Fragile Lands of Latin America Strategies for ... - PART - USAID

Agricultural Terraces in Peru's Colca Valley 21 9
Plate 2 Rebuilding abandoned agricultural terraces in Coporaque, Arequipa, Peru, by
placing new wall base stones and building the wall upwards to retain the soil.
rear of the new terrace if the original topsoil is thin. If that occurs,
organic material may be worked into the new exposed soil surface.
Most often, a terrace is damaged when waterlogged soil bursts the
retaining wall and spills forth. Careless wall repair hastens hrther wall
failure. Builders blame poor masonry techniques or dry soil construc-
tion for broken walls. Builders prefer to terrace with wet soil since dry
soil is porous and will quickly become saturated following heavy rains,
thus provoking sudden, early bursting. Common mistakes cited include
not fitting wall stones together tightly, or failure to press stones tightly
against the earthen fill behind. In the latter case, a gap forms between
the wall and fill causing the wall to collapse.
Terrace reconstruction duplicates the labor techniques of construc-
tion, except that soil spilled from ruptured walls has to be thrown
back upslope and re-walled. Workers trench down to the original base
to remove the fallen and buried stones from the original wall. The wall
is rebuilt while the fill stones and soil are carehlly re-packed in behind
the wall and tamped down. Building bench terraces from scratch may
not require a great deal more time than rebuilding abandoned ones.
When reconstructing fields, masons replace up to 80 percent of the
BEST AVAILABLE COPY