Wednesday, 12 September 2018

Rice growing, biochar trial in Thailand

Gordon Hirst has sent me a link to a Facebook page that is recording a 5-year rice growing field trial in Thailand which includes biochar.

The page needs an introduction to set the scene but if you scroll to the start (3 July 2017), you can review progress via video posts and trial records...

"A field experiment using both a biochar fertilizer/ soil enhancement and SRI (system of rice intensification) to attempt to double the yield of a working farm, from 500 Kg/Rai to 1000 Kg/Rai. The farm is paddy rice farm located in Nakhon Ratchasima province ten Rai (1.6 Ha). The experiment will last for five years"

Friday, 7 September 2018

Biochar social enterprise in Thailand (part 3 of 5)

Cool the Climate, Clean the Environment, Improve Public Health, Reduce Rural Poverty with Small-Scale Biochar - Part 3

President, Board of Directors at Warm Heart Worldwide, Inc. 14 articles

Sows’ Ears into Silk Purses

On Sun, Sep 2, 2018 at 8:42 PM '' [biochar] <> wrote:
  Here is the 3rd article in the 5 part series, this one focused on how a small-scale biochar social enterprise business model can (and does) work.

For those of you who are frustrated with the drip feeding of articles, this link will take you to a downloadable PDF of all five: 

SOC decline in tropical plantation soil - new evidence

This new report should be of interest to all plantation industries and forest managers... and should support more interest in biochar production and application opportunities...

Changes in soil organic carbon stocks after conversion from forest to oil palm plantations in Malaysian Borneo


"The continuous rise in the global demand for palm oil has resulted in large-scale expansion of industrial oil palm plantations - largely at the expense of primary and secondary forests. The potentially negative environmental impacts of these conversions have given rise to closer scrutiny. However, empirical data on the effects of conversion of forests to industrial oil palm plantations on soil organic carbon (SOC) stocks is scarce and patchy. We evaluated the changes in SOC stocks after conversion of tropical forest into oil palm plantations over the first and second rotation period in Sarawak, Malaysian Borneo. Soil samples were collected from three age classes of oil palm plantations converted from forest (49, 39 and 29 years ago respectively) with three replicate sites and four adjacent primary forest as reference. In each site under oil palm, the three management zones namely; weeded circle (WC), frond stacks (FS), and between palm (BP) were sampled separately. All soil samples were collected from five soil layers (0–5, 5–15, 15–30, 30-50 and 50-70 cm). Samples were analysed for SOC concentration, soil bulk density, pH and soil texture. Results showed SOC stocks declined by 42 %, 24 % and 18 % after 29, 39 and 49 years of conversion respectively. Significant differences in SOC stocks were found among different management zones in the oil palm plantations, and the trend was similar for all age classes: FS>WC>BP, demonstrating the necessity of considering within-plantation variability when assessing soil C stocks. The largest differences between SOC stocks of the reference forest and converted plantations were found in the topsoil (0-15 cm depth) but differences were also found in the subsoil (> 30 cm). Our results will contribute towards future modelling and life cycle accounting to calculate the carbon debt from the conversion of forest to oil palm plantations."

Biochar project report from Malaysia

Prof. Rob Bachmann from UniKL has kindly shared the following report on some of the biochar work he is currently connected with in Malaysia.

1. Universiti Kuala Lumpur (UniKL) under project leader Dr Nadia Razali has teamed up with MPHTJ, a Melakan municipality, to develop a carbon negative solution for their yard as well as wet market waste. A news video of the signing ceremony is available here:

In our project we aim to convert the brown waste (wood) to biochar testing the flame curtain and retort technology.

The biochar will subsequently be added to the green compost as bulking agent, to immobilise leachate and speed up the composting process. The final mature compost can be used as substitute for inorganic fertilizer in MPHTJ nurseries or sold to third parties such as organic farmers.

