A road more than 20,000 miles (32,000 km) long climbing up some of the world’s most impenetrable terrain. Today the Great Inka Road – winding its way among dizzying peaks and tropical lowlands, through Colombia, Ecuador, Peru, Bolivia, Argentina and Chile – is once again attracting attention. Added to the UNESCO World Heritage list last year, celebrated in an exhibition in Washington through June 2018, this road is the backbone of a set of engineering projects that enabled the Inca to grow potatoes, quinoa and maize at altitudes up to 4,000 meters.
These are steep, rugged lands; the climate is harsh, but the Inca Empire’s crops were hardy, sweet and abundant. Harmony with the Earth, Pacha Mama (Mother Earth in the Quechua language), was considered sacred. When the Spanish Conquistadors arrived in the early 1500s B.C., nearly a million hectares of Andean lands were covered in terraces rising up the mountainsides, with irrigation canals.
The Inca terraces are considered among the best in history, with those dry stone walls made of variously sized and angled rocks that absorb heat during the day and release the warmth slowly at night, keeping the plants warm during the coldest hours. Gravel and sand mixed into the earth helped retain moisture during droughts, and when it rained they kept the soil from expanding and shattering the walls.
The “waru-waru” technique, for example, dates back some 3,000 years and combines two elements: raised beds of earth in which the crops were planted, and channels alongside them collecting water and draining off the excess, preventing damage during floods and creating a frost-preventing microclimate and limiting the more harmful effects of the extreme temperatures. This system keeps the soil fertile with the sediments, lime and algae from the irrigation channels that turn into nutrients to be added seasonally to the soil. This technique, revived for the first time thirty years ago, was brought back under a UNESCO project and is used today in many other countries, including China.
Biodiversity, really exceptional in the case of some crops, is still today one of the outstanding characteristics of these regions. One example will do: the potato. Lima’s International Potato Center boasts the world’s largest collection of tubers: 4,500, including 3,000 indigenous varieties. But the Inca did not grow just one crop: on the same plot of land they planted maize, quinoa and squash together, resulting in the plants drawing mutual benefits from the mix and growing lushly.
For the past 25 years, and increasingly, local Peruvian communities – but also others – have been trying to revive the ancient engineering and agricultural wisdom of the Andes, making poor, marginal soils productive without fertilizers and pesticides, with a more efficient use of water. This is also due to the efforts of organisations like the Cusichaca Trust that work to return the Andes to production based on the model and the infrastructure passed down by the ancestors.