Agroecology is a holistic production method that works at the agroecosystem level. It is based on adopting integrated management for resource conservation as well as diversifying and enhancing synergies among the components of the agroecosystem, balancing energy and nutrient flows and adapting productive activities to local conditions. It promotes a high degree of interaction among its components to preserve biodiversity and attain sustainable production. For example, this method combines polyculture, the presence of animals and the usage of cover crops, organic fertilizers and varying soil depths with soil conservation and ancestral practices (terracing and production in raised cultivation beds).
This method is useful in soils or ecosystems whose ecological equilibrium has been altered by excessive agricultural usage, regions with ancestral agricultural knowledge which may be reintroduced or productive zones requiring diversification for enhanced resilience to changing market or climate conditions. It is particularly important on small farms seeking to reduce reliance on chemical inputs, whether for environmental or economic considerations.
Threats and Impacts it Addresses
By restoring agroecosystem balance, agroecology enhances crop resilience to frost, drought, strong winds, intense rainfall, changes in rainfall patterns and extreme heat. The switch to better practices and holistic resource management contributes to erosion and pest control, promotes income diversification and increases long-term productivity.
- Determine, with expert support, which practices will be developed based on the physical conditions, productive tendencies, local resources and traditional knowledge found at the site.
- Implement these better practices bearing in mind how they interact, so as to establish synergies among components in the agroecosystem.
- Permit self-organization and monitor the presence of beneficial and antagonistic ecological indicators to promote the desired interactions. Since agroecology encompasses much more than abiding by a list of measures, a set of components is presented below, as an example of a diversified production system that could be established with an emphasis on conservation practices. It is assumed that water is abundant and the soil is fertile.
Year 1: Agroforestry system on 0.5 ha of land and conservation agriculture on 2000 m2
Year 2: 500 m2 terrace with crop rotation and crop diversification
Year 3: 2,500 m2 mixed-plant nursery
Inputs and Costs
The calculation given below refers to the cost of implementing a few sample agroecology practices on one hectare of land for a period of three years. The cost of each individual component is the sum of the labour and material costs estimated in the respective fact sheet and adjusted proportionally to its actual area or size in this system. Training is estimated separately and for the combined practices, which involve polyculture, minimum tillage, mulch application and nutrient and pest management without synthetic inputs.
| Components of a three-year agroecology project on 1 ha
| 0.5 ha agroforestry system
| 0.2 ha conservation agriculture
| 500 m2 terrace
| 500 m2 crop rotation and diversification
| 0.25 ha mixed-plant nursery
Economic and Ecosystemic Benefits
Agroecology minimizes the impacts of food production on the environment. For example, the use of organic matter for green manures and mulch preserves the soil and water while fertilizing the soil. Fields with slopes from 1% to 15% not covered with mulch may present a soil loss of 76.6 t/ha, while losses diminish to 2.4 and 0.04 t/ha if 2 and 6 t/ha of mulch is applied, respectively. Regarding the contribution of nutrients, green manures like velvet beans (Stizilobium spp and Mucuna pruriens) can produce up to 150 kg/ha of nitrogen. Using a combination of mulch systems, a group of farmers was able to produce 3 t/ha of maize per year without chemical fertilizers. Even though certain yields of conventional agriculture are higher, when soil loss and consumption of energy, water and other resources are factored in, the benefits of the ecological system become evident (Altieri and Nicholls, 2000).
Holistic agroecosystem management poses challenges in terms of interpreting the causes and effects of procedures and managing the interaction of all the components as if they were a single organism. This requires experience, training and expert assistance. Agroecology focuses less on output than on the general health of the system. By contrast, when only yields are measured it might seem that conventional agriculture is more profitable.
It has been observed that pests have a lesser incidence on the productivity of diversified systems in which agroecology principles have been implemented. This may be because of the synergic effects that fertile soils with good organic matter content have on the biological control of pathogens as well as the greater diversity of insects present in the undergrowth.
Andean traditional practices show how agroecology may be adapted to adverse climatic conditions and difficult topography. For example, terraces reduce the slope, retain water and soil and increase the farming area. In the area that is added, crops and animals are established in diversified systems, such as with multiple potato varieties on the same piece of land or the breeding of cows, sheep, llamas and smaller animals.
Units to Monitor Project Progress: Area under agroecological production (ha).
Unites to Monitor Measure's Impact: Food production (t/ha); expenses for agricultural inputs (US$).
- Altieri, M.A. (1999). Agroecología: Bases científicas para una agricultura sustentable. New York: Sustainable Agriculture Networking and Extension, SANE. UNDP.
- Altieri, M.A. and C. Nicholls (2000). Agroecología: Teoría y práctica para una agricultura sustentable. Mexico: UNEP.
- Manual Básico de Agricultura Ecológica (n.d.). Available at http://www.juntadeandalucia.es.