover cropping, likely due in part to improvements in measured water retention and soil moisture. This has serious implications for urban agriculture facing drought conditions in California and high water costs due to residential rates (Pathak et al. 2018). Black bean yield was highest under no-till management and cover cropping, but showed no significant differences across treatments in nutrient acquisition or protein content. Still, high yields of a protein and calorie-rich food in the urban context demonstrates the capacity of urban food production to meaningfully contribute to nutrition. Plant performance and drought resilience showed no clear relationship with arbuscular mycorrhizal fungi (AMF) colonization of plant roots or with fungal community composition. Future research aims to resolve some of the intricacies of these plant-soil-microbe interactions. Management was also found to alter both the rate and location of soil enzymatic activity: biointensive no-till increased enzyme activity at all soil depths and shifted enzymatic activity to smaller particle fractions (clay particles, <20 pm). This has direct implications for the stability of soil carbon under no-till management (Cotrufo et al. 2013). Taken together, these measurements helped to capture the dynamic physical, chemical, and biological responses of soil ecosystems to a management system.

The study went beyond just evaluating soil biophysical properties, however. The research team also sought to understand whether urban farms meaningfully address food insecurity in the region. Through a series of interviews, mapping projects, surveys, and community partnerships, UCB researchers were able to track the movement of produce from the Oxford and Gill Tracts to dozens of organizations directly serving low-income residents (A. B. Siegner et al. 2020). This research is ongoing, but preliminary results demonstrate how informal networks, coalition building and cooperativism between organizations, anti-capitalist solidarity economies, and centralized distribution centers all help urban agriculture better address food insecurity. These findings are situated within a vital culture of urban agriculture in Oakland that draws inspiration from the city’s radical food justice programs and politics, including the free breakfast program hosted by the Black Panthers starting in 1969 (Curran and Gonzalez 2011).

Despite this history, UCB's agricultural research sites are heavily contested, both politically and culturally. The Gill Tract was the site of the Occupy the Farm (OTF) movement in 2012, a direct action mobilization to realize food sovereignty that stemmed from the broader Occupy movement of the previous year. In the late 2000s, the Gill Tract was slated to be developed into a parking lot. Whole Foods, senior living center, and baseball fields. OTF was a land occupation that opposed this development, establishing a community farming project at the Gill Tract and calling for anti-capitalist solidarity economies, land reform, and democratic or autonomous governance structures (Roman-Alcala 2018). The occupation was a threat to UCB, who ultimately sent in the University of California Police Department (UCPD) and arrested the occupiers. But a protracted battle between UCB and community organizers delayed the development and OTF was successful in establishing the Gill Tract Community Farm (Roman-Alcala 2018). The farm still operates today, growing 11-12,000 pounds of free produce a year for the community.

The Oxford Tract is the site of more recent controversy, as UCB’s Chancellor and Capital Strategies office have announced their decision to develop student housing on the site. This poses threats to the research, teaching, student organizing, and farm-to-food pantry programs that currently operate on the site (Treffinger and Jacobson 2018). It also poses threats to the rich ecosystem services and biodiversity of the site, where, for example, 84 distinct native bee species were found over a two year period (Frankie et al. 2009). Two of the primary justifications made by students and activists for maintaining these sites for agricultural use are the fertile, alluvial soils (Treffinger and Jacobson 2018) and contribution of student farming projects to campus food security through regular donations to the Berkeley Student Food Pantry. These struggles situate concepts of soil health within a complex web of social, cultural, and ecological forces, and complicate how soil health is interpreted in urbanized landscapes.

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