ECOSER PROJECT: TOWARD A BETTER UNDERSTANDING OF THE
MECHANISMS OF CARBON STABILIZATION IN AGRICULTURAL SOILS
AMENDED WITH MUNICIPAL ORGANIC WASTES
C. Plaza, R. Sanz, P. J. Hernáiz, J. C. García-Gil, P. A. Soler-Rovira, J. M.
Fernández, D. Hernández, I. Haller, and A. Polo
Instituto de Ciencias Agrarias, Centro de Ciencias Medioambientales, Consejo Superior de
Investigaciones Científicas, Serrano 115 dpdo., 28006 Madrid, Spain
STATE-OF-THE-ART
Land application of municipal organic wastes, especially to organically-depleted agricultural soils, is believed to be an efficient practice for improving soil quality and crop
production, while reducing the amount of waste to be disposed of in landfills or burnt in incineration plants, enhancing C sequestration, and thus helping head-off the global
warming. According to current concepts, the biogeochemical pathways responsible for exogenous organic matter stabilization in soil include (a) selective preservation and
formation of recalcitrant organic compounds (biochemical protection), (b) occlusion within soil aggregates (physical protection), and (c) association with mineral surfaces
(chemical protection). To date, however, how these protective mechanisms act and interact in soils amended with municipal organic wastes remains largely unknown.
OBJECTIVES
The main objective of the ECOSER project is to develop a better understanding of the processes controlling the transformation and stabilization of organic matter in
agricultural soils amended with municipal organic wastes, and to evaluate the agricultural and environmental implications related to plant nutrient supply and C
sequestration.
METHODOLOGY
In October, 2008, we started a field plot experiment at “La Poveda” experimental farm (Center of Environmental Sciences, Spanish Research Council, Spanish acronym
CCMA-CSIC) located in Arganda del Rey (Madrid, Spain). The experiment was set up as a randomized complete block design with four replicates in a split plot treatment
arrangement. The main plot treatments are (1) an unamended control, (2) a mineral fertilization, and (3) municipal solid waste compost, (4) composted sewage sludge, and (5)
thermally-dried sewage sludge applied at a rate of 30 t ha-1. The subplot treatments are (1) only one application of organic amendment made at the beginning of the
experiment and (2) annually consecutive additions. Physical fractionation techniques based on density and size characteristics to divide organic matter according to location
in soil (organic particles material freely located between and within soil macroaggregates, fine organic particles protected within stable microaggregates, and silt- and clayassociated organic matter) will be combined with advanced physicochemical, chemical, isotopic, microbiological, and modeling approaches.
MUNICIPAL SOLID WASTE
COMPOST (MC)
44 m
2m
2m
1.2 m
COMPOSTED SEWAGE SLUDGE
(CS)
32 m
15 m
6.9 m
3m
Control (unamended)
THERMALLY-DRIED SEWAGE
SLUDGE (TS)
Mineral fertilization
-1
-1
-1
-1
-1
-1
30 t ha y of MC applied the first year only or every year
30 t ha y of CS applied the first year only or every year
30 t ha y of TS applied the first year only or every year
Unamended plots
ACKNOWLEDGMENTS
This project is being funded by the Directorate-General for Universities and Research of the Autonomous Community of Madrid (DGUI-CAM) and the Spanish Research
Council (CSIC) through the program “Grants for Creation and Consolidation of CSIC Research Groups in the CAM” (CCG08-CSIC/AMB-3439).