Terrace Farming

Terrace Farming Definition

Terracing is an important type of landscape alteration in agriculture because it makes use of hillside land that would otherwise be too steep for cultivation. By decreasing the slope gradient, terraces decrease water runoff, which prevents loss of soil and helps retain water for irrigation uses.

Terracing is an intense alteration of the natural landscape’s topography, and the construction of terraces demands a high degree of both labor and expertise. Manual labor is necessary because it is difficult for farm machinery to navigate terraced spaces.

Facts About Terrace Farming

Terrace farming is thought to have first been developed in the Andes Mountains of present-day Peru at least 3,500 years ago. Incas later adopted the practice of terracing from earlier indigenous groups that inhabited the mountainous terrain. Terraces constructed by the Incas can still be seen in places like Machu Picchu.

Fig. 2 - terrace farming along Machu Picchu

For thousands of years, the surfaces of terrace steps have served as an essential source of food for mountainous regions of the world. Today, terrace farming is practiced throughout Southeast Asia, Africa, the Mediterranean, the Americas, and elsewhere.

Rice is often grown in terraced landscapes because it is semiaquatic and requires constant irrigation. Flat terrace steps allow for water to pool instead of becoming runoff that flows down the hillside. Terrace farming can also be useful for crops that don’t need constant irrigation, such as wheat, maize, potatoes, barley, and even fruit trees.

Types of Terraces

Mountainous regions vary in their terrains and climates, so terraces have been adapted to a variety of unique landscapes. Important factors that influence the selection of terrace type are the slope gradient of the hill or mountainside, as well as the expected rainfall and temperature conditions of the area. The two primary types of terraces are bench terraces and ridge terraces, although many other variations exist:

Bench Terraces

The most common type of terrace is the bench terrace. Bench terraces are constructed by cutting and filling the hillside land into steps at regular intervals. These terraces are composed of horizontal platform surfaces and vertical ridges.

The platforms and ridges can be adapted to specific climate conditions and crop needs by changing the angles of these two features. A platform that slopes inward instead of being horizontal can help catch and retain more water. Ridges can be built up vertically and reinforced with stones or bricks. In some cases, ridges can also be adapted to a sloped angle, which allows for vegetation growth on both the bench and the ridge areas.

Both of these bench terrace variations allow for the collection of water on the bench platforms. These constructions would be appropriate for areas that receive low rainfall, for crops that require high amounts of water, or for areas that have a high slope gradient.

Ridge Terraces

Ridge terraces are useful for slowing runoff and soil erosion but differ from bench terraces, as they are not constructed for retaining water. Channels are dug out and the removed earth is then piled to form ridges after each channel.

As rainwater flows down the hillside, any soil that is carried by the runoff is deposited into the channels, and the flow of water is slowed down by the ridges. This can be a useful terrace type when the climate is very wet or when crops do not require as much irrigation. Ridge terraces are more effective for lower slope gradients.

Benefits of Terrace Farming

Let's take a look at some of the many benefits of terrace farming.

Socioeconomic benefits

Terrace farming is an agricultural practice that has persisted through millennia because of the many benefits it provides. A rugged and steep hillside can be transformed into gradual steps that increase the available arable land. Often, terraces are used for subsistence-level food production, meaning that the families or local communities who construct and care for the terraces rely on them for access to food.

In addition to providing food security in these regions, terrace farming can also serve as an important cultural activity. The labor involved in terrace farming often requires cooperation and contributes to local social cohesion. The knowledge and skills required for terrace construction and cultivation are passed down through generations of farmers. In some instances, a terrace from 500 years ago may still be under cultivation today.

Environmental Benefits

Terraces reduce the slope gradient of hillsides, which reduces water runoff. As gravity pulls rain water down a hillside with no terraces to interrupt its flow, the water’s velocity increases and can pull soil down along with it. The flat steps of terraces prevent the water from flowing down and provide a flat surface for it to infiltrate and saturate the soil. This also allows for water to be collected for irrigating crops. Crops like rice can be grown in areas that would otherwise be too dry, thanks to the water catchment provided by terraces.

Conservation of soil is another primary benefit of terrace farming. Soil becomes dislodged and carried away by runoff water during rain events. Soil loss is a pressing issue in agriculture, as important nutrients and minerals are depleted from the soil that is left behind. This can be a financial burden to farmers, who then must supplement these losses with the input of fertilizers. Terraces can thus reduce the need for inorganic fertilizers, which reduces pollution of waterways as these fertilizers are transported through runoff.

Disadvantages of Terrace Farming

The disadvantages of terrace farming primarily stem from the complex interactions of the biotic and abiotic cycles occurring on a hillside.

Over Saturation of Soil

Terraces inherently disrupt the natural hydrological cycle of a hillside, and this can have cascading effects on soil organisms and their functions. If a terrace collects too much water, the soil may become over saturated, causing plant roots to rot and leaving water to overflow. Soil loss and even land and mud slides can happen in these instances, further underlining the importance of constructing the most appropriate type of terrace for the local climate conditions and crop needs. Biodiversity can also be reduced when terraces are planted in monoculture, and this can further disrupt energy and nutrient cycles.

Time

The construction of terraces also requires many hours of labor. Machinery capable of moving earth can't be used on steep or rugged terrain, so everything is typically done with hand tools. In addition, regular maintenance is necessary for terraces to function properly. This process can be very time-consuming and disruptive to the land.

Examples of Terrace Farming

Let's take a look at two common examples of terrace farming; Inca terrace farming and rice terrace farming.

Inca Terrace Farming

The Inca Empire once stretched along the Andes Mountain range from Colombia all the way to Chile. As the largest empire in South America, the Incas had to alter the mountainous landscape with agricultural terraces to feed the population. Incas carved bench terraces and constructed tall ridge walls reinforced with stones. A complex system of canal irrigation was then integrated into terrace construction beginning around 1000 AD. This system of irrigated terraces allowed for the growth of important crops like maize and potatoes by controlling water flow and channeling water down to lower terraces when necessary.

Today, many of these terraced areas are still in use, highlighting the engineering skills of the past Inca Empire. The platforms, called andenes, are farmed primarily by indigenous communities living in the Andes. Traditional crops like maize, potatoes, and quinoa are typically intercropped along the terrace platforms and used for both human and livestock consumption.

Rice Terrace Farming of the Philippine Cordilleras

Fig. 5 - Rice Paddy Terraces in Banaua, Philippines

Named a UNESCO World Heritage Site, the rice terraces of the Philippine Cordilleras have been carved into the steep slopes for over 2,000 years. Both culturally and economically significant, these terraces provide space for rice paddies and catch rainfall for this essential water intensive crop.