THE THIRD WORLD CONFERENCE OF WASWAC

1. THE THIRD WORLD CONFERENCE OF WASWAC August 22-26, 2016Belgrade/ Serbia SANRU Black carbon (Charcoal or biochar) application as a sustainable management approach in temperate region: a lesson from historical charcoal production sites in beech forest of Northern Iran Authors: Mostafa Emadi, Fatemeh Faghih, Fardin Sadeghzadeh, Mohammad Ali Bahmanyar Soil Science Department, Sari University of Agricultural Sciences and Natural Resources, Sari, IRAN Presenter: Prof. Hossein Ghadiri Environmental Futures Research Institute, Griffith University, Brisbane, QLD, AUSTRALIA

2. Introduction • The black carbon, also called charcoal and biochar, considered important in soil science since the identification of the Amazonian dark soils “Terras Pretas de Indio”. • The dark color of Terra preta soils comes from the high content of stable charcoal or pyrogenic C (biochar). • These soils have higher pH, soil organic C, cation exchange capacity, phosphorus, calcium, magnesium, and are less susceptible to leaching. This made it a resource for sustainable agricultural practice in tropical regions with nutrient-poor soils.

3. Introduction • The clear benefits in the Terra preta soils of the Amazon will not necessarily occur in other regions. • The performance of this system and the long-term benefits of charcoal presence in temperate regions are increasingly being questioned. • The evidences showing the long-term presence of charcoal/biochar on soil properties in temperate regions like Northern Iran is highly crucial for better understanding of the implications of large scale application of charcoal/biochars into the soilsboth for improving soil quality and carbon sequestration

4. Objectives The main objective of this study was to investigate the effects of historical charcoal enrichment on some soil physical, chemical and biological properties in the temperate zone of Northern Iran.

5. Sampling site • Composite soil samples were taken from 0-20 and 20-40 cm soil depths in and out of charcoal-enriched soils surrounding the historical charcoal production sites, abandoned for more than 120 years, in temperate deciduous forests of Mazandaran province, Northern Iran. The mean annual precipitations is 780 mm. The soil moisture and temperature regime classes are udic and thermic, respectively. Fig. 1. The location of the study area and the sampling site

6. Fig. 2. The soil profile of the Terra preta-like soil (A) and the adjacent forest reference soil (B). The charcoal was incorporated into soils up to 40 cm soil depth.

7. Soil Analysis The following soil properties were determined in totally 24 undisturbed and 24 disturbed soil samples. Soil chemical properties • pH • Electrical conductivity (EC) • Total nitrogen (TN) • Available phosphorus (Av-P) • Exchangeable bases (Ca++, Mg++, K+ and Na+) • Cation exchange capacity (CEC) • Total organic carbon content (TOC) • Black carbon (BC) using the benzene polycarboxylic acid method (Brodowski et al., 2005) • Natural soil organic carbon (NSOC) NSOC=TOC-BC • Soil organic carbon density (SOCD) (kg m−2) • Calcium carbonate equivalent, (CCE ) • Dissolved organic matter (DOM) Soil Physical properties • Bulk density (g cm−3) • Water content at the field capacity (FC), -33 kPa, • Water content at permanent wilting point (PWP), at -1500 kPa, • Available water capacity (AWC)=FC-PWP • Saturated hydraulic conductivity (Ks) Soil Biological property • Soil microbial respiration (MR)

9. Long-term effects of charcoal on soil carbon The TOC contents were about 288% and 268% higher in 0-20 cm and 20-40 cm soil depths in Terra preta-like soils. NSOC contents were about 247 and 126 % greater in charcoal-enriched soils. This could attributed to the high porosity and surface area of the charcoal that stabilize other fresh input sources of OC in soil through adsorption processes providing a pool of C that is resistant to mineralization.

10. Long-term effects of charcoal on soil chemical properties Most notably, Terra preta-like (biochar added) soils had significantly higher pH, CEC, TN, P, Zn, Fe and Mn and exchangeable Ca++, Mg++, K+, Na+ and CCE than adjacent reference soils, but the latter had significantly higher EC and Cu. The high CEC and nutrient retention in charcoal enriched soils of the study area may be resulted from additional exchange sites provided by the high SOM level and in particular the BC concentration (Liang et al., 2006; Wiedner et al., 2015) and increases of negative surface charge as a consequence of the presence of an abundance of functional groups.

11. Long-term effects of charcoal on soil microbial respiration The soil MR rates were not significantly affected by the presence of aged charcoal. This can be attributed to the sorption of nutrients and available organic C on BC. These results concur with increase of C sequestration and high level of NSOC in the presence of >120 years old charcoal.

12. Long-term effects of charcoal on soil physical properties The charcoal-rich soils had significant lower BD in 0-20 and 20-40 cm soil depth by 12 and 25%, respectively, compared with adjacent forest soils. At 0-20 cm soil depth, the FC, PWP and AWC and Ks were higher about 16%, 8.7%, 34%, and 51 %, respectively, in charcoal-rich soils. This could be attributed to the retaining water in charcoal structure, aggregation and clay flocculation using substituting the monovalent cations (Na+ and K+) on exchange sites of clay particles by divalent cations (such as Ca++ and Mg++).

13. Conclusion • The charcoal-enriched soils in temperate zone of Northern Iran significantly and positively affected soil properties compared to the adjacent forest soils. • The former charcoal additions elevated the soil qualities and carbon storage capacity of temperate soils. • In spite of the elevated nutrient status of the charcoal-enriched soils, the soil microbial respiration is not significantly changed suggesting resistance to microbial degradation of added charcoal thus effective C sequestration

14. Thank you for your attention

15. Long-term effects of charcoal on soil chemical properties Back