Principles of a Systems Approach to Agriculture

Abstract

A systems approach is needed to understand and manage a ‘farm’. This chapter examines the definition and concepts of farm systems, their structure, operation and management, the relationships among internal and external factors, response to changing circumstances, and modifications to deal with change. Study of a system requires definition of goals and objectives, boundaries and the structure and function of its components. Feedback mechanisms and interactions are important features of farm system structure and operation. Farm systems can often be better understood through analysis and the study of their sub-systems; and circle or problem-cause diagrams can assist this. Farmers design their systems to make best use of the prevailing climate and soil but a wide range of technological, commercial, social, political and personal factors determine farmers’ goals and management. Important characteristics of systems include: productivity, profitability, efficiency, stability, sustainability, equity, flexibility, adaptability and resilience. Efficiency of resource use should be optimised, bearing in mind Liebscher’s Law of the Optimum. Efficient use of energy and water are necessary for profitable production.

Appendices

Supplement to Chapter 1

Emergy: A New Approach to Environmental Accounting

• Gloria Rótolo,
• Charles Francis &
• Sergio Ulgiati 

1. National Institute of Agricultural Technology (INTA), Oliveros Agriculture Experimental Station, Oliveros, Argentina

   Gloria Rótolo

2. University of Nebraska–Lincoln, Lincoln, NE, USA

   Charles Francis

3. Department of Sciences for the Environment, Parthenope University of Naples, Naples, Italy

   Sergio Ulgiati

Overall Emergy Concepts

Emergy is defined as the whole available energy (based on a common unit, usually solar energy) that is used directly and indirectly to obtain a product or service (Odum 1996). It is the energy ‘memory’ of the product, and accounts for all the available energy supplied by nature and society that is invested in producing a certain output. It therefore provides a combined ecological-economic evaluation. To understand the concept of emergy or energy memory, it is necessary to appreciate its systems foundation and the background of its ‘supply-side approach’, which refers to the idea of accounting for all the flows that have contributed to a product or service along the chain of its development.

The emergy concept is built on two main pillars. One of them is Systems Ecology (Odum 1983), deeply rooted in General Systems Theory (Von Bertalanffy 1968). It conceives any ecosystem as a global entity, made with interconnected components, and only understandable as a whole. Today, almost all ecosystems in the world have been directly or indirectly modified by human interventions. Therefore, within these ecosystems, nature and society are interacting and co-evolving through time. Systems Ecology is the study of the ecosystem ‘as a whole’, encompassing the overall performance of the system, and also the details of its design, since the overall behavior of the system—i.e. what characterises it—is produced from the interactions of separate parts and mechanisms (Odum 1983).

The second pillar on which the emergy concept relies is the biophysical laws that govern the systems. According to Odum (1996), each socio-economic system acts and evolves within, and together with, the natural system where it is immersed, over a hierarchy of scales of time and space. This simply means, first of all, that all socio-economic systems—including agricultural systems—are subject to the principles of irreversible thermodynamics⁷ that determine their self-organisation⁸ patterns, from the small-scale of chemistry and biology up to a global scale, through the identification of energy flows used over the whole metabolic chain of systems. In particular, those designs that maximise power output from the resource available prevail, as suggested by Lotka’s Maximum Power Principle (Lotka 1922a; b). Successful systems develop structures that maximise useful resource consumption and production, by feeding back matter and information. In order to take quality of flows into account, Odum (1983, 1996) restated Lotka’s principle via the emergy concept as a Maximum Empower Principle. The revised statement is:

Systems that develop the most useful work with inflowing emergy sources, by reinforcing productive processes and overcoming limitations through system organisation, will prevail in competition with others.

or, in other words,

In self-organisation patterns, systems develop those parts, processes, and relationships that maximise useful empower (throughput flow of emergy).

It is important that the term ‘useful’, i.e. something that produces a positive consequence, is used in these two statements. For example, drilling oil from wells and then burning it off may use oil faster (in the short run) than refining and using it to run machines. However, it will not compete, in the long run, with a system that uses oil to develop and run machines that increase drilling capacity and ultimately the rate at which oil can be supplied.

