Question

In early nineteenth-century Andean agricultural communities, the cultivation of oca (Oxalis tuberosa) relied heavily on traditional raised-field systems known as waru waru. Modern agro-ecologists have frequently noted that these raised soil platforms served primarily to insulate crops against severe night frosts by retaining heat absorbed by surrounding water canals during the day. However, recent soil micro-stratigraphic analysis indicates that waru waru structures also facilitated complex nutrient cycling: organic sediment dredged from the inter-bed canals was systematically spread across the planting beds prior to seasonal planting. Because oca tubers require soil high in nitrogen and potassium to maximize yield, this periodic canal dredging maintained soil fertility without necessitating fallow periods. Furthermore, while neighboring lowland farming techniques suffered severe soil exhaustion under continuous cultivation, upland waru waru sites maintained consistent agricultural yields for consecutive decades.

Based on the passage, which of the following can be inferred regarding the waru waru agricultural system? Consider each of the choices separately and select all that apply.