Stephen R. Gliessman

Integrating social, environmental, and economic issues in sustainable agriculture

In the past several years, researchers, educators, policymakers, and activists have initiated sustainable agriculture programs and efforts the world over. This development has sometimes been accompanied by a sense that it is time to stop discussing sustainability at a conceptual level and get on with the work of making agriculture sustainable. Our perspective is that it is critical to pursue a comprehensive definition of sustainability in order to set sustainable agriculture priorities and ensure that sustainable agriculture takes a path that does not reproduce problems of conventional agriculture. In this paper we briefly review some popular definitions of sustainable agriculture and find that their focus is primarily on farm-level resource conservation and profitability as the main components of sustainability. Others have challenged this approach for either not examining the social aspects of sustainability or for containing an implicit assumption that working on the environmental, production, and microeconomic aspects of sustainability will automatically take care of its social aspects. We propose an expanded conceptualization of sustainability—one that focuses on the entire food and agriculture system at a global level and includes not only environmental soundness and economic viability, but social equity as well. In this perspective, issues such as poverty and hunger are as central to achieving agricultural sustainability as those of soil erosion and adequate farm returns.

Agroecosystem sustainability : developing practical strategies

INCREASING SUSTAINABILITY The Ecological Foundations for Sustainability, S. Gliessman Increasing Sustainability in Mediterranean Cropping Systems with Self-Reseeding Annual Legumes, F. Caporali and E. Campiglia Manipulating Plant Biodiversity to Enhance Biological Control of Insect Pests: A Case Study of a Northern California Organic Vineyard, C. Nicholls and M. Altieri An Assessment of Tropical Homegardens as Examples of Sustainable Local Agroforestry Systems, V. E. Mendez Improving Agroecosystem Sustainability Using Organic (Plant-Based) Mulch, M. Rosemeyer ASSESSING SUSTAINABILITY Nitrogen and the Sustainable Village, E.C. Ellis, R. G. Li, L.Z. Yang, and X. Cheng Nematode Communities as Ecological Indicators of Agroecosystem Health, D.A. Nehr Field-Scale Nutrient Cycling and Sustainability: Comparing Natural and Agricultural Ecosystems, J. Muramoto, E.C. Ellis, Z. Li, R.M. Machado, and S. Gliessman COMBINING SOCIAL AND ECOLOGICAL INDICATORS OF SUSTAINABILITY Assessing Agricultural Sustainability Using the Six-Pillar Model: Iran as a Case Study, A. Farshad and J. A. Zinck Coevolutionary Agroecology: A Policy- Oriented Analysis of Socioenvironmental Dynamics, with Special Reference to Forest Margins in North Lampung, Indonesia, R. Gauthier and G. Woodgate Operationalizing the Concept of Sustainability in Agriculture: Characterizing Agroecosystems on a Multi-Criteria, Multiple-Scale Performance Space, M. Giampietro and G. Pastore

The creation of an integrated sustainability curriculum and student praxis projects

Purpose – The purpose of this paper is to share the content and early results from an interdisciplinary sustainability curriculum that integrates theory and practice (praxis). The curriculum links new topical courses concerning renewable energy, food, water, engineering and social change with specialized labs that enhance technological and social‐institutional sustainability literacy and build team‐based project collaboration skills.Design/methodology/approach – In responses to dynamic interest emerging from university students and society, scholars from Environmental Studies, Engineering, Sociology, Education and Politics Departments united to create this curriculum. New courses and labs were designed and pre‐existing courses were “radically retrofitted” and more tightly integrated through co‐instruction and content. The co‐authors discuss the background and collaborative processes that led to the emergence of this curriculum and describe the pedagogy and results associated with the student projects.Find...

Allelopathic interactions in crop-weed mixtures : Applications for weed management.

A very important component of the aggressive nature of weeds is allelopathic interference, the full potential of which is just being realized in the management of agroecosystems. Research results are presented which demonstrate the allelopathic interactions involved in a wide range of cropweed combinations occurring in a great variety of habitats. This includes crops planted in weed control, crops with allelopathic potential, and noncrop plants of beneficial use for weed control as a result of allelopathic interference. Allelopathy can play a beneficial role in multiple cropping systems, crop rotations, and cover cropping. The potential role for allelopathic interactions in the design of biological weed control is proposed.

Agroecology in the tropics: Achieving a balance between land use and preservation

Agroecology is the application of ecological concepts and principles to the design and management of sustainable agricultural systems. An agroecological approach to agriculture has special importance in the humid tropics where agricultural development and the preservation of tropical forests are most often in direct conflict. It is proposed that a more sustainable approach to development is needed, where agroecosystems depend on low external inputs, function more on the use of locally available and renewable resources, have benign impacts on the environment, and are based on the knowledge and culture of the local inhabitants. Examples of traditional agroecosystem management in Mesoamerica that can provide this basis are presented. The preservation of both biological and cultural diversity are integral to the long-term sustainable management of natural resources in the tropics.

