Biochar: A new GHG emission mitigation strategy?

1. Biochar: A new GHG emission mitigation strategy? HamzeDokoohaki Department of Agronomy Iowa State University

2. 1. Introduction • 2. Introducing Biochar • 2.1 Biochar attributes • 2.2. Capacity of Biochar as new mitigation strategy • 2.2.1 N2O interaction • 2.2.2 CH4 interaction • 2.2.3 CO2 interaction • 3 What is missing • 4. Future work • 5. Conclusion

3. Climate change will significantly impact agriculture by increasing water demand, limiting crop productivity and by reducing water availability. • The anticipated impacts of climate change pose an additional stress on food production systems. • In too many places achievement in production have been associated with management practices that have been degraded the land and water resources Introduction

4. Introduction • On the other hand in the near future we are going to deal with one new problem in addition to increase in population and life style. Global Warming • Even for the same amount of people, we need to incorporate as much adaptive innovation as possible to keep the crop productivity as the same or even higher.

5. Biochar is pyrolyzed organic material intended for soil application. • Pyrolysis is defined as the thermochemical transformation of carbonaceous materials at high temperature under oxygen-limited conditions. • Comprised primarily of condensed aromatic ring clusters with functional groups attached, and inorganic ash Introducing Biochar What is Biochar?

6. To date, the beneficial effects of adding biochar to soil include: • Increased crop productivity, pH and soil moisture retention, improved soil structure, increased nutrient retention, • Decreases in N2O and CH4 emissions, reductions in leaching of inorganic N, adsorption of anthropogenic chemicals such as steroid hormones, and adsorption of heavy metals Introducing Biochar

7. Biochar attributes • Biochars are mostly carbon, and usually have very high C: N ratios on an elemental composition • The pore sizes in biochar are typically in the intermediate range • The high CEC of many biochars is often cited as a potential mechanism to retain NH4+ • Most biochars have a pH >7, and can go as high as pH=11; • Indirect effect on soil phosphorus availability • The BC has an approximate mean residence time (MRT) in the soil from 7 to more than 1000 years.

8. Capacity of Biochar Primary greenhouse gases associated with the agriculture sector are nitrous oxide (N2O) and methane(CH4). Biochar because of its long lasting attribute can be thought as a way to put delay in carbon cycling between atmosphere and biosphere. Soil organic matter get back to atmosphere after less than 2 or 3 years while it’s possible to transform it into biochar (something more stable) in order to keep it buried. biochar because of its nature intervenes in lots of soil processes and it is suggested that it has some suppressive effects on N2O, CH4 and CO2 emission of soil.

9. N2O interaction • Several laboratory studies show N2O emissions to decrease under certain conditions (e.g. Van Zwieten et al.,2010; Stewart et al., 2012). • Field studies by (Zhang et al., 2010; Zhang et al., 2012) showed significant emission reduction when 300 kg N ha-1 was added. • biochar decreased the cumulative N2O emissions from paddy soil significantly by 16.3% - 18.4%, respectively (Liu et al.,2013). • Yanaiet al. (2007) reported an emission reduction of 89% at WFPS of 73%, but then an increase of ~50% at WFPS of 83%, clearly indicating a dramatic shift in production.

10. CH4interaction • CH4 is produced naturally from wetlands and through anthropogenic activity, mainly cultivation of paddy rice. • Wide variations in the rates on CH4 emissions is reported : • Rondon et al. (2006): Application of wood-derived biochar at a rate of 20 t ha−1 remarkably increased the annual methane sink. • Rondon et al. (2005): Observed complete suppression of CH4 emissions from a grass stand. • Liu et al., (2013): Using biochar has shown to reduce the cumulative CH4 emissions from paddy soil significantly by 64.2% - 78.5

11. CH4interaction It appears that amounts of CH4 emissions depend on the soil type, the chemical properties of the biochar, and on the fertilization and water management regimes (Zhang etal., 2010)

12. CO2 interaction • A cobenefitof biochar amendment is a reduction in soil CO2 emissions. • Carbon dioxide (CO2) is being released immediately after application, but could be reduced due to adsorption of dissolved organic carbon (DOC) on its surfaces (Thies and Rillig, 2009). • Under paddy soil biochar reduced the cumulative CO2 emission significantly by 25.3% (Liu et al., 2013).

13. CO2 interaction • In the few long-term studies, biochar suppress or have negligible effects on soil CO2 emissions, (Wardle et al., 2008; Spokas, 2012). • Over 2 years in the field, soil CO2 emissions were suppressed by 33% on average and net soil CO2 (Case et al.,2014). • Sustainable global implementation of biochar can potentially off set a maximum of 12 % of current anthropogenic CO2

14. What is missing • Perhaps the biggest challenge of using biochar is economic. • There are other and sometimes very high-value alternative uses for chars. • We may need to focus on co-products of biochar such as heat or electricity

15. What is missing • Biochar, like charcoal, is a flammable solid and as such, requires careful handling. • Based on UN Hazardous Goods classification system, chars are Class 4.2 Spontaneously Combustible Materials. • For storage, biochars should be kept in cool, dry places--preferably in air-tight containers—away from heat and ignition sources.

16. What is missing • There are few cases, however, where biochar may produce a negative effect on crop. • 1- When biochar is very alkaline (pH values around 10) - high-ash biochars are used • 2-Contamination of the soil with • heavy metals or other toxins from • applying biochar made from • inappropriate feedstocks

17. Future Work • There are still a lot of uncertainties associated with biochar • BUT • the idea of using biochar is some kind promising. • We need to know more about biochar especially about its interaction with carbon and nitrogen in soil. • There is a vital need to fully document the production style, biomass conditions, and pyrolysis conditions of the biochar production

18. Conclusion • It appears biochar may be useful as mitigation strategy but its performance is highly dependant on the soil type, the chemical properties of the biochar, and on the fertilization and water management.