Consider the bee. Across a landscape, its search for food brings it into contact with a variety of plants offering nectar and pollen — an example of a classic ecological interaction between two species called herbivory, a type of predation. As an outcome of this interaction, the bee also cross-pollinates its hosts, setting into motion the next generation of plants.
Ecological systems encompass multiple levels of interactions among species such as these. Competition, predation, the cycling of energy as the waste of one species becomes food for another, and a diversity of organisms with overlapping functions all allow a system to remain healthy and adapt to environmental unpredictability (Hillebrand and Matthiessen 2009, Naeem et al 2009).
And these same interactions are present for that bee on a farm, part of a complex system for growing food. Pollination by bees and other animals increases the size, quality or stability of harvests for more than 70% of the leading global crops. These crops also need water, sunlight, nutrients and protection from pests to grow and thrive. The combination of all these processes and many more gives us the food we eat — and, at first glance, the dizzying array of food choices and abundantly stocked grocery stores in many parts of the world may seem to be indicators of a robust food system.
“For years, we have heard that the food system is strained to the point of collapse — yet the dominant paradigm of conventional agriculture continues on.” —Eleanor Sterling and Erin Betley
Yet conventional agriculture — the predominant system of agriculture in many parts of the world — erodes the ecological interactions that make up healthy systems in favor of focusing on one thing: the maximum and efficient production of a commodity.
You can’t produce food without water, but mining precious fossil groundwater over decades to grow crops and feed animals in the High Plains of the United States has dried up creeks and rivers as the water table drops. Complex microbial ecosystems cycle essential nutrients in the soil — but soil health has been degraded through constant application of pesticides and herbicides. The recurrent theme is that conventional agriculture methods focus on monocultures of single species over large areas, rely on increasingly limited resources, depend on relatively stable weather in a world facing climate change, and deplete the very resources agriculture depends on, including soil, water and pollinators.
Cassandra, the ancient princess cursed with the gift of unerring prophecy but whose warnings went unheeded by a disbelieving public, has modern-day relevance when it comes to agriculture. For years, we have heard that increasing demand, inadequate distribution, and eroding ecosystems are straining a food system at the point of collapse — yet the dominant paradigm of conventional agriculture continues on. And indeed, there are many different ways of producing foods depending on where it is grown and who is producing it, and these different ways are constantly changing as humans innovate, all while economic, political, and social factors are at play. These foods are part of a $4 trillion U.S dollar global food economy that is a byzantine mix of supply and demand at a massive scale.
But this dynamic production system has increasingly been built on narrow foundations. We already use almost 40% of Earth’s ice-free land and 70% of our freshwater withdrawals for agriculture (Foley et al. 2011). Almost 40% of global cropland produces just 3 crops: wheat, corn and rice. Conventional agriculture, especially in the United States and parts of Europe, often depends on just one species of pollinator — the honeybee — for the majority of crop species. And colonies of that species are in massive decline, perhaps from the very chemicals we use to bolster conventional agriculture.
Conventional agricultural systems that rely on vast fields of the same plant are a boon for crop pests, providing the opportunity for massive outbreaks in pest species. The resultant use of pesticides and herbicides doesn’t just affect the target pests, but also other species that are quietly working in the background to support healthy farms and agricultural systems — such as those who themselves prey on the crop pests. Massive inputs of chemicals can backfire on us; as Carl Huffaker, an entomologist from UC-Berkeley, has said: “When we kill a pest’s natural enemies, we inherit their work.” We also inherit the work of other species affected by chemicals, including those that help cycle nutrients through soils and those that pollinate crop plants.
Now add an ever-increasing global demand for food atop this fragile, increasingly unstable food system. Annual data published by the UN Food and Agriculture Organization shows that globally we produce 2,800 kcalories of food per capita per day — much more than the minimum daily caloric requirement for a human being — yet almost 1 billion people remain undernourished. And climate change will present many challenges to how we produce our food. Though humans have been transforming Earth’s ecosystems for thousands of years, our current approach to producing our food is not sustainable given the many challenges we face. If we listen to the honeybees, do we hear echoes of Cassandra? Will we heed the sentinel warnings this time around, and how?
We cannot be daunted by the scale of the problem. We will need a network of solutions to feed a growing and urbanizing population. One critical question to ask: How can we work with nature instead of against it to produce our foods?
