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Fate of Plant Residues in Soil Organic Matter Pools under Contrast Land Use as Evaluated by Two Tracer Techniques

AvH, INI 1128575 STP-2

From 04/2008 to 09/2011

Principal Investigator: Yakov Kuzyakov

Soil C sequestration through changes in land use and management is one of the important strategies to mitigate the global greenhouse effect. Plant residue is the primary source of C formation and sequestration in soil. The relative contribution of residues depends upon composition and decomposability of litter which is a function of lad use and management. The present project is conceived with objective to evaluate the fate of plant residue in soil C influenced by different land-use management practices. Ultimate aim to sketch policy for appropriate management practices, which would facilitate enrichment of C stock in soils for maintaining soil health and fertility as well as mitigation of global warming by C sequestration. Management practices like intensity of tilling and no tillage have a definite effect on SOC stock; it would be considered as pertinent management practice for residue derived C-turnover. To fulfil the objective as stated, representative soil samples will be collected under various land covers/uses and management practices and analysed for important physico chemical properties e.g. pH, CEC, clay content, bulk density, soil water storage, and soil porosity are the important soil physical parameters which influences C load in soil. Different pools of C viz. total SOC (Ctot), Water stable aggregates, labile fractions of oxidisable organic carbon etc. will be studied to know the C stock and its distribution in soil. Impact of added plant residue on C sequestration and C dynamics of plant residues decomposition in contrast land use will be analyzed and quantified by using 14C labelled plant residues as well as 13C natural abundance and allow for differentiation between residues-derived carbon and native SOC. Labeled microbial biomass C and mineralizable C, acetone exactable reside, 14C and d13C in CO2 and in SOM pool will be measured that may provide precise estimates of residues decomposition rates and contribution in soil organic C. Microbial biomass carbon (Cmic) and mineralizable carbon (Cmin) measured as early indicators of future trends in total SOM as it provides a good measure of labile organic matter because it directly reflects recent soil organic matter turnover. Data on biomass productivity will also be collected from those sites. Results would help us to know the relative efficiency of different land use managements for organic C enrichment or depletion in soils.

last modified 2011-10-03