2. Another project involved a collaboration between UniKL and Top Fruits Sdn Bhd ( with the aim to convert their orchard waste into a valueable product. Our project concluded that Durian wood biochar produced with the Kon-Tiki earth kiln technology can partially substitute peatmoss in fruit tree nurseries without negatively affecting plant growth and health. Organic fertilizer was not required during the first 3 months. Plant height was found to be the most accurate and yet easy and affordable growth monitoring parameter. For more information please read our paper here:

3. Research collaboration between UniKL and the Malaysian Palm Oil Board (MPOB) focusses on 3 aspects: i) converting oil palm biomass residues to biochar, ii) characterisation and identification as well as iii) application. Our latest publications report on the effect of humic acid coated PKS biochar on NPK adsorption ( as well as effect of pyrolysis temperature and holding time on biochar yield and carbon stability using All Powers Lab Biochar Experiment Kit (BEK) (

4. Collaboration between a local chicken farm and UniKL aims to develop a scale-able solution for their chicken litter (CL) waste that can reduce the smell and fly problem, destroy pathogens and preserve as many nutrients as possible at an affordable price. At present, lab-scale pyrolysis of CL was successfully deployed to stabilise the biomass in the form of biochar. Poultry litter biochar produced at 400°C for 60 min retains all major plant nutrients (P, K, Ca, Mg, S) except for nitrogen (58 ± 15 % retention).

5. Another UniKL project led by Dr Amelia Md Som seeks to develop a solution to ameliorate acid sulfate soils using bio-physico-chemical approach. Biochar is being produced from oil palm fronts with an earth as well as metal Kon-Tiki kiln. Preliminary findings have been presented at and are available in the Proceedings of the 10th International Symposium on Plant-Soil Interactions at Low pH, June 25-28, 2018, Palm Garden Hotel IOI Resort Putrajaya, Malaysia.

Tuesday, 28 August 2018

Thursday, 23 August 2018

Social enterprise in Bali includes biochar

"Believe it or not, cashew shells are an important part of our business. The circular journey of the cashew shells starts at our factory. To power the steaming and drying process of our cashews, we use an innovative gasifier furnace that runs on leftover cashew shells. We then use the resulting biochar as a super carbon-rich fertilizer for our cashew trees and rosella plantations.

Our excess cashew shells we pass on to other small businesses, such as commercial laundries, which use the shells to heat their boilers. While the shells may seem like a simple byproduct with little value compared to the cashews themselves, they’re actually integral to our operations and need to be managed with care.

In 2016, we started to take the “use the whole cashew” idea to the next level. We have ambitious plans to replant Bali’s – and eventually Indonesia’s – cashew trees within the next decade. Part of this plan involves buying old cashew trees from farmers to make space for the new seedlings. We are using the wood chips from these trees to fire our furnaces as well, leaving no part of the cashew – or its tree – unused."

Crop residue burning in Thailand - WarmHeart (part 1of 5)

Dr Michael Shafer's work with biochar from his 'WarmHeart' base in northern Thailand is well reported here (see WarmHeart tag). Michael is kicking off a 5-part report focused on crop residue burning. Below is his announcement on this to the yahoo international biochar discussion group. It is a highly relevant read for those of us interested in solving regional haze issues.
Aug 21 3:04 AM
"I live in North Thailand where smoke from burning  corn and rice fields blocks the sun a couple of months a year. Burning wheat straw smoke closes Delhi every year, too.

Because most of the farmers who burn are poor and small, collecting their crop waste for central processing is uneconomical and their fields are too small, too steep, too rocky to plow, even if they could afford a tractor.

They are so poor, however, that converting their crop waste to biochar makes lots of sense. Establishing village-scale social enterprises to process local biochar into value added products is also not only appealing to farmers but a replicable way to solve the crop waste burning problem where it starts - in small farmers' fields.

This is the first of a five part series in which I make the case for a small-scale biochar social enterprise business model for addressing the problem. The remaining four will appear over the next few weeks.

I would welcome any comments, suggestions, corrections or criticisms."

Dr. D. Michael Shafer
Founder and Director, Warm Heart
61 M.8 T.Maepang A.Phrao 50190 Chiang Mai Thailand

Friday, 13 July 2018

Biochar activities in Thailand

Dennis Enright is a kiwi who travels to Thailand regularly to work with NGO's on biochar and sustainable farming practices. We have collaborated on biochar development in NZ which has included running biochar training workshops in May/June. We also hope to soon collaborate on biochar projects in SEA with other regional NGO's and consultants.

The following report from Dennis is just one of a number of projects he is working on in Thailand. Others include coffee growers and coconut farmers... reports on these projects in the pipeline.

You can Contact Dennis from his NZ website:

Making Biochar from Mulberry Prunings at Khon Kaen, Thailand – June 29th 2018

Dennis Enright (NZ Biochar Ltd)

Mulberry bushes are grown to produce mulberry leaf tea (and for silk worms). During the growing period leaves are regularly picked from the stems and by the end of the growing season most stems are bare of leaves and are about 2-3 metres high. At this time the stems are cut off at about 10 cm from the base, removed, and stacked in piles around the edges of the field until they are dry and can be burnt. The mulberry plant then produces new shoots and the annual cycle continues.

