Resumen
- Root growth and distribution of crop and forage components of production systems on hillsides could have important effects on nutrient acquisition and plant growth, as well as on soil loss. A long-term field experiment was established in 1994 in the Andean hillsides region of Cauca, Colombia. Soil at the site is medium- to fine-textured Andisol derived from volcanic-ash deposits. Four treatments–cassava monocrop, cassava + cover legumes intercrop, elephant grass forage, and imperial grass forage-were selected to determine differences in dry matter partitioning, leaf area index, nutrient composition, root distribution (0–80 cm soil depth), nutrient acquisition and soil loss. Root biomass of the cassava + cover legumes intercrop was 44% greater than that of the cassava monocrop. The presence of cover legumes not only reduced soil loss but also improved potassium acquisition by cassava. Among the two forage systems, elephant grass had greater root biomass (9.3 t/ha) than the imperial grass (4.2 t/ha). The greater root length density (per unit soil volume) of the former contributed to superior acquisition of nitrogen, phosphorus, potassium and calcium from soil. In addition, the abundance of very fine roots in the elephant grass forage system in the topsoil layers reduced the loss of soil from the steep slopes. These results indicate that (i) the presence of cover legumes can improve potassium acquisition by cassava; and (ii) the use of elephant grass as a forage grass can reduce soil loss in Andean hillsides.