Effects of plant diversity on the density and herbivory of the flea beetle, Phyllotreta cruciferae Goeze, in California collard (Brassica oleracea) cropping systems

Abstract Populations of the flea beetle, Phyllotreta cruciferae Goeze (Coleoptera:Chrysomelidae), were greater in weed-free collards than in collard monocultures and polycultures (intercropped with beans) left weedy for 2 or 4 weeks after transplanting or for the entire season. Flea beetle densities and amount of leaf damage per individual collard plant were significantly lower in the plots with crucifer weeds (mainly Brassica campestris L.), possibly because the beetles preferred to feed and/or concentrate on this plant rather than on collards.

Crop Interactions in Broccoli Intercropping

ABSTRACT The research goals were to evaluate crop suitability to intercropping systems, to evaluate a population density limit to successful intercropping and to study the main factors responsible for crop performance when intercropped. Three experiments were carried out during 1995 and 1996 by intercropping broccoli either with contrast crops (pea, beans, potato or oats) or with similar crops (cauliflower or cabbage) in additive and substitutive designs at different intercropping rates. The overall intercrop characteristics as leaf area index, soil coverage and biomass yield were not related to a higher yield, and similar results were due to different factors. Land Equivalent Ratios (LER) similar to 1.0 were due either to a high and constant Relative Yield (RY) of the main crop associated with low RY of the secondary crop, or to trade-off between the RY of both associated crops. Similarly, a LER of 1.34 resulted from a reasonable performance of the dominated crop (beans) in the second experiment at the 50% additive design, whereas in the third experiment there was no dominating crop in the broccoli-potato intercropping but the LER reached 1.27. The mechanisms involved in the overyielding were the bean canopy plasticity and its temporal deployment asynchrony when compared with broccoli, allowing reduction of the competition for light, and the crop development temporal asynchrony between broccoli and potato, reducing the competition for production factors.

Integrating Agroecological Processes into Cropping Systems Research

Summary Agroecology is defined as the application of ecological concepts and principles to the design and management of sustainable agroecosystems. By viewing cropping systems as agroecosystems, an understanding of the value of the emergent qualities of systems can become a guiding element in research design. A framework for applying this approach in cropping systems research in proposed. A protocol for researching the conversion to sustainable agriculture involves three levels of investigation. The first focuses on improving the efficiency of conventional farming inputs and practices in ways that reduce both their amounts and the environmental impacts of their use. The second focuses on substituting conventional inputs and practices with alternatives that meet broader environmental standards, such as certified organic. Since the problems addressed at these two levels continue to present themselves, a third level is proposed whereby the agroecosystem is redesigned so as to operate on the basis of a new set of ecological processes. At this third level, the emergent qualities of the system itself help prevent problems. Such an approach promotes the conversion to sustainability.

Agroecosystem responses to organic and conventional management practices

Abstract The stability and resilience of two very similar soil ecosystems were challenged over an extended time by organic and conventional management systems. The responses were compared against a native soil ecosystem by following carbon, nitrogen and phosphorus balances through the biological, geological, and chemical sub-systems. The types and amounts of carbon inputs did not predict the resulting system contents or properties. Nitrogen and phosphorus retained in the systems were related to, but not proportional to, inputs. Carbon, nitrogen and phosphorus moved through the agroecosystems and excesses were exported to maintain stasis in the component sub-systems. A flow diagram was proposed to describe the stabilizing responses in these systems. The unique properties of each agroecosystem must be considered when developing sustainable management practices.

Colonization of Strawberry Roots by VA Mycorrhizal Fungi in Agroecosystems under Conventional and Transitional Organic Management

ABSTRACT Mycorrhizal colonization of strawberry roots was studied for two agricultural management systems on the California central coast, one conventional and one in transition to organic. Low levels of VAM colonization early in the first year of the experiment may be the result of past management practices, which included conventional production of a non-mycorrhizal crop with high levels of phosphorus inputs. In the second year colonization levels were higher in the transitional organic plots. Annual use of a fumigant and a fungicide in the conventional plots was implicated with depleting the VAM inoculum reservoir and maintaining low colonization levels. Inoculation of organically managed plots with Glomus intraradices at the second planting did not change colonization levels. Soil analyses showed that available soil phosphorus levels remained high (range 62 to 101 ppm) in both treatments throughout the study. In both years colonization increased during the spring and summer harvest season, and it is h...