We can take lessons from healthy functioning ecosystems on natural ecological processes, from interactions between species and from the overall role of diversity in supporting functioning systems. We can harness this knowledge to solve some of the critical problems related to how we produce our food.
One exciting example: in-depth knowledge of the competitors and predators for cereal grain pests has driven the development of an ingenious system of farming in Africa called “push-pull technology.”
For instance, stem borers that prey on cereal plants are attracted to Napier grass (Pennisetum purpureum) and are repelled by another group of plants, desmodium (Desmodium spp.). Planting desmodium among the cereal plants “pushes” the stem borers away, while planting the Napier grass at the edge of a crop plot “pulls” the pests further away. The sticky Napier grass traps the pests and prevents them from returning to the field.
Desmodium does double and triple duty. Through chemical means, desmodium roots outcompete a weedy plant that might otherwise interfere with the cereal plant production. As a leguminous plant, desmodium also fixes nitrogen and controls erosion, thus improving soil fertility. Both desmodium and Napier grass can be fed to nearby farm animals, whose dung could be used to create compost that will fertilize the crops. This diverse, integrated system increases crop yield threefold and relies on local knowledge and locally available plants, providing an independence from expensive external inputs.
“How can we work with nature instead of against it to produce our foods?” —Eleanor Sterling and Erin Betley
More than 30,000 farmers of small-to medium sized farms in East Africa have adopted this technique. Challenges that remain include high labor inputs, spreading the word about this system to and training other farmers, and adapting to the potential impacts of climate change on the plants in the system.
Push-pull technology is but one example of a strategy that comes under several names and nuances — from agroecological systems to diversified farming systems. At its essence, the strategy encompasses managing farms and production systems across a landscape rather than as individual, discrete plots, and working to ensure a rich weave of diversity and interactions across that landscape.
For example, the strategy may be about understanding how the outputs of one system (fish or livestock waste) nurture the growth of another (nutrient intake for plants). It might be seeing how hedgerows or live fences around a field protect the field from wind but also provide habitat for insects that pollinate or controls pests for a crop. Increasingly, larger-scale farming systems are incorporating these techniques, bolstering the ecological interactions that support food production. Full Belly Farm in California, for example, is a diversified mid-sized farm that grows more than 80 crops along with livestock, using cover crops and hedgerows to keep their soils healthy and provide habitat for pest-controlling wildlife and pollinators.
Further afield, managing outlying areas for flood control and water purification support not only biodiversity but also the ingredients that keep a farm system healthy. Diversity within a farm system and its surroundings also helps to ensure resilience in the face of the droughts, floods and temperature extremes anticipated from a changing climate. These diverse food production systems also involve direct incorporation of considerations of people and their livelihoods, including healthier diets and farmer autonomy. Healthy agricultural systems are hallmarked by diversity and integrated cycles that occur across landscapes — and humans are integral parts of the system.
As we strive to learn from nature about how best to produce our food, what should be our guidelines? We know that diversity in how we produce our foods is going to be critical to our collective future as we face the challenges of climate change; natural limits to cheap energy and resources; and, increasingly, globalized and integrated markets.
By listening to the bees and their lessons about how healthy ecosystems function, we can recognize the need for us to create multifunctional and diverse landscapes that conserve supporting ecological interactions — and that in turn allow us to produce nutritious food and promote human well-being.
African Insect Science for Food and Health. 2013. Push-pull: A novel farming system for ending hunger and poverty in sub-Saharan Africa. Retrieved from: http://www.push-pull.net/.
Foley, J. et al. 2011. Solutions for a cultivated planet. Nature 478:337-342.
Hillebrand, H. and B. Matthiessen. 2009. Biodiversity in a complex world: consolidation and progress in functional biodiversity research. Ecology Letters 12: 1405-1419.
Naeem, S., D. E. Bunker, A. Hector, M. Loreau, and C. Perrings. 2009. Biodiversity,
Ecosystem Functioning, and Human Wellbeing: An Ecological and Economic Perspective. Oxford University Press.
United Nations Food and Agriculture Organization. 2009 Food Balance Sheets. Retrieved from http://faostat.fao.org/site/368/default.aspx#ancor.
October 2, 2013. The views expressed above are the authors’ and should not be taken as those of SNAP or its member organizations.