Question

Two sources address the traditional volcanic dry-farming viticulture (*enarenado*) practiced in La Geria, Lanzarote (Canary Islands):

Source 1 (Audio Broadcast Excerpt)
*From an interview on the agricultural program 'Voces del Campo' with agronomist Mateo Delgado:*
"When volcanic eruptions blanketed fertile valleys with porous volcanic gravel (*picón*) in the 18th century, local viticulturists adapted by digging conical depressions into the soil. This layer of lapilli serves as a natural moisture trap: it absorbs nocturnal humidity from ocean breezes and prevents soil water evaporation caused by intense solar radiation and Atlantic winds. Nevertheless, because each depression contains only an individual vine surrounded by a semicircular stone wall, field management and grape harvesting must be performed entirely by hand rather than standard machinery."

Source 2 (Agronomic Research Summary)
*From a published study on arid-zone agricultural heritage:*
"The *enarenado* system of Lanzarote relies on a 20–30 cm stratum of basaltic tephra to sustain viticulture in a desert-like biome with under 150 mm of annual rainfall. Microclimatic analyses indicate that the mulch's porous structure drastically minimizes subsurface evaporation while capturing ambient dew. While this geological adaptation allows high-quality viticulture without external irrigation, the geometric layout of individual funnel-shaped pits (*hoyos*) and protective windbreak walls (*abrigos*) completely precludes the introduction of tractor-based harvesting machinery, keeping labor requirements elevated."

Which of the following conclusions is directly corroborated by both sources?