Agricultural Sector of Machu Picchu

The most widely reproduced image of Machu Picchu the one that appears in travel guides, documentaries, and in the photographs of most visitors always includes the terraces. They are the first element seen upon arriving at the site, descending down the southern slope in parallel bands, and they have such a dominant visual presence that it is easy to treat them as decorative background. A curtain of stone and grass behind which stand the temples and palaces that “really” matter.

That reading is a mistake. The agricultural sector of Machu Picchu is not an accessory to the complex: it is one of its most technically sophisticated parts and one of the most important for understanding how the site functioned as a self-sustaining unit. Without the terraces, without the irrigation system that supplied them, and without the storehouses that held the harvest, the citadel could not have sustained itself.

Where the agricultural sector is located and how it is organized

The agricultural sector mainly occupies the southern slope of the citadel, between the current entrance area where the Guardhouse is located and the Main Plaza. It is the first sector visitors pass through when entering the archaeological site from the control gate, which means that most visitors cross it without stopping to observe it in detail, eager to reach the temples.

The complex is made up of two distinct groups of terraces. The first, in the highest part of the southern slope, is a group of wider and better-built terraces associated with the residential and ceremonial area. The second, on the eastern slope, consists of longer and narrower terraces specifically oriented toward larger-scale agricultural production. This distinction is not merely architectural: it reflects different functions within the site’s productive system.

In addition to the terraces on the southern slope, there are terraces on the eastern hillside of the mountain that are less visible from the main viewpoints, as well as a series of platforms in the sector known as the mountain area that significantly expand the site’s total cultivable area.

The terraces: architecture and function

Each terrace is a horizontal platform supported by a stone retaining wall. In the agricultural sector of Machu Picchu, those walls range in height from about three feet to more than thirteen feet in the sections where the slope is steepest. The stone used is not of the same quality as that of the temples; it is neither polished nor fitted with the precision of fine ashlar masonry, but it was laid with enough solidity to have withstood centuries of rain, earthquakes, and vegetation without collapsing.

The interior of each terrace is not simply compacted earth. Archaeologists who excavated the site including the teams of the Machu Picchu Archaeological Project led by Alfredo Valencia Zegarra in the 1990s found a carefully designed stratigraphy: the base of each terrace is formed by a layer of large stones that acts as drainage, above it is a layer of finer gravel, and on top of that gravel lies the layer of cultivable soil. This layered system serves two simultaneous functions: it prevents rainwater from accumulating and rotting the roots, and it retains enough moisture for crops to thrive during periods without rain.

The depth of the cultivable soil on Machu Picchu’s terraces is greater than one might expect on a mountain slope of this kind. Part of that soil is not local: it was transported from lower areas of the valley to enrich the substrate of the platforms. This logistical effort moving soil uphill at a site without pack animals capable of doing so gives a sense of how seriously the Incas approached the site’s agricultural design.

The irrigation system and water in the citadel

Machu Picchu receives between 1,800 and 2,000 millimeters of annual rainfall, concentrated mainly between November and March. That volume of water, on a steep slope, can be both a resource and a threat. The hydraulic system of the agricultural sector solves that problem elegantly.

The water that supplies the citadel comes from a spring located on the mountain’s northern slope, at a higher elevation than the archaeological site. From that spring, a stone channel a little over 2,300 feet long carries the water to the urban sector, where it is distributed through a series of sixteen stepped fountains. Part of that flow also reaches the agricultural terraces through secondary channels that regulate irrigation of the platforms.

Drainage is equally important. The layered system inside each terrace directs excess water outward through the retaining walls, preventing soil saturation. On the southern slope, the water running off the upper terraces is collected and guided toward the edges of the site without causing erosion in the lower walls. This system has functioned for more than five hundred years with very little modern maintenance, which hydraulic engineers who have studied it consider a remarkable technical achievement.

What was cultivated in Machu Picchu

The altitude of Machu Picchu 7,972 feet above sea level in the sector of the main terraces defines with considerable precision what could and could not be cultivated there. We are at the upper limit of the corn-producing zone in the Andes, which makes the site an interesting case: with the right conditions of sun exposure and temperature, corn can thrive; without them, it cannot.

Pollen analysis and botanical remains found on the terraces have identified evidence of corn, potatoes, quinoa, oca, mashua, and different varieties of Andean tubers. Corn had special importance: it was the prestige crop par excellence in the Inca world, associated with chicha the fermented drink consumed in ceremonies and its production was reserved for the most important administrative and ritual centers of the Tawantinsuyo. The fact that Machu Picchu produced corn indicates that it was a top-tier site within the Inca hierarchy, not a secondary settlement.

