PREHISPANIC AGRICULTURAL TERRACES
Prehispanic civilizations such as the Inca and the wari constructed around 1 million hectares of agricultural terraces in mountain valleys throughout Peru. Much of this infrastructure has been damaged or abandoned since the Spanish conquest; firstly because the Spanish moved populations away from their villages to work in mines elsewhere and more recently due to migrations away from the rural communities due to the social unrest in the 1980s and part of the 1990s.
In some places such as in the Colca canyon and in the Sondondo valley these terrace systems continue to be farmed and maintained efficiently. Through studying these systems the many advantages of terrace farming can be documented. Some of the most important are:
- An efficient use of water. There is very little surface run off as the platforms are nearly flat.
- Sufficient water is retained within the terrace soils to maintain these humid. Excess percolates down to the one below.
- Locally available materials such as stone, gravel and clay are used in the construction thus saving on costs and enabling the local communities to maintain their systems themselves.
- The stones used in the construction absorb heat during the day and release it at night – creating micro climates which offer some resistance against heavy frosts. This stimulates a more rapid germination, improved growth and results in increased production.
- Soil erosion is massively reduced.
- The moist warm conditions in the soils favor the activities of microorganisms which contribute to the fertility of the soil.
- Terrace systems offer crop yields of 30% to 80% above that achieved on sloping field systems. At 3,300m and below it is possible to achieve two harvests per year or sometimes three with horticultural crops.
In the Chicha Soras valley there are more than 6,000 hectares of terraces though 70% are not well preserved. In the Sondondo valley there are around 4,000 hectares, of which the majority are in excellent condition. When maintaining or rehabilitating terraces and related irrigation systems such as canals and reservoirs it is best to use only locally available materials such as stone, sand, clay and juice from the cactus giganton. By doing so material costs are kept to a minimum and the local farmers will be able to continue to maintain their terraces in the future.
Within the Andean Region of Peru around ½ million hectares of currently under utilized land could potentially be brought back into full production. At a time of climate change terrace farming is undoubtedly the most efficient form of cultivation in mountain valleys.