The intensive cattle production on the Colombian Atlantic coast causes soil degradation and low productivity on pastures. Silvopastoral systems in Colombia are based on introduced species due to a lack of native species knowledge and a cultural trend to overestimate introduced species. It is necessary to study native species in association with the established pastures to increase productivity and to improve soil properties. This research was based on the Sinú River Valley (18 masl), under Tropical dry forest, in Colombia. The aim of this study was to determine changes in nutrient cycling when native trees are incorporated into grassland systems, according to their diversity. Leaf litter decomposition of two grass species and seven forestry native species were evaluated on four experimental blocks. The results showed that residual dry matter decreased over time and facilitated nutrient release associated with species diversity and its interaction. Nutrient liberation was specie-dependent being markedly higher on G. ulmifolia and P. quinata. The concentration of N/P, P, and Mg was significant and had the highest correlation with leaf litter decomposition. The tested decomposition models showed good performance and small significant differences between them, which confirms its reliability to use them under Colombian tropical conditions.

Andean highland ecosystems (known as paramos) have a great potential to store water and organic carbon, which fulfill the inherent functions associated to the regulation of carbon and water cycles, characteristics linked to their parent material (volcanic ash). However, paramos are at high risk of degradation associated with land use dynamics that affect organic carbon quality in the surface soil. Changes in vegetation cover, with transition from natural forest to tillage and then pasture, make the soil vulnerable to degradation by compaction, erosion, and carbon dioxide emissions associated with increased anthropogenic activity. Despite this cover change, information on soil carbon dynamics in paramos is scarce, impeding conservation management strategies in these ecosystems. This study evaluates the impact of different soil uses within a transect in the Guerrero paramo estimated from soil organic carbon (SOC) stock in the upper meter and carbon condition (expressed as stratification ratio, SR) in the surface soil. Carbon storage varied from 165.2 to 721.9 t ha−1 in the upper meter of soil with SR1 (0–10/10–20cm) between 0.92 and 2.01 and SR2 (0–10/20–30cm) between 0.99 and 2.05. Results of this study highlighted that in the fragile ecosystems than Andean paramos, the geomorphological position in relation to soil uses and management practices conditioned soil carbon availability, affecting pedogenetic processes. SR of SOC associated to anthropogenic intervention activities it does not indicate by itself C sequestration. In future researches it is necessary include additional parameters than net primary productivity and historic vegetation.

Soils provide essential ecosystem services for the existence of ecosystems and biodiversity. It is crucial to understand their quality through the evaluation of ecological processes. However, only some studies estimate the effectiveness of ecosystem restoration based on evaluating soil quality (SQ) indicators. This research evaluated the five most common land-use scenarios in Andean ecosystems within the Natural Reserve of the Civil Society (RNSC) “La Montaña Mágica” under natural forest, coffee plantation, badlands, and active and passive restoration. The main objective was to analyze the physical, chemical, and biological characteristics concerning land use, establish the baseline for SQ indicators in different land use activities, and determine the status of restoration systems for other land uses in the study site. ANOVA and Dunnett's test evaluated SQ parameters. In passive and active restoration, soil bulk density, porosity, and the number of individuals and families of macroinvertebrates were improved. The latter presented low pH and aluminum values but increased potassium compared to other soil uses. The restoration strategies favored changes in SQ indicators due to the contribution of organic carbon, a developed root system, and the recirculation of nutrients in the edaphic system. This study provided information on changes in SQ with soil usage as a practical tool to evaluate ecological restoration methods in natural areas of the eastern Colombian Andes.

This research was implemented in the Colombian Amazon forest area; to assess the effect of Tween-80® surfactant in the degradation of the Total Petroleum Hydrocarbons (TPH) in bioremediation treatments under aerobic conditions in the laboratory and pilot-scale. One control treatment, Natural Attenuation (AT) and four biostimulation treatments with leonardite with four different dosages of Tween-80® were proposed. The efficacy of organic stimulators and nonionic surfactant in soil microbiota was studied at laboratory and pilot scales, the latter in a passive aeration reactor. The test that presented a better performance was carried out with a Convective Flow Reactor (CFR) at pilot-scale. The results showed that bioremediation strategies improved the natural degradation process; the best outcomes were obtained in a treatment that includes Leonardite and Tween-80® (1.5 g/L) with 52% TPH degradation in 80 days (d).Tween-80® produced an effect in TPH solubility, and increased the production of CO2 in distinctive bioremediation treatments in both periods. The kinetics of CO2 production showed that the system required a periodic addition of a co-substrate as well as an increase of soil microbiota through the addition of compost (pilot scale). In this stage more than 76% of contaminant was degraded in 60d.

Understanding the soil moisture behavior in relation to land use in tropical Andean mountain catchments is essential for comprehending water fluxes, ecohydrological relations and hydrological dynamics in this understudied ecosystem. Soils are a key factor of these ecosystems, especially in reference to water level regulation and anthropogenic activities that can alter the interactions, and generate physical, chemical and biological imbalances. In this study, we investigated the relationship between precipitation, soil water content (SWC) and the flow at different pedon scales, and hillslope and microcatchment scales subjected to different land uses. The results showed the relation between the soils uses, topographical conditions and soil moisture at the microcatchment scale. At the pedon scale, soil moisture is higher and with a low variability in depth; high soil moisture content throughout the study period was registered in forest > pasture > coffee agroforestry systems. The topographic wetness index (TWI), despite its adjusted interpretation of the behavior of humidity at the microcatchment scale, is a poor predictor of the behavior of soil humidity at the pedon scale. Pedon water content has a close relation with the precipitation behavior, especially in prolonged dry and humid periods. The soils studied tend to present udic moisture regimes with a dry period of approximately 67 accumulative days per year. The mean flow behavior responds to precipitation and soil moisture behavior at a monthly scale. Understanding the consequences of the land cover changes in relation to soil water behavior, as well as how soil water interacts with the different components of the hydric balance at different scales, allows an understanding of the complex interactions in natural microcatchments under different land use systems.

Soil creep is common along the hillslopes of the tropical Andes of Colombia, where very heterogeneous soils develop on old debris flow deposits and are subjected to abundant rainfall with a bimodal annual regime. In particular, the western hillside of the city of Medellín, Colombia, is comprised of a series of debris and earth flow deposits in which landslides and soil creep are common. To explore linkages between soil creep and hydrology, we selected an experimental site in the western hillslope of the Medellín valley to assess the behavior of water within the soil mass, its relationship with rainfall, and its connection with soil displacement. In experimental plots, we systematically measured runoff, percolation, water table levels, and volumetric water content, for a period of almost 2 years; we also conducted several alti-planimetric positioning surveys to estimate relative displacements of the soil surface. Moisture content of the soil remained above field capacity for most of the year (~68% of the time) and active and quasi-permanent lateral subsurface flow occurred within the upper 80 cm of the profile. The shallow flow likely facilitates the downslope movement. Additionally, our results suggest that displacement magnitudes are largest during the wet season of September–October–November, when a highly humid soil experiences changes in water content, so it is during this time that the effects of expansion / contraction of the soil particles (associated to wetting / drying cycles) contribute the most to the movement. This observational study represents a contribution to the understanding of soil creep in tropical hillslopes, where it responds to the wetting / drying cycles, with the particularities of a rainy weather (>1500 mm/year), warm temperatures (~22 °C on average), and a bimodal precipitation seasonality.