The east-facing terraces the ones that receive sunlight from the first hours of the morning would have been especially suitable for corn, which requires direct sun exposure for several hours a day. Terraces in areas with less exposure would have been devoted to crops more tolerant of shade and lower temperatures, such as potatoes and high-altitude tubers.

Some researchers have also proposed that part of the terraces may have functioned as a botanical garden or as a space for agricultural experimentation, where crop varieties brought from different ecological zones of the Tawantinsuyo were tested. This hypothesis is supported by the diversity of microclimates created by the terraces different altitudes, orientations, and degrees of solar exposure and by the Inca tradition of using royal estates as spaces for agricultural innovation.

Storehouses or qollqas

The agricultural output of the terraces was not consumed immediately. Part of it was stored in the qollqas, the storehouses distributed throughout different parts of the site. At Machu Picchu, the qollqas are located mainly in the most ventilated areas of the agricultural sector, in elevated positions where the circulation of cold air helps preserve food.

The choice of location was not arbitrary. The Incas understood empirically that cold and ventilation reduce moisture and delay decomposition. Storehouses at higher elevations, exposed to the wind and far from areas with greater heat buildup, made it possible to preserve tubers, dehydrated grains, and charqui for months without spoilage.

The scale of the qollqas at Machu Picchu is relatively modest compared with the great storage centers of the Tawantinsuyo, such as those at Huánuco Pampa or Hatun Xauxa. This is consistent with the site’s function: it was not a region-wide redistributive center, but a royal estate with the capacity for self-sufficiency during extended periods of occupation.

The agricultural sector as a climate regulator

One of the most interesting findings of modern studies on Machu Picchu’s agricultural sector is that the terraces do not just produce food: they also modify the site’s microclimate. The earth-filled platforms, by absorbing solar heat during the day and releasing it slowly at night, raise the minimum temperature in the cultivated areas by between 2 and 3 degrees Celsius compared with the ambient temperature.

That difference may seem small, but at 7,900 feet of altitude, where nighttime frosts are frequent during the dry season, two degrees can determine whether a crop survives or is lost. The terraces functioned as heat accumulators that protected crops from frost, extending the productive season beyond what would have been possible on the same ground without those structures.

This effect was documented by agronomist Clark Erickson, who worked on the reconstruction and reactivation of Andean terraces in the Lake Titicaca highlands and found the same phenomenon of thermal regulation in similar systems. The conclusion is that the Incas did not build terraces only to gain cultivable surface area: they built them because they knew or had learned empirically that they transformed the climatic conditions of the environment.

The current state of the agricultural sector

A significant portion of Machu Picchu’s terraces was restored during the twentieth century, especially in the sectors most visible from the main viewpoints. That restoration has been the subject of debate among archaeologists: in some sections, retaining walls were rebuilt with stones that are not original and with techniques that differ from Inca methods, complicating the archaeological interpretation of those structures.

Peru’s Ministry of Culture and the National University of San Antonio Abad of Cusco have carried out survey and documentation work on the agricultural sector in recent years, with the aim of distinguishing more precisely between original and restored sections and assessing the structural condition of the walls in the areas that have not been intervened.

Since 2019, as part of the site management program, cultivation has been reintroduced on some terraces in the agricultural sector using varieties of Andean plants. This initiative has a dual purpose: to demonstrate the productive viability of the terraces and to contribute to the maintenance of the soil on platforms that, without agricultural use, tend to compact and lose the structure that makes them functional.

What to observe when visiting the agricultural sector

Most visitors cross the agricultural sector in the first few minutes of their visit, with their eyes fixed on the main viewpoint and the panoramic view of the citadel. It is worth slowing down and paying attention to a few details:

• The stratigraphy of the retaining walls: in sections where erosion has exposed the base of a terrace, it is possible to see the layers of stone, gravel, and soil that make up the inside of the platform. That cross-section is more revealing than any written description.
• The variation in wall height: the terraces are not uniform. In the sections where the slope of the mountain is steeper, the retaining walls are noticeably higher. Observing how that height changes along the hillside gives an idea of the leveling work required to build horizontal surfaces on such uneven terrain.
• The Guardhouse: located at the highest point of the agricultural sector, on the southern edge of the citadel, it offers the most recognizable panoramic view of Machu Picchu. It is also one of the best-preserved buildings at the site, with its reconstructed thatched roof.
• The channels between terraces: in some sections of the route, the stone channels that carried irrigation water from one terrace to the next are visible. They are small structures that are easy to overlook, but they are part of the same hydraulic system that supplies the fountains in the urban sector.

The terraces of Machu Picchu are the part of the site that most directly connects with the question of how the people who lived there sustained themselves. The temples and the Intihuatana speak of the power and knowledge of the Inca elite; the terraces speak of labor organization, of the relationship with the land, and of the ability to build systems that function for centuries. In that sense, they are just as eloquent only in a different language.