Conceptualizing Agricultural Sustainability: Valuing Ecosystem Services in the Assessment of Cover Crops
- Crézé, Cynthia Marie
- Advisor(s): Horwath, William R.
The conceptualization of agricultural sustainability has become increasingly complex. Sustainable food production must account for multiple societal imperatives, including meeting the nutritional needs of a growing population, adapting to climate change and mitigating its effects as well as preserving biodiversity in support of natural ecosystems. Ecosystem services refer to the multiple benefits, which humanity obtain from ecosystems. To address challenges facing agriculture, sustainable practices have been developed through scientific research. My dissertation explores the case of cover cropping for perennial systems, as one such science-based practice developed to support agricultural sustainability. Cover crops are plant species that are seeded in addition to the main food crop in agro-ecosystems. Prior literature demonstrates that cover crops can improve nutrient cycling and other soil properties, and can also bring other services, such as refuge for beneficial insects and the suppression of weed species. Despite considerable scientific evidence, there remains low adoption of cover crops in global agriculture. I believe that major gaps between the establishment of scientific evidence and the actual uptake of sustainable practices hinders progress. In the case of cover crops, this lag may in part be due to remaining data gaps hampering the successful establishment and use of the practice. However, I suggest that lack of adoption is due less to large gaps in knowledge, and more a result of conflicting ecosystem service valuation systems among stakeholders. In Chapter 1, I present the results of a farmers’ survey specific to almond production in California. The purpose of this survey was to better understand the factors that affect the decision to use cover crops for almond farmers. Results indicate that while most farmers recognize the many ecosystem services of the practice, concerns over water use and economic costs of the practice can dissuade farmers from adopting the practice. However, the perception of cover crop outcomes was not uniform among farmers. Our results reveal distinct systems of ecosystem service valuation, determined by farm size and regions of California (Sacramento Valley, North San Joaquin Valley and South San Joaquin Valley). In Chapter 2, I conducted a systematic review of cover crop literature to explore scientific rationales for cover cropping. Our analysis of researchers’ knowledge pathways indicates two distinct systems in the valuation of cover crop services: a biological management approach, which considers ecological conservation as inherently valuable, irrespective of immediate profitability, and a nutrient management approach, which prioritizes resource conservation for sustainable crop production. Our results highlight different conceptualizations of agricultural sustainability within literature. Chapter 3 explores how cover crop ecosystem service frameworks vary across commodity types. Our analysis reveals different systems of ecosystem service valuation specific to commodity types and their diverse approaches to agricultural sustainability. Certain commodities (i.e., olive and vineyard systems) focused on cover crop outcomes specific to water use services whereas others prioritized biological control services. These findings emphasize the need to reflect stakeholder priorities in the design of ecosystem service frameworks, to inform their decision to cover crop. This work supports the development of data-based decision-making systems, which reflect diverse approaches to agricultural sustainability.