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Browsing Research Data by Author "Olivera, Edgar"

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    ItemOpen Access
    Data-land use as a driver of soil fertility and biodiversity across an agricultural landscape in the central Peruvian Andes
    (Colorado State University. Libraries, 2017-01) de Valença, Anne W.; Vanek, Steven J.; Meza, Katherin; Ccanto, Raul; Olivera, Edgar; Scurrah, Maria; Lantinga, Egbert A.; Fonte, Steven J.
    Land use change and intensification in agricultural landscapes of the Andean highlands have resulted in widespread soil degradation and a loss in soil-based ecosystem services and biodiversity. This trend threatens the sustainability of farming communities in the Andes, with important implications for food security and biodiversity conservation throughout the region. Based on these challenges we sought to understand the impact of current and future land use practices on soil fertility and biodiversity, so as to inform landscape planning and management decisions for sustainable agroecosystem management. We worked with local communities to identify and map dominant land uses in an agricultural landscape surrounding Quilcas, Peru. These land uses existed within two elevations zones (low-medium, 3200-3800 m and high elevation, 3800-4300 m). They included three types of low-medium elevation forests (Eucalyptus, Alder and mixed/native species), five pasture management types (permanent pasture, temporal pasture (in fallow stage), degraded pasture, high-altitude permanent pasture and high-altitude temporal pasture (in fallow stage)) and six cropping systems (forage crops, maize/beans, and potato under four types of management). Soil fertility was evaluated in surface soils (0-20 cm) with soil physicochemical parameters (e.g., pH, soil organic matter, available nutrients, texture), while soil biological properties were assessed using the abundance and diversity of soil macrofauna and ground cover vegetation. Our results indicated clear impacts of land use on soil fertility and biological communities. Altitude demonstrated the strongest effect on soil physicochemical properties, but management systems within the low-mid elevation zone also showed important differences in soil biological communities. In general, the less-disturbed forest and pasture systems supported more diverse soil communities than the more intensively managed croplands. Degraded soils demonstrated the lowest overall soil fertility and abundance of soil macrofauna, but this may be reversible via the planting of Alder forests. Our findings also indicated significant covariation between soil physicochemical parameters, soil macrofauna and ground vegetation. This suggests that management for any one of these soil properties may yield unintended cascading effects throughout the soil subsystem. In summary, our findings suggest that shifts in land use across the landscape are likely to have important impacts on soil functioning and biodiversity.
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    ItemOpen Access
    Dataset associated with Vanek et al., 2020, "Participatory design of improved forage/fallow options across soil gradients with farmers of the central Peruvian Andes"
    (Colorado State University. Libraries, 2020) Vanek, Steven; Fonte, Steven; Ccanto, Raul; Meza, Katherine; Olivera, Edgar; Scurrah, Maria
    Land use intensity is increasing in Andean smallholder systems, and innovations are needed to sustain soil fertility and productivity of potato-cereal rotations with shortening fallow periods. In collaboration with farmers in central Peru, we assessed forage-based fallows in 58 fields across three production zones over three years. Fallow treatments selected with farmers tested grass-legume mixtures with different combinations of Vicia Sativa (vetch), Avena sativa (oats), Lupinus mutabilis (Andean lupine), Trifolium pratense (red clover), Medicago sativa (alfalfa), and Lolium multiflorum (ryegrass) compared to an unseeded control fallow with natural revegetation. The ability of fallows to quickly cover soil was tested, as was their biomass production in years one and three. Following the incorporation of fallow vegetation in a sub-set of nine fields, we also tested fallows' effects on soil pH, available phosphorus (P), permanganate-oxidizable carbon (POXC) and potato yield. In year one managed fallows produced from 1.9 to 5.4 Mg ha−1 of forage biomass compared to 0.5 to 1.1 Mg ha−1 in unseeded controls. Managed fallows also exceeded controls in nutrient uptake, soil cover, and forage quality (lower lignin and higher protein content). First-year biomass of vetch and Andean lupine responded differently to soil pH in fields, indicating that appropriate fallow options likely depend on soil context. After three years, total biomass did not differ among treatments. However, legumes had greater biomass in treatments employing perennial species (0.79–1.18 Mg ha−1 of legumes) than in controls (0.15 Mg ha−1). Potato yield and soil fertility was not reduced in managed fallows compared to the control, and an alfalfa + liming treatment yielded higher than the control (p < 0.05). Diseased tubers were also less prevalent in fallows containing ryegrass and clover, versus other treatments (2.7 % vs. 4.7 % diseased; p = 0.05). In a post-hoc analysis considering 41 treatment plots with contrasting cutting regimes, plots that were cut repeatedly throughout the fallow period had more negative changes in POXC than those cut initially and then left to regrow (p = 0.04). In evaluation workshops, farmers emphasized forage production, potato yield, and potato tuber health as evaluation criteria for the fallows, and ranked the alfalfa + liming treatment as the best. In Andean communities with shortening fallow periods, forage-based fallows represent a promising, multi-functional option to maintain soil health and productivity while generating additional sources of high-quality forage. However, future research should examine long-term nutrient and carbon balances under different forage removal scenarios, as well as designing fallows for varied agroecological contexts.