In June of this year GreenNet Cooperative staff and I visited Ban Hin Herb village (Tambon Prayuen, Prayuen District, Khon Kaen) where we used a metal lined Kon-tiki pit kiln to make biochar from Mulberry bush prunings, and then applied some of this biochar to mulberry plants in a simple experiment to evaluate the effects.

I chose a lined Kon-tiki method because on a previous occasion where biochar was made using damp coconut material in a flat bottomed concrete tub, not all the material charred well. This probably happened because in a container with a large flat bottom it is difficult to get a good base of hot char below the newly applied material to help dry it before more charring occurs.

The Kon-tiki pit liner was made at the village using light gauge sheet metal held into shape with wire, both bought locally and costing less than 500 bt in total.

Making biochar with the lined Kon-tiki worked well, even though the prunings were still partially green (about one month old), and the weather was very humid and for a short time near the start of making biochar it rained quite heavily (see photo).

So while there may be other containers that can work, this is the most effective way to make biochar (refer to research work of Schmidt H P and Taylor P)

Also mulberry prunings were easily turned into biochar that was quite soft and had a very noticeable soapy feel to it.

Some of this biochar was then primed with a slurry of chicken manure/rice husks and used in an experiment. The treatments were; 5 litres of primed biochar per plant (place in a circle - diameter of 30 cm), and 5 litres of chicken slurry only.

These treatments were applied to plants in a single row in the following order starting at plant 7 from the road side:

Plant 7 primed biochar, plant 8 no treatment, plant 9 chicken slurry, plant 10 no treatment, Plant 11 primed biochar, plant 12 no treatment, plant 13 chicken slurry, plant 14 no treatment, Plant 15 primed biochar, plant 16 no treatment, plant 17 chicken slurry, plant 18 no treatment (see photos)

The soil here is sand with very low amounts of organic matter. This experiment is situated on an organic farm and we are interested in determining if biochar can increase the effectiveness of nutrients applied in the usual organic fertilisers such as compost that the farmers apply. If treatment effects become apparent, then assessments can be done using a scientifically acceptable visual scoring procedure and the results statistically analysed.

RFP for biochar consultants in Vietnam

"Rikolto in Vietnam (previously VECO Vietnam) is a member of Rikolto, an international NGO with its International Office in Leuven, Belgium. Rikolto’s mission is to enable and support smallholder farmers to take up their role in rural poverty alleviation and to contribute to feeding a growing world population in a sustainable way. Rikolto is currently implementing the 2017-2021 programme “Supporting Inclusive and Sustainable Agricultural Value Chain Development Benefiting Smallholder Farmers in Vietnam” with a focus on vegetable and rice value chains.

In April 2018, Rikolto started implementing the project “Reducing Greenhouse Gas Emissions from Rice Production in An Giang Province, Vietnam, through Alternate Wetting and Drying and Biochar Production”. This project is a first step to making our target rice value chains more environmentally-friendly and climate-smart. As part of this project, we are looking for a (team of) consultant(s) to assess the feasibility of transforming rice waste into biochar and market it."

Thursday, 12 July 2018

International Biochar Seminar, Indonesia

I received a late invite to "Biochar for Sustainable Soils", hosted by Bogor Agricultural University, about 60km south of Jakarta. The line up included quite a few international stars of the biochar world that I've met before at various conferences and workshops: Johannes Lehmann; Stephen Joseph; Annette Cowie; Lukas Van Zwieten; Gerard Cornelissen; Ruy Korscha.

You can click on the image adjacent for a better view of the program.

The event was based around the completion of Biochar for Sustainable Soils (B4SS), 4-year, a multi-million dollar international program (see B4SS label for other posts). It was attended by ~140, mainly from Indonesian agriculture and research community but included representatives from other participating B4SS countries and Malaysia.

The presentations should be available for download in the future... I'll post on this when they come available.

Tuesday, 12 June 2018

Biochar Malaysia Ass. AGM

My thanks to Dr Sieng-Huat Kong from University College of Technology Sarawak for the following report...

