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Deep ploughing mineral soils for SOC sequestrationViridiana Alcantara Cervantes1,3

Axel Don1, Reinhard Well1, Florian Schneider1, Rolf Nieder2

1Thnen Institute of Climate-Smart Agriculture, Germany2Technical University of Brunswick, Germany3FAO

March 22nd 2017 Global Symposium on Soil Organic Carbon

Alcantara Deep ploughing for SOC sequestration222 March 2017Subsoils store >50% of global SOC stocks in 0-100 cm depth (Batjes 2014, EJSS)Most SOC sequestration measures focus on topsoilsSOC storage potential of subsoils is large:Free mineral surfaces + low carbon concentrations (Beare et al. 2014, BGC; Rasse et al. 2005, Plant & Soil)High radiocarbon ages (Gleixner 2013, Ecol. Research; Mathieu et al. 2015, GCB)Burial of surface soils can lead to net accumulation of SOC (Van Oost et al. 2012, PNAS; Hoffmann et al. 2013, Gl. Biogeochem. Cycles)

First study of deep ploughing (active topsoil burial) in the context of SOC sequestration

Alcantara Deep ploughing for SOC sequestration322 March 2017Deep ploughing:Land improvementFull-inversion tillage> 60 cmPerformed only once

Profile modification:Alternating diagonal stripes of topsoil and subsoil material Establishment of new topsoil

Deep-ploughed Dystric Cambisol(Essemhle, NW Germany)

Alcantara Deep ploughing for SOC sequestration422 March 2017

What is the effect of deep ploughing on SOC stocks?Alcantara Deep ploughing for SOC sequestration522 March 2017

Deep ploughed subplotReference subplot20 m

40 m20 m40 m

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx20 corespitpit15 cores

One experimental field (deep ploughing 35-50 years ago)35 soil cores down to 100 cm depth 5 composite samples per subplot5 sandy and 5 loamy cropland experimental field sites in Germany

Alcantara Deep ploughing for SOC sequestration622 March 2017

On average: 42 13 Mg ha-1 higher SOC stocks in deep ploughed subplotsWilcoxon rank sum test: *p < 0.05, **p