Within a maximum empower and natural selection framework, maximum efficiency as defined in classical thermodynamics textbooks is no longer the driving prerequisite. First of all, complex systems adapt to environmental conditions by optimising, and not necessarily maximising, their efficiency, so that global maximum power output can be achieved and maintained. Maximising global production is the goal, which is reached by ‘choosing’ the most appropriate efficiency for each of the co-products. As a consequence, resource throughput is also maximised consistently with availability of resources. In this way, systems tune their thermodynamic performance according to the surrounding environment.⁹

In general, when resources are abundant, the advantage goes to the system which is able to draw on them faster than others, regardless of their efficiency. When resources decline, efficiency must grow, in order to generate the maximum possible product within the existing constraints based on smaller throughput. Although an efficiency increase is generally achieved at the expense of process speed (Odum and Pinkerton 1955).¹⁰ Societies tend to deplete most of the known and accessible resource storages, on both the source side (reservoirs of nonrenewable resources such as oil, minerals, fertile soil) and sink side (clean air and water, ecosystem integrity). Resources become increasingly scarce, due to increased use per person and increased population. Therefore, according to the Maximum Empower Principle, fast consumption is no longer a winning strategy for survival and must be replaced by increased global efficiency (doing more with resources available).

Within the new framework of Emergy Analysis and Maximum Empower Principle, it is possible not only to integrally analyse these complex nature-socio-economic contexts as a whole system—by accounting for the energy flow throughout it—but also to consider feedback mechanisms among the system’s components that derive from self-organisation processes. Depending on the way these feedback flows work within the system, the self-organisation process will allow the survival of the system as it is, or its evolution to other forms depending on which of the components are more reinforced. For example, the excess use of agrochemicals on crops might provoke the appearance of resistant species that have been evolving under the threshold level for damage by the chemical, and that now become major pests.

Howard T. Odum and his colleagues, working on the evaluation of ecosystems at different scales, found it feasible to integrate the natural and socio-economic systems by introducing the idea of energy quality within a system driven by multiple flows of energies. Energy quality refers to its form and concentration. Energy of one form is not equivalent to energies of another form in their ability to do work. These different forms contribute differently to biophysical processes (Ulgiati et al. 2007; Brown and Ulgiati 2004a and b). For example, solar and fuel energies are important for the functioning of agricultural systems. However, their contributions to the system are very different, that is, they are different in form and concentration, or in their quality. In photosynthesis solar energy cannot be replaced by fuel energy; they have different roles in the system. Thus, when adding up different forms of available¹¹ energy that have contributed to a process or service, they must first be converted to a common form of energy (Odum 1996). Solar available energy is utilised as a common unit in the evaluation of the integrated system since it could be considered as a reference input for almost every system. This common form of energy when used in relation to obtaining a service or product is called emergy (measured in solar equivalent joules, abbreviated seJ).

Emergy evaluations are sometimes referred to as Emergy Synthesis (Brown and Ulgiati 2004a and b) since they are designed to build understanding by grasping the wholeness of the system from the top down instead of breaking it apart and building understanding from the pieces upward (Brown et al. 2000). Emergy actually is the available energy (i.e. the potential work) consumed in transformations. Unit emergy values or emergy intensities may be defined as the emergy input per unit of output (energy, mass, time or money). Thus transformity is the emergy required to make something per unit energy output (seJ/J). Specific emergy is the emergy per unit mass (seJ/g), and emergy per unit money refers to the emergy supporting one unit of economic product (seJ/unit currency) (Table 21.2 column 4 and Table 21.4). These are practical measures of system efficiency. Further explanation of emergy intensities can be found in Brown and Ulgiati 2004.

