Preserving tropical soil organic matter at watershed level. A possible contribution of urban organic wastes

Abstract

The goal of this paper is to put the issue of preserving Soil Organic Matter (SOM) into a regional, urban-rural, context. In doing so, we apply the method of material flux analysis to a watershed in Boyacá in Colombia. We estimate the order of magnitude of the dry organic matter and carbon fluxes between the rural and urban parts of the region, including estimates on biomass growth, tillage, organic waste, and sewage. These estimates are used to derive potentials for carbon cycling between rural and urban areas. It is shown that (i) for the municipality of Tunja, the treated organic wastes produced in the urban area could add about 30% to the current carbon input into arable soils; (ii) to preserve the organic carbon content in soils in Tunja over the long-term, either, erosion control measures have to be implemented and/or the total treated urban organic wastes have to be concentrated on about 1/5 of the agricultural area. However, such an attempt has to consider the possible trade off between allocation needs (poor farmers on the hillside) and allocation costs (transportation and distribution costs).

Soil carbon sequestration to mitigate climate change

“…Analyzing soils from an urban rural land use gradient, Pouyat et al (2002) observed higher SOC densities in urban than in suburban and rural lands. Preserving SOC at the watershed level may also involve a judicious use of urban organic wastes (Binder and Patzel, 2001).…”

Identifying and investigating pesticide application types to promote a more sustainable pesticide use. The case of smallholders in Boyacá, Colombia

“…MarchSeptember and October-February, corresponding to the two rainy seasons (Gobernación de Boyacá Direccion de Desarrollo Agropecuario, 2004). The texture of soil in the study area is mostly sandy loam or sandy clay loam (Binder and Patzel, 2001). Average productivity rates range between 15 and 17 tonnes per hectare (Ministerio de Agricultura y Desarrollo Rural, 2006).…”

Simulating Human and Environmental Exposure from Hand-Held Knapsack Pesticide Application: Be-WetSpa-Pest, an Integrative, Spatially Explicit Modeling Approach

“…64,65 Average pH of the soil is 5.03 ± 0.31. Total organic carbon is 9.51 ± 3.93% (Walkley Black method), and bulk density is 0.84 ± 0.1 g cm −3 .…”