SP04: Soil Organic Matter Turnover

Carbon stocks, turnover and nutrient budgets in soil along land-use and climatic gradients


Objectives

This subproject will provide together with our Brazilian counterpart subprojects information about the soil organic carbon (SOC) stocks, as well as the quality and function of SOM, how these parameters are influenced by land use and under changing climate and, finally, identify what innovative management tools can be used to increase C storage in stable SOM pools and to improve SOM and soil quality.

Management recommendations for SOC enrichment are often identically to existing techniques of sustainable land use, e.g. no-tillage, agroforestry, or mulch farming, but verification of- and controlling by SOM pool monitoring are scarce. The same applies for new approaches in soil restoration, e.g. black carbon enrichment (biochar). Crucial step of this subproject is, therefore, the development of an easy-to-use proxy which must be well applicable by extension agents or the farmers themselves.

Our specific objectives are to

(1) determine the native background stocks of N, P, K, Mg, Ca, and S in soil to a depth of 10 m in the native systems (rain forest and Cerrado);

(2) determine the temporal change in C and nutrient stocks using space-for-time substitution along the pioneer front gradient from central Mato Grosso to south Pará to assess the influence of land use on C and nutrient budgets;

(3) analyze the stocks of bulk C and of C in soil fractions differing in function and turnover to determine the influence of land use and soil management on distribution of SOM into different pools (i.e., analysis of the quantity and quality of C storage in soil);

(4) quantify the C turnover in these fractions by a combination of the stable C isotope and the 14C approaches (i.e., analysis of the sustainability vs. vulnerability of C storage in soil as affected by land use and soil management);

(5) assess the influence of climatic change on these parameters along the climatic gradient from central Mato Grosso to south Pará (i.e., analyze the sustainability vs. vulnerability of C storage in soil as affected by climate change); and

(6) parameterize a C and N turnover model (e.g. CANDY, Rühlmann et al. 2006) at plot level and calculate different land-use and climate-change scenarios.

Please see also the Poster of SP 04 presented at the Kick-Off Workshop in Cuiabá, Brazil, 6-9 July 2011

Project Members
Prof. Dr. Georg Guggenberger
Institute for Soil Science, Leibniz University Hannover
Dr. Jens Boy
Institute for Soil Science, Leibniz University Hannover
Prof. Dr. Wolfgang Wilcke
Geographical Institute, University Bern
PhD candidate Simone Hoffmann
Institute for Soil Science, Leibniz University Hannover

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