In an emergy study, system boundaries are established, and diagrams drawn using the energy systems language (Fig. S1.1, Figs. 21.3, 21.4 and 21.5). These diagrams are necessary to visualise and help quantify the components and flows as well as the renewable and non-renewable natural resources, purchased inputs, labor and services and all their interactions that are involved in the evaluation. Therefore, diagrams allow us not only to have an overall view of the resources and components that contribute to the product, of their interactions and their potential to ‘organise’ the input information, but also to help avoid double counting of flows coming from the same source. Once the diagram is drawn, the value of each input flow is accounted for and organised in tables (e.g. Table 21.2). Tables allow us to quantify the information by listing the resources, purchased inputs, labor and services flows and their corresponding raw and emergy values that contribute to the system dynamics as well as to its final product or service (Table 21.2).

If the table is for flows, it represents flows per unit time (usually per year). If the table is for reserve storages, it includes those storages with a turnover time longer than 1 year. Dynamic models for storage variation may also be constructed and run.

The final step is to calculate emergy indices that relate the emergy flows of the economy to those of the environment. This enables prediction of economic viabi­lity, carrying capacity, and system performance (see Chap. 21) that can be used to inform policy decisions.

The emergy value of a particular component represents all the energy transformations that have occurred throughout its chain of development. Therefore, the different places occupied by each symbol denote a hierarchical organisation. The higher the organisational level of a component in the system, the higher the ‘supply-side’ energy quality and the smaller the amount of available energy of the carrier. For example, grazing steers have a higher energy quality than pasture because more energy transformations were needed over the whole metabolic chain (roughly: solar radiation → rain → pasture → protein). The relatively small available energy of their body is the final ‘carrier’ of the much larger available energy provided by the sun to the photosynthetic process that generated the pasture. As a consequence, total protein output represents the convergence of the biosphere work and services that supported the growth of the steers. Due to the large work needed to generate the protein (large finished steers), production would have been discontinued by natural selection—if such a hierarchical quality of steers were not ‘recognised’ on the larger scale and rewarded economically by society.

For a more complete explanation of the theory and methodology of the emergy concept and emergy analysis, see Odum (1983, 1996) and Brown and Ulgiati (2004a). Haw and Bakshi (2004) enrich the concepts of emergy analysis, discussing specific applications, while Herendeen (2004) and Brown and Herendeen (1996) analyse differences and similarities between embodied energy, energy, and emergy analysis methods.

Emergy as a Valuation Method

Usually money is used to value most of the outputs produced by the interacting nature-society system. The usual concept behind market value, what people are willing to pay for a product, focuses on the so-called receiver-side value, i.e. a concept of value based on the usefulness perceived by the receiver of the product. It is a different concept from that used in emergy analysis, a ‘donor value’ or supply-side value, according to which something has a value depending on what was invested to make it within an environmental or socio-economic chain of metabolic processes. The measure of value through emergy evaluations is independent of the market oscillating dynamics where prices can go up or down according to abundance or scarcity or just advertising efforts. Market values are not helpful for direct valuation of contributions from the environment since usually they respond inversely, that is prices are lower when product on offer is larger, although usefulness is also large because of the amount available to many users (Odum 1996, p 260). For example, in the market concept, when water is scarce, it is assigned a higher money value than when it is abundant. However, it is when water is abundant that it contributes more real wealth to the economic system and the standard of living of the people.

Conclusions on Emergy Analysis

The emergy concept and methodology can only be utilised within a whole systems context. It is a comprehensive measure of the work of nature and society, converted to common units (Ulgiati et al. 2007). An emergy study accounts for all energy and matter input flows that contribute to a process, integrating or amalgamating the major inputs from the human economy with those coming ‘free’ from the environment, (Brown and Ulgiati 2004a and b).

Although the emergy method is not yet widely used for the study of economic systems, it is a comprehensive and highly useful method for analysing whole systems. More complex than neoclassical economic evaluation, more comprehensive than conventional energy analysis, the emergy approach takes into account both the environmental and the societal contributions to a given product by considering the whole system in which that product is produced. This is a more realistic and long-term assessment of the cost to society as well as to the environment. It provides a holistic basis on which to make management decisions as well as policies capable of supporting long-term sustainability. Further examples of the applications of this concept are provided in Chap. 21 of this book.