Biochar: A Potential Soil Organic Amendment in Tea K M Mohotti 1, G P Gunaratne 1, A J Mohotti 2 and U R Sangakkara 2 1 Tea Research Institute 2 University of Peradeniya Outline Introduction to Biochar Soil Organic Amendments Definition Production/Preparation Benefits in Agriculture Research Experiences FAQs Preliminary Research in Tea Way Forward 1
Incorporation of Soil Organic Amendments (SOA) Materials: Compost, tea waste, spent tea, animal waste, prunings, green manure, neem poonac, Ash Benefits: Soil fertility and organic matter status Biological, chemical and physical properties Soil amelioration Suppression of pathogens Practical limitations: Production Availability in large required volumes Transportation Application and handling Cost The Carbon Family Feed stock Production Charcoal Activated Carbon Biochar Hard wood Saw dust + Binding agents Slow Pyrolysis; Kiln Coconut shells Peat Coal Pyrolysis @ 600-900 C + Activated @250 C OR Chemically impregnated and cooked @ 400-900 C Kiln Agro- or Forest waste Other organic materials Slow Pyrolysis; Kiln; Gasification Qualities Burnability Adsorption Adsorption CEC Sequestration Common uses Fuel for cooking Filtration Odor control Remediation Binding agents Cost Medium Very high High Carbon foot print Soil amendment Remediation Filtration Binding agents Carbon Neutral Carbon Positive Carbon Negative 2
Biochar Biochar is a solid carbonaceous / high cellulose material obtained from pyrolysis of biomass in the presence of little or no oxygen Biochar is a proven soil organic amendment which is a concentrated carbon rich source with unique soil improvement characteristics and largely resistant to decomposition Hence called as Dark Gold Pyrolysis Feedstock is heated to high temperatures (over 450 0 C) under controlled conditions. The biochar-making process is called pyrolysis when no oxygen is present and gasification when low amounts of oxygen are used. The gas or oil produced from heating feedstock can be used as clean energy. The carbon left behind is biochar. Final product appears in different grades as powder and in nugget sizes. 3
Slashing & Burning in Chena Cultivation Partially Burnt Paddy Husk 4
Optimal Temperature for Biochar Production Source: Lehmann et al. (2007) 5
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Biochar Products Powder Granules Nuggets Unique Characteristics of Biochar The porous, crystalline biochar structure adsorbs bio-oils, nitrogen, phosphorus, other nutrients from feedstock Source: Saran Sohi Edinburgh University, UK 7
Unique Characteristics of Biochar: contd. 1. Very high surface area and the micropores provide extremely higher opportunities for soil microorganisms, nutrients and water 2. While leaching and volatilization inhibited, nutrients are bioavailable to plants Source: Robert Brown, Iowa State University, USA Benefits of Biochar in Agriculture Improve Water Holding Capacity Nutrient retention Reduce methane & NO emissions Capture & store carbon Increase soil carbon pool Improve soil microbial activity Recalcitrant to decomposition Absorb toxic compounds (Lehmann et al., 2003) 8
Biochar and Crop Yields Crop Country Reference Maize Ghana Oguntunde et al. (2004) Soybean Japan Kishimoto & Sugiura (1985) Sugi trees Japan Kishimoto & Sugiura (1985) Bauhinia trees Africa Chidumayo (1994) Beans USA Rondon et al. (2007) Pea India Iswaran et al. (1980) Mung bean India Iswaran et al. (1980) Tea Sri Lanka Krishnaratne (2012) Rice Laos Asai et al. (2010) Rubber Sri Lanka Dharmakeerthi et al. (2010) Long Term Field Experiences with Biochar 9
Long Term Field Experiences with Biochar contd. Biochar posses soil improvement properties and as a valuable tool to build soil, conserve water, retain nutrients, adsorb contaminants and sequester carbon in agricultural industries and impacts on crop productivity. Overall Objectives of Preliminary Studies at TRI 1. Production of Biochar from local feed materials. 2. Determination of their characteristics. 3. Evaluation of their impacts on soil biological, chemical and physical properties and early growth of tea. 4. Estimation of nitrogen retention and carbofuran absorbance in Biochar incorporated tea soils. 5. Study change of organic carbon, Cation Exchange Capacity, ph, available K, moisture content and microbial activity in Biochar incorporated tea soils as compared with compost, chena charcol, activated carbon and Natural zeolite. 6. Effect of Biochar on root growth of tea. 10
Study 1: Evaluation of Different Biochar from Various Sources Sources / Feed Stock Eucalyptus Gliricidia Pinus Caliandra Eucalyptus Jungle tree species Coconut shell Paddy husk Caliandra Pinus Gliricidia Paddy husk Coconut shell 11
