Crop diversification would improve the sustainability of Western agricultural production systems, yet few farmers have adopted this approach. This chapter presents an economic analysis of the main lock-in effects explaining why cropping diversity has not become widespread. Technological lock-in has resulted from the coevolution of crop systems (based on the post-WWII agrochemical paradigm), public policies, and market dynamics that promote major crops such as cereals. This chapter explains how interrelated factors have favored increasing returns to adoption for cereals to the detriment of minor crops. The evolutionary economics approach used here identifies the main economic mechanisms that reinforce the choice of an initial production pathway. Today with the development of the bio-economy, we also examine whether new technological pathways in the agro-food sector may be able to reverse this lock-in.

A major challenge for agriculture in the early years of the 21st century is to develop cropping systems better able to cope with continuing climate change. These new systems must also be more sustainable and so must have fewer negative environmental effects. An element of such new systems could be the introduction of greater genetic diversity in our crops. Diversity can be viewed at different levels: genetic diversity, species diversity, and functional diversity. These will likely interact synergistically to increase the benefits gained beyond a simple additive function. Various examples will be given to illustrate how diversity within and among species may provide increased stability of biomass production and improved ecosystem services. The introduction of greater diversity to agroecosystems appears to be a promising way in which production systems may better adapt to climate change. It is also important we work to combine knowledge from a number of different research fields to design optimal mixtures of species and genotypes and improved ecosystem services.

Specialization of agricultural operations and commodities in many developed countries of the world during the last half century has led to large production gains, but often at the expense of environmental quality and socioeconomic disruption. Soil organic C is a key indicator of soil quality that is low with contemporary clean-cultivated specialized crop production practices and high when farms are managed with conservation tillage, cover crops, manure application, and diverse rotations, especially multiyear pasture-crop rotations. Our thesis is that integrating pastures and crops with other ecologically based practices leads to dramatic improvement in soil organic C and N contents and associated soil quality properties. Therefore, long-term fertility would be restored and environmental quality could be significantly improved to meet the challenges for greater quantity and quality of food production, sustenance of human health, maintenance of wildlife diversity, and balancing our human footprint with nature's capacity to serve our needs.

This chapter examines payment for unmarketed agroecosystem services as a means to promote agricultural diversity as well as payment for agricultural diversity as a way to increase the supply of wanted unmarketed agroecosystem services. The importance of treating agricultural diversity as a multidimensional concept is emphasized, and several of its dimensions are identified. After assessing generally policies for paying farmers for the supply of unmarketed agroecosystem services, particular attention is given to payments for on-farm product diversity as a means of sustaining or increasing the supply of desired unmarketed agroecosystem services. The importance of this diversification being integrated to achieve this end is stressed. Economic theory (despite its limitations) is shown to be helpful in identifying issues that need to be addressed when considering policies for paying farmers for their supply of agroecosystem services, for example, the importance of distinguishing the allocative and income distribution effects of such policies. The analysis of these matters is facilitated by the introduction of a simple social cost-benefit inequality and a specific economic model. The importance of taking account of public administration costs and legal barriers and their efficiency aspects when assessing the costs and benefits of agricultural policies is stressed because these aspects are frequently overlooked. Other relevant aspects of agricultural diversity, such as regional diversity, are also briefly examined. An alternative to paying farmers for the supply of wanted agroecosystem services is to penalize them for not doing so. This is examined. The prospect of greater agricultural diversity resulting in the short term in reduced supply of agricultural products (and an increase in their real prices) but a more sustainable supply of these products in the long term is raised.

This chapter discusses biophysical processes that explain the ability of silvoarable agroforestry systems to maintain agricultural yields while providing a range of ecosystem services. Silvoarable systems are very flexible, and many management practices can be used within them by farmers to sustain crop yields for as long as possible. These include the choice of tree and crop species, tree row orientation, tree row spacing, tree-thinning regimes, tree-pruning intensity, hedging of canopies, soil cultivation methods, and cover cropping. Tree roots do compete with crops, but they can also provide a “safety net” under crops to intercept nutrients and form symbioses with N-fixing or mycorrhizal organisms. Trees share light, water, and nutrients with crops, but competition can be minimized by ensuring increased resource use efficiency of the whole system. Trees increase the water-holding capacity of agricultural soils and contribute to the reduction and management of floodwaters. They influence climate at micro, meso, and macro scales and provide opportunities for climate change mitigation and adaption. At some silvoarable spacings, the arable crops will have to be replaced for the latter part of the tree rotation with pasture. These silvoarable systems then become silvopastoral (or agro-silvi-pastoral) in nature, and they are best suited to areas where mixed farming exists or can be reintroduced. The chapter's emphasis is primarily on temperate regions.

