Suitability of gasification biochar as a renewable phosphorus fertilizer

Transcription

1 Suitability of gasification biochar as a renewable phosphorus fertilizer Dorette Müller-Stöver, Mette Grønlund, Iver Jakobsen and Henrik Hauggaard-Nielsen

2 Fuel flexible, efficient and sustainable lowtemperature gasification Tobias Thomsen 2 DTU Chemical Engineering, Technical University of Denmark

3 Thermal conversion (lowtemperature gasification) Identification of valuable waste streams (straw, manure, sludge, industrial waste) Char containing: plant nutrients (K,P, Mg) carbon (up to 50 %) PAH, heavy metals? DONG Energy feedback Lab, greenhouse, and field experiments Soil-applied char is tested for: fertilizer value soil carbon sequestration 3 DTU Chemical Engineering, Technical University of Denmark

4 shoot P uptake (mg/pot) shoot dry matter (g/pot) First screening of different gasification biochar/ash materials for their P fertilization effect Mineral fertilizer Plant growth Straw biochar Barley growth at 80 mg P kg -1 soil as straw biochar (right) or KH 2 PO 4 (left) P uptake P applied mg/kg soil 4 DTU Chemical Engineering, Technical University of Denmark

5 Characteristics of chars (ash) used Straw Total C (%) 48 P (%) 0.4 K (%) 7 Mg (%) 0.5 Fe (%) 0.2 Al (%) 0.4 Mn (mg/kg) 109 Mo (mg/kg) 3.2 Zn (mg/kg) 64 ph 12 Sludge Sludge 1 = P chemically precipitated 5 DTU Chemical Engineering, Technical University of Denmark

6 shoot P uptake (mg/pot) shoot dry matter (g/pot) First screening of different gasification biochar/ash materials for their P fertilization effect Mineral fertilizer Straw biochar Sludge ash Plant growth CON SL STR P uptake Barley growth response to ash amendments: CON= control without P SL= sludge ash (230 mg P kg -1 soil) STR = straw ash (160 mg P kg -1 soil) P applied mg/kg soil 6 DTU Chemical Engineering, Technical University of Denmark

7 Shoot dry matter (g/pot) Olsen P/yield Straw biochar Mineral fertilizer Olsen P (mg P/kg dry soil) 7 DTU Chemical Engineering, Technical University of Denmark

8 First conclusions: some gasification biochar materials can increase plant P uptake in pot experiments strong dependency on feedstock used in comparison with mineral P, higher application rates (as total P) are required to achieve the same yield Olsen-P probably not an appropriate soil parameter to predict plant response 8 DTU Chemical Engineering, Technical University of Denmark

9 Plant uptake microbial activity Available organic P root growth Soil solution P ph Available inorganic P extension.psu.edu Stable organic P Stable inorganic P DTU Chemical Engineering, Technical University of Denmark

10 Pot experiment using a 33 P dilution method 10 DTU Chemical Engineering, Technical University of Denmark 13 March 2014

11 Indirect labelling technique Measure P uptake and specific activity labelled P non-labelled P P derived from fertilizer (%P dff ): 100*[1-(SA plant+ fert /SA plant-fert )] DTU Chemical Engineering, Technical University of Denmark

12 Treatments: untreated control mineral P } 80 mg P /kg sludge ash soil (sludge straw biochar 120) 4 weeks incubation 7 weeks growth period DTU Chemical Engineering, Technical University of Denmark Analysis: biomass P uptake SA

13 Plant dry matter (g/pot) Plant dry matter b b a a root shoot 2 0 Co Sludge ash Straw biochar Mineral P 13 DTU Chemical Engineering, Technical University of Denmark

14 P uptake (mg/pot) Distribution of total P taken up P from fertilizer P from soil 13% 46% b 69% c 10 5 a a 0 CO Sludge ash Straw biochar Mineral fertilizer 14 DTU Chemical Engineering, Technical University of Denmark

15 Conclusions plant P uptake from biochar difference in plant P uptake between biochar and mineral fertilizer mainly due to P in biochar (not soil P) lower P availability in biochar to be able to more precisely evaluate the P availability in biochar compared to mineral P, more experiments are needed (different soil type, crop type, soil P availability ) 15 DTU Chemical Engineering, Technical University of Denmark

16 Thanks for your attention! 16 DTU Chemical Engineering, Technical University of Denmark 13 March 2014