Systems Science and a Research Challenge


Systems science is a way of thinking as well as a research methodology. Many of us trained in reductionist science are uncomfortable with systems science and systems thinking. Our discomfort comes from inexperience. Systems science is not meant to replace the reductionist approach, but to complement that approach when reductionism is inappropriate. If a problem can be defined and analyzed using our very powerful traditional approach, systems science is not necessary. Systems science is preferred when the problem under study:

1)     is complex;

2)     involves multiple relationships;

3)     involves qualitative variables such as human decision making; or

4)     all of the above.


Many questions in agriculture involve all of the above. This is part of the reason that some farmers are critical of standard agricultural science.


The Challenge Agroecological Research


The ecological processes underlying integrated crop and livestock farming systems are poorly understood. Despite decades of research into attributes and processes regulating primary productivity, nutrient availability, herbivory, pathogenesis, and weed growth in a variety of agricultural systems, we have a generally poor understanding of how communities of organisms interact. Yet this understanding is necessary to unravel the ecological complexity under which various integrated farming systems operate. Better ecological understanding is also needed to design new sustainable systems in which management is based on ecological principles rather than short-term economics, and chemical and energy subsidies.


I believe that by manipulating interactions among organisms and the environment, we can design sustainable food production systems that minimize external inputs and reduce losses, while optimizing for economic yield. This will required a significant investment in research, both on-farm and in more controlled experimental conditions. We must learn to reduce herbicide subsidies by managing crop-weed interactions and selecting for more competitive crop cultivars; and reduce pesticide subsidies through biological controls and complex polyculture farming systems. Most important, we must learn to optimize for energy use efficiency and nutrient cycling through managed intercropping and polyculture systems that cycle materials and energy more efficiently than monoculture systems.


Effective manipulation will require better understanding of the underlying mechanisms that regulate organism interactions under both natural conditions and intensive management. Our understanding of processes such as nutrient availability, herbivory, and plant competition as they are expressed at the organism or population level will provide a basis for the manipulation of these processes at the community and agroecosystem level. Eventually agroecosystem-level integration of crop and animal production will allow us to design low-input management strategies to optimize yield and minimize losses.


Diversification of species over time (rotation), space (intercropping), or time and space (relay cropping), resemble natural plant communities more than monoculture systems. Diversity of species may confer some stability to the system. One stability factor is the reduced risk of total failure due to pests, weather, or price fluctuations. Increased spatial diversity may increase resource utilization efficiency, internal nutrient cycling, and biological control processes. For example, crops often differ in resource utilization of light, water, nutrients due to different canopy and rooting patterns. Also improved efficiency of resource utilization may confer greater competitive ability of the desired crops with weeds. Using available resources more efficiently should allow better recycling of nutrients and less leaky systems. Combinations of crops that differ in nutrient uptake patterns over time and space may minimize nutrient losses.


Agroecosystems that incorporate some of the properties of natural ecosystems in later stages of ecological succession such as forest gardens should have some of the stability and sustainability characteristics that minimize the need for external subsidies. Since there is an export of large quantities of energy and nutrients as yield, some input subsidies will be required. Nevertheless, more sustainable integrated crop and livestock systems must be developed using these principles.


For a further explanation of agroecology, click here, and see the articles posted below.





Bawden, et. al. 1984. Systems thinking and practices in the education of agriculturists. Agricultural Systems. Vol. 13:205-225.


Checkland, P.B. 1981. Systems Thinking, Systems Practice. John Wiley and Sons. New York.


Spedding, C.R.W. 1979. An Introduction to Agricultural Systems. Applied Science Publishers. London.


Spedding & Brockington. 1976. Experimentation in agricultural systems. Agricultural Systems. Vol. 1:48-55.


Wilson, B. 1984. Systems: Concepts, Methodologies and Applications. John Wiley and Sons. New York.


John M. Gerber, April, 1990

Revised slightly, 2003. 2010



For more thoughts on sustainable agriculture research and education, please see:

Moving Toward Sustainable Land Grant Universities and a Sustainable Farming Community by Serving the Public Good; February 2001

Sustainability and Relevance; September 1999

Agriculture is...; 1997

Integrating Research and Extension Education in the Agricultural Sciences; March 1, 1994

Essex Agriculture & Technical Institute Graduation; April 14, 1993

Farmer's and Scientist's Knowledge; 1991

There must be a better way; Summer 1991

Agriculture Systems Ecology Research and Education For A Sustainable Agriculture; 1990

Principles of Agriculture Sustainability; 1990

Sustainable Agriculture Research and Farmer Participation; 1990