Organic agriculture is a system that aims to primarily use ecologic processes rather than external inputs to manage crops and livestock. Diversity is a key component of natural ecosystems and organic agriculture often includes the use of diversity as a management paradigm, as well as the stated goal to enhance diversity. But how does organic agriculture contribute to diversification in practice? And what are the potentials and limits of organic agriculture to enhance the diversity of the food production system? In this chapter, we will examine the evidence for implementation of diversification practices by organic farmers, as well for the diversification outcomes of organic agriculture. We will then conclude with a discussion and outlook on how organic agriculture can enhance the diversification of agroecosystems and the food system in general. On the one hand, large-scale economic drivers today typically favor the homogenization of food production systems, and organic agriculture—being a production system that is embedded in the existing food system—is thus faced with limits in its ability to foster diversification at the system level. On the other hand, multiple drivers, including climate change but also the increased importance of consumers in the food system, may alter the dominant socioeconomic drivers and may favor more resilient organic or organic-like production systems in the future. Organic agriculture may thus provide important contributions for a trajectory for moving toward more diversified food production, not only through diversification occurring within organic systems, but also by providing important lessons on diversified agricultural systems for conventional agriculture.

Many negative impacts on our environment and us are partly attributable to contemporary simplified, intensive agriculture, which frequently and problematically functions within national economic systems where social and environmental effects are not reflected in market values. Specialization of farms and farming regions have increased many environmental problems including greater reductions in air and water quality, less availability of water, more soil degradation, and more biodiversity losses. Greater negative effects on our environment are probably due to interlinkages among specialization, intensification, and enlargement of farms driven by industrialization and globalization of markets and may have been exacerbated by public policies such as Common Agriculture Policy in the European Union and national farm legislation the United States such as the federal crop insurance program. This approach to farming has also created concerns about food quality and human health. Potential negative effects on people include unhealthful working conditions in concentrated animal feeding operations, excessive exposure to pesticides, development of antibiotic-resistant bacteria, increasing exposure to steroid hormones associated with exogenous steroid growth promoters for livestock, increasing the risk of pandemic avian and swine influenza, increasing exposure to excessive levels of nitrates in drinking water, decreasing micronutrient availability in foods, as well as reduced availability of affordable healthful foods such as fruits and vegetables, and increasing stress on farming families.

The homogenization of agroecosystems through the loss of genetic diversity between and within crops, increased dependency on fewer crop protection products, and loss of seminatural features such as field boundaries threatens the sustainability of current crop protection strategies. The loss of crop diversity has selected for a narrow range of weed, pathogen, and pest species adapted to the small number of major crops currently being grown on a large scale. This, together with legislative restrictions on pesticide availability, has led to overreliance on a few chemical active ingredients, creating strong selection pressure for the evolution of pesticide resistance that is now a major agronomic issue in intensive agricultural systems. Examples include glyphosate-resistant palmer amaranth in US GM herbicide-tolerant crops, herbicide-resistant black-grass in NW Europe, triazole-resistant Septoria in UK wheat, and European populations of cabbage stem flea beetle in oilseed rape that are no longer controlled by synthetic pyrethroids. In parallel with the evolution of resistance, the increased use of pesticides and loss of noncropped habitats have also depleted populations of the natural enemies of crop pests or predators of weed seeds that we rely on to regulate outbreaks of pests, pathogens, or weeds. As a consequence, when the efficacy of the chemistry begins to decrease, we can no longer rely on predator-prey feedback dynamics that would ordinarily regulate the system. In this chapter, using examples and data from the literature and recent projects, we will demonstrate the necessity for increased diversity of crops, management, and landscapes as a framework for future, sustainable crop protection strategies.

While global demand for food increases, agricultural expansion faces more stringent environmental preservation demands and sustainability laws aimed to prevent deforestation (Nascente and Crusciol, 2012). Integrated crop-livestock systems (ICLS) are diversified agroecosystems that can contribute to sustainable intensification, increasing food production while maintaining or improving environmental quality and preserving natural biodiversity. A conceptual representation of ICLS can be drawn from the description of how crop and livestock activities interact. From a field- to territorial-level scale (e.g., landscape, watershed, or region), crop and livestock production can be structurally independent or interact in time and space dimensions (Moraine et al., 2016). ICLS are designed to achieve synergy and emergent properties resulting from the spatial and temporal interactions among the components soil, plant, animal, and atmosphere (Moraes et al., 2014a,b).

Agricultural specialization is a complex multidimensional process, with multiple drivers and consequences. In this chapter specialization—focusing largely on an “Eastern European/North American” perspective—is discussed in the context of the related notions of agricultural intensification and agricultural concentration. The primary drivers of agroecosystem specialization, including mechanization, economies of size and scale, technological innovations, comparative advantage, market forces and “productionist” agricultural policies are described. Next, agricultural specialization is related to farms and farmland characteristics, notions of efficiency, and the geographic scale of specialization. The relations between multiscalar specialization and multiscalar ecologic simplification are outlined. Finally the consequences of specialization are assessed in terms of their potential ecologic and economic impacts on four key agroecosystem system properties: productivity, stability, persistence, and justice.