4th BMA Annual General Meeting and Biochar Technology Workshop 2018

The AGM was held on 14th May 2018 at Faculty of Engineering, Universiti Putra Malaysia (UPM). Prior to the commencing of AGM, all the 60 participants were brought to visit the biomass microwave carbonizer pilot plant located inside UPM, which is the collaborative work between UPM and Pakar Go Green Sdn Bhd. The plant can process 250 kg/hour of feedstock (oil palm biomass, coconut shell, bamboo, etc) in batch process and returns up to 50% yield on biochar. Besides, bio-oil is also collected for further research as value-added products compared to biochar as the main product solely.

After the visit and on-site discussion with Pakar Go Green personnel, participants were invited back to the workshop in the faculty with two speakers sharing on their experiences in the industry and academic research in terms of the technology and application of biochar. The 4th AGM commenced right after the workshop, started with the report from previous AGM by the committee members. New management committee for session 2018/2019 was formed with Assoc. Prof. Dr. Mohamad Amran bin Mohd Salleh and Prof. Datin Dr. Rosenani binti Abu Bakar as President and Vice President respectively. More discussions and works proposal were carried out throughout the one hour plus meeting with the aim to contribute positively towards the community, especially the agriculture sector.

Friday, 18 May 2018

Recently Published Biochar-related Resources (May 2018)

Recently Published Biochar-related Resources (May 2018)
May 2018
Robert Gillett , Editor
Papers in this list are from last month’s new ‘biochar’ entries in Google Scholar. Quotes are from the papers, which are accessible through the links provided. These have been extracted by IBI Newsletter Editor Robert W. Gillett to keep the length of this addendum manageable, yet informative enough to prompt further investigation by readers. Emphasis was placed on highlighting new findings leading to practical application, but with the expectation that decisions will be informed by accessing the full publication.

URLs followed by the padlock symbol link to open access articles.

Monday, 14 May 2018

IBI Biochar Study Tour - Austria | 18-21 June 2018

IBI Biochar Study Tour - Austria | International Biochar Initiative

"IBI is excited to announce our second Biochar Study Tour to be held in Austria from June 18-21, 2018.  We are collaborating with Gerald Dunst, CEO of Sonnenerde and Gerhard Soja from the Austrian Institute of Technology; we have been working towards creating an educational and inspiring event.  We are hard at work on the agenda at this stage but wanted to share the overall themes and tours that will be included so that those interested could make their travel reservations early.  Space is limited, so reserve your spot now!" ...

Friday, 13 April 2018

Biochar Webinar - USA

Agenda - Biomass Magazine's Webinar Series

Biomass Carbonization & Torrefaction Summit

This all day webinar features biochar in 2 of the 4 sessions and has an powerful lineup:

9:10 am – 10:40 am How Biochar Production Can Perfectly Complement Heat and Power Production
Moderator: Anna Simet, Editor, Biomass Magazine
  • Tom Miles, Biomass Energy Engineering Consultant, T.R. Miles Technical Consulting
    Overview: U.S. Biochar Initiative, Oregon
  • Jonah Levine, Development Manager, Confluence Energy/Biochar Solutions Inc.
    Biochar and Thermal Energy Production; Product Utilization and Market Examples
  • Greg Stangl, CEO, Phoenix Energy
    Biochar and the Power of ‘And’  
3:30 pm – 5:00 pm Where Biochar is Adding Real Value and Finding Marketplace Traction as a Result
Moderator: Anna Simet, Editor, Biomass Magazine

  • Kelby Fite, VP & Director of Research, Bartlett Tree Experts
    Adding Biochar in the Soil Amelioration Process: An Arborist’s Perspective
  • Mark Highland, President, The Organic Mechanics Soil Company
    Adding Value by Using Biochar Soil Amendments in Custom Engineered Soils
  • James Murphy, President/Owner, Waste To Energy Inc.
    Building Markets through Dependability and Consistency of Products
 If you are chasing a commercial future in biochar or torrefaction, maybe the USD150 will be a good investment.

Sunday, 8 April 2018

The Great Change: Just One Word: Bioplastics

The Great Change: Just One Word: Bioplastics: "Any carbon that does not go back to the atmosphere can just chill. It can be a building or a bicycle, it doesn’t matter. Just c...

I've got Albert's blog listed (bottom, right) but I'm pointing this latest post out for all the folks I know who are into the biochar composite future...