Particle Size of Different Biochar Sources ( 100) Biochar Gliricidia Biochar Pinus Biochar Caliandra Biochar Jungle tree species Biochar Eucalyptus Biochar Coconut shell Biochar Paddy husk Biochar Eucalyptus 12
Study 2: Effect of Different Biochar Sources on Early Growth of Tea Material Biochar 1 Biochar 2 Chena charcoal Activated carbon Natural zeolite Particle size 3mm 2.5 cm 2.5 cm powder powder Growth of Tea under Glass House Conditions Soil Amendment Plant height (cm) No. of leaves Leaf area (cm 2 ) Root length (cm) Biochar 1 41 a 11.5 a 269.3 a 19.3 ab Biochar 2 41.9 a 16 a 281.8 a 17.15 b Chena charcoal 41.4 a 21 a 387.5 a 24.1 ab Activated carbon 41.7 a 9.5 a 294.3 a 18.7 ab Natural zeolite 43.7 a 16.5 a 400.8 a 25.5 a Untreated 43 a 15 a 339 a 22 ab 13
Growth of Tea under Controlled Conditions (27 C) Soil amendment Plant height (cm) Stem diameter (mm) No. of leaves Leaf area (cm 2 ) Biochar 1 40.65 a 4.7 a 11.5 a 258.7 a Biochar 2 42.15 a 3.44 a 12 a 271.7 a Chena charcoal 42.9 a 4.12 a 14.5 a 310 a Activated carbon 38.95 a 3.95 a 14.5 a 317 a Natural zeolite 41.2 a 3.52 a 9.5 a 292.2 a Untreated 38.8 a 3.7 a 12.5 a 303.5 a Soil Parameters in Amended Tea Soils Soil Amendment EC ( S) P ( g/g soil) K (mg/100g soil) Ca (mg/ 100g soil) Biochar 1 270.9 a 2.71 a 16.56 ab 69.64 b Biochar 2 287 a 1.09 a 14.24 b 69.64 b Chena charcoal 208.3 a 1.51 a 16.48 ab 69.64 b Activated carbon 383.5 a 2.11 a 18.65 ab 69.64 b Natural zeolite 161.8 a 1.33 a 15.89 ab 95 a Untreated 276 a 1.53 a 21.5 a 69.64 b 14
Nitrogen retention / (%) 27/07/2016 Study 3: Evaluation of Adsorption of Agrochemicals in Tea Soils Urea solution / Carbofuran 1. Biochar 1 2. Biochar 2 3. Charcoal 4. Control 45 cm Bioassays Leachate a. Nitrogen Retention 102 100 98 96 a b b 94 92 90 c 88 86 84 82 Biochar 1 + Urea Biochar 2 + Urea Charcoal + Urea Urea only (control) Biochar 1 (5-8mm) showed significantly (p>0.05) higher nitrogen retention 15
Mortality (%) 27/07/2016 b. Pesticide Absorbance 100 90 80 a 70 60 50 40 b b 30 20 10 0 c d Biochar 1 (5-8mm) showed significantly (p>0.05) higher pesticide absorption Study 4: Impacts on Root Growth of Tea Biochar 1 Biochar 2 16
Total Root Length (cm) Amount of CO₂ (mg/ g root/day) 27/07/2016 a. Root Growth and Respiration Total Root Length 60 55 50 45 40 35 30 0.012 0.01 0.008 0.006 0.004 0.002 0 Root Respiration P > 0.05 P > 0.05 Biochar 1 Untreated Biochar 2 17
ph Total Organic C % Available K (mg/kg) CEC (meq/100 g soil) 27/07/2016 b. Soil Chemical Properties 5 4.9 4.8 4.7 4.6 4.5 4.4 4.3 4.2 4.1 4 b ph c a d e 250 200 150 100 50 0 Available K a b b a c P > 0.05 P > 0.05 Soil Chemical Properties: contd. 3 2.5 Total Organic Carbon 25 20 CEC 2 1.5 1 0.5 0 e 15 10 5 0 P > 0.05 P > 0.05 18
Moisture Content (%) Green leaf kg /ha Aug-12 Sep-12 Oct-12 Nov-12 Dec-12 Jan-13 Feb-13 Mar-13 Apr-13 May-13 Jun-13 Jul-13 Aug-13 Sep-13 Oct-13 Nov-13 Dec-13 Amount of CO₂ ( mg/10g soil/day) Jan-14 Feb-14 Mar-14 Apr-14 May-14 Jun-14 Jul-14 Aug-14 Sep-14 Oct-14 Nov-14 Dec-14 Jan-15 Feb-15 Mar-15 Apr-15 May-15 27/07/2016 Soil Chemical Properties: contd. 44 42 40 38 36 34 32 30 Moisture Content 0.0007 0.0006 0.0005 0.0004 0.0003 0.0002 0.0001 0 Soil Respiration P > 0.05 P > 0.05 Local Experiences 1: Rilhena Estate, Rakwana 1400 Yield (Mean Green Leaf kg/ha) 1200 1000 800 600 400 200 Biochar Applied Field Conventional Field 0 Pruning & Biochar Application Field 2006 TRI 2025 4 ha 19
Jan-13 Mar-13 May-13 Jul-13 Sep-13 Nov-13 Jan-14 Mar-14 May-14 Jul-14 Sep-14 27/07/2016 Local Experiences 2: Harington Estate, Kotagala 140 120 Yield (Mean Made Tea kg/ha) 100 80 60 40 Bio char applied field Conventional field 20 0 Biochar Application Field No. 1 TRI 2025 2 ha Last pruned: Oct. 2010 350 g Bio char + 300 g Compost / Bush Summary and Potentials Little evidences of short term benefits of soil and plant growth Feasibility as a potential Soil organic amendment Moisture holding capacity improved Nitrogen retention showed Pesticide losses lowered Root growth enhanced Root rhizosphere strengthened Soil microbial activity enhanced Soil carbon improved Paddy husk and coconut shell sources proven to be promising than Gliricedia 20
Way Forward Determination of application rates Testing application methods: mixing with compost, soil, sand Determination of application time: nursery, planting hole, post prune, rehabilitation Assessment of long term impacts: yield, cost benefits and added advantages over SOA Carbon sequestration and climate change mitigation potentials Opportunities to couple with soil microbial inoculations, biofertliliser applications, soil nutrients and pesticides Monitoring of field data Production of Biochar using appropriate local feed stocks Long term investments negotiating cost factor Thank you 21