**2. Conceptualizing farming systems**

the key pillars of agricultural production. These natural resources like water, soil and natural genetic diversity have been undermined by the current technological advancement and in addition to their degradation, there is also the dependence on nonrenewable fossil fuels and help to forge a system that increasingly takes the responsibility of growing food out of the hands of farmers and farm workers who are in the best position to be stewards of agricultural lands [5]. Factory-farm livestock production is another manifestation of the specialized trend in agriculture. The rise in factory farming is coupled with a world-wide trend toward diets higher in meat and animal products. As demand for meat increases, industrialized methods for animal food production become more profitable and wider spread, replacing more sustainable pastoral and mixed crop-livestock systems [3]. On the other hand, with the development of research on natural resources, the term of eco-efficiency originates. Ecoefficient agriculture means increases productivity while reducing environmental impacts. It meets economic, social and environmental needs of the rural poor by being profitable, competitive, sustainable and resilient. The increased food insecurity and vulnerability of a large number of people worldwide point to a broken food production and distribution system. We need to look at the contribution agriculture should make not only to feed a growing population but also to impact less on the planet's resources. The future food supply equation needs to consider the current reality of lower growth rates for major crop yields in conventional agriculture, eco-efficient approaches to diminish impacts on natural resources, the climate change challenge and the volatility of energy prices [6]. This implies that adoption of ecoefficient practices, approaches and eco-efficient farming systems will surely lead to higher productivity levels while maintaining lesser negative environmental impacts. More clearly, Koohafkan *et al*. [7] reported that, there are many competing views on how to achieve new models of a bio-diverse, resilient, productive, and resource-efficient agriculture that humanity desperately needs in the immediate future. Conservation agriculture, sustainable intensifica‐ tion production, transgenic crops, organic agriculture, and agro-ecological systems are some of the proposed approaches, each claiming to serve as the durable foundation for a sustainable

Therefore, one of the current widely used ideas about food systems is what is called by Francis et al., (2003) the use of integrating approach that combines ecology of these food systems with the economic and social dimensions [8]. Hence, agroecology has been defined as linking ecology, culture, economics, and society to sustain agricultural production, healthy environ‐ ments, and viable food and farming communities [9]. It has been reported that, socio-economic, technological and ecological components constantly interact, creating a complex feedback mechanism that through time has selected for the type of food production systems that we observe today [10]. According to Franci *et al.* [8], agro-ecolgy is defined as the study of the whole food system, embracing both natural and social sciences, and emphasizing systems

In Africa, Andriesse et al., [11] has emphasized that agricultural productivity must be increased to meet the demands of an increasingly urban population, as much as to support sustainable rural population [11]. Most of Africa's poor are rural, and most rely largely on agriculture for

food production strategy [7].

2 Agroecology

thinking and ecological principles [8].

Farming systems, and ways of thinking about them, evolved in space and time. Rapid evolution took place in the last two decades when crop and livestock yields increased, together with concerns about their socio-economic and biophysical tradeoffs [14].

Systems in all sectors of the society, including agriculture need to be examined through the system approach. The term system can imply different things such as a process, procedure or unit [14].

Generally, systems could be classified into natural, social and artificial systems. Natural systems are those that exist in nature. Such an apparent example of these natural systems on which agriculture depends, is rock weathering to form soil, plants sustained by such soil; animals sustained by such plants. The second type of systems is the social form which essentially consists of the entities forming animate population, the institutions or social mechanisms created by such entities, and the interrelationships among/between individuals, groups, communities, expressed directly or through the medium of institutions. The third type is the artificial systems, which are created by humans to serve their purposes. Thus agricultural systems are examples of such artificial systems which are directly dependent on either or both natural and social systems, or indirectly on natural systems through the dependence of social systems themselves on natural systems [15].

Any farm as a unit could be a factory for decision making, it can be a production unit for either crops or livestock or a mixture from both of them. The farmer and other human elements of the farm, the physical and biological environment are the boundaries where this farm as a system operate, and it may change, so it is dynamic. So as pointed out by Dixon *et al.*[16] farming system approach considers both biophysical dimensions and socio-economic aspects at the level of the farm, where most of the agricultural production and consumption decisions are taken. The power of this approach lies in its ability to integrate multidisciplinary analysis of production and its relationships to the key biophysical and socioeconomic determinants [16]. Between the constituents of any farming system, the human, the physical and biological parts, there is complicated interactions between so many detailed components. For example, the human element may be a set of household members including family labour, which in addition to hired labour constitute the multi-nature of each constituent. Also the soil is not only such particles where the plant grow, but a series of physical and chemical characteristics and reactions, all of which are very important for the plant life cycle.

Generally in the literature, there are so many definitions to farm or farming system, each one of them was trying to define the term from different perspective: Okigbo [17] defined a farming system as an enterprise or business in which sets of inputs or resources are uniquely orches‐ trated by the farmer in such a way as to satisfy needs and to achieve desired objectives in a given environmental setting. It could also be defined as a decision making unit as it transforms land, capital, and knowledge into useful products that can be consumed and sold [18]. According to McConnell and Dillon, [15], the term farming system refers to the cultivation patterns used in a plot conceptualized in relation to the farm, other agricultural entities, the socioeconomic and ecological context and the technology available that determine its character [15]. This implies that a farming system is a part of a larger ecological, social, political, economic, cultural environment that is affecting its characteristics. Hence, it is clear from the definitions that farming systems or agro-ecosystems are comprised of many components and agents. The components could be biophysical, socio-economical, and cultural and the agents could be species, ecosystems, households, social communities, scientists, policy makers. Those components and agents are operating on different scales (e.g. local, national, global) while pursuing different objectives.

Rosen [19] defined life as an open process of autopoiesis distinct from the type of external driven organization typical of machines. So building on this definition, Gomeiro et al, [1] mentioned that agriculture implying dealing with life and agricultural systems are also agroecosystems, and agricultural science can be referred to as agro-ecology. Furthermore, Altieri, [20] defined agro-ecosystems as communities of plants and animals interacting with their chemical and physical environments that have been modified by people to produce food, fiber, fuel, and other products for human consumption and processing [20]. In this regard, and as pointed out by Kerr, [21] farms can be considered as ecosystems managed by farmers; thus agriculture is concerned with farmer-managed ecosystems.

Norman and Malton [22] distinguished four main phases in the evolution and development of farming systems approach:

