Traditional practices for fragile sandy soils in semi-arid regions

Photo credit: Agricultures Network

During the short rains manure is dug into the fields. Photo: Alejandro Bonifacio

Traditional fallows support resilient farming on semi-arid sandy soils

EXCERPT

 

The arid southern highlands of the Bolivian Andes are a harsh environment for even the most hardened farmers. The ‘quinoa boom’ and the move to mechanisation have led to shortened fallows and a drastic drop in soil organic matter. The dry sandy soils and the natural vegetation they support are increasingly degraded, but in the face of climate change and higher risks of drought, frosts and hailstorms, technical recommendations pay little attention to soil health. Farmers in the community of Lloco, however, have preserved their traditional practices that care for their fragile sandy soils and maintain resilience.

After the tallest shrubs are cut and left on the ground as mulch, manure from the grazing areas is piled on the fields, dug into the soil and covered with sikuya straw to protect it from erosion and maintain moisture. Photos: Alejandro Bonifacio - http://www.agriculturesnetwork.org/magazines/global/soils-for-life/traditional-fallows/shrubs.jpg
After the tallest shrubs are cut and left on the ground as mulch, manure from the grazing areas is piled on the fields, dug into the soil and covered with sikuya straw to protect it from erosion and maintain moisture. Photos: Alejandro Bonifacio – http://www.agriculturesnetwork.org/magazines/global/soils-for-life/traditional-fallows/shrubs.jpg

Fallow, manure and mulch

After a ‘typical’ 20 to 30 year fallow, site preparation begins 3-12 months before the rainy season. The tallest shrubs are cut, leaving cut material on the ground as mulch and leaving the smaller shrubs and herbs alone. Manure is moved from grazing areas and piled where the shrubs were cut and covered with straw to reduce nutrient loss from strong winds that are common. Most families in Lloco collect manure from their own llama herds, otherwise they have to exchange or buy it from families with larger grazing areas.

In the middle of the short rains which usually last only two months (January and February), manure is spread evenly over the fields and hoed in, before the soil is covered with straw from a common unpalatable local grass called sikuya. The straw protects against erosion, against the sun, and reduces the soil from drying out during the cold and dry months. Timing of this activity is crucial, to maximise soil moisture and nutrients, in preparation for planting six months later. Crops are sown in advance of the rainy season, so that there is enough time to complete a growing cycle before the onset of winter. Potatoes are planted for two to three consecutive years before being followed by quinoa and barley. The typical rotation may be described as potato-potato-potato-barley, potato-potatoquinoa-barley or potato-quinoa, depending on the soil fertility and soil humidity.

Read the full article: Agricultures Network

Author: Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.

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