Friday, 6 April 2018

Biochar research from Vietnam - full PDF

Application of Biochar from coconut shells to different soils in Thua Thien Hue province, Vietnam

Tran Thi Tu(1), Morihiro Maeda(2), Le Van Thang(1), Nguyen Dang Hai(1), Tran Dang Bao Thuyen(1)
1) Institute of Resources, Environment and Biotechnology - Hue University, Vietnam
2) Graduate School of Environmental and Life Science, Okayama University, Japan

"We examined the effect of biochar application to different soils on crop growth, phosphorus and nitrogen balances under greenhouse conditions in Thua Thien Hue Province, Vietnam. Results showed that : (1) Komatsuna growth in sandy soil less than clay and organic soils. Biochar improved crop yield in clay and organic soils, but it did not improve in sandy soil. (2) Biochar increased P and N uptake in leaves and roots in clay and organic soils. (3) Biochar reduced P leaching; furthermore biochar reduced TN leaching in organic soil. Besides, biochar reduced NO3-N leaching in clay and organic soils. We further study the N dynamics in soil treated with biochar materials."

Thursday, 29 March 2018

Elephant 'smoking' footage baffles experts

Apparently this elephant does not like charcoal too alkali, so can't be for acid stomach upset!

I hear that elephant dung pollution is a serious issue in Thai tourist traps. Maybe someone needs to start biochar supplementary feed program and dung composting with biochar. Every tourist should be required to take a bag home.

Monday, 26 March 2018

Japan biochar research in tea

Returning Tea Pruning Residue and Its Biochar Had a Contrasting Effect on Soil N2O and CO2 Emissions from Tea Plantation Soil

 More research on tea growing with biochar... this time from Japan. Check out the "tea" tag for more posts on tea.

"...Our results suggest that converting pruning residue to biochar and its addition to soil has the potential to mitigate soil N2O emissions from tea plantation."

Our dying soils: The invisible crisis under our feet

Our dying soils: The invisible crisis under our feet

No mention of biochar here... a sad omission for this important subject.
"The U.S. Biochar Initiative is preparing for Biochar 2018, August 20-23, in Wilmington, Delaware. Keynote speakers will include Dr. David Montgomery, who's most recent book is Growing a Revolution: Bringing our Soil Back to Life, ..."

Monday, 5 March 2018

Saturday, 3 March 2018

Biochar & waste management project - Malacca, Malaysia

Prof. Robert Bachmann from UniKL MICET has kindly shared news on the announcement of a new collaborative project with their local council:

Friday, 23 February 2018

Willie Smits - Borneo update

Dr Thomas Goreau, a climate and coastal restoration scientist, has been to visit Dr Willie Smits in Borneo. I first covered Willie Smits work way back in 2010 (see WillieSmits label) and have had some positive dialogue since on biochar and related issues. Dr Goreau has come back with warm praise and the following report...

I've embedded the 2nd YouTube, as it focuses more on biochar production (Adams retort) but the first video is also great... focusing on sugar palm as a sustainable, community based tropical industry.

Sunday, 18 February 2018

Biochar research from Papua New Guinea

Great to see biochar research coming from Papua New Guinea...

Effects of biochar, urea and their co-application on the nitrogen mineralization in soil and growth of Chinese cabbage crop

Ruth Baiga and Rajashekhar Rao BK*

Department of Agriculture
The Papua New Guinea University of Technology
Private Mail Bag, Lae 411
Morobe Province, Papua New Guinea
Tel: +675 4734464, Fax: +675 4734477

* Dr. Rajashekhar Rao B.K., E-mail:

Experiments were conducted to study the influence of biochar material on N mineralization pattern from the soil applications of kunai grass (Imperata cylindrica) biochar (at 0 and 10 t ha-1) and laboratory grade urea (0, 200 and 500 kg N ha-1) and their co-application to an acid soil. The results of incubation study showed that biochar only treatment and co-application with urea at 200 kg N ha-1 could impede transformation of urea to NH4+-N. Soil application of biochar together with urea 500 kg N ha-1 produced the highest NO3--N and mineral N concentrations in the soil over 90 days. In a parallel study performed under greenhouse conditions, Chinese cabbage (Brassica rapa L. ssp. chinensis L.) crop showed highest marketable fresh weight, N uptake and N use efficiency in soil treated with biochar along with urea at 500 kg N ha-1. However, soil incorporation of biochar only or combined application with urea did not offer any short-term agronomic advantages over mineral fertilizer only at 200 or 500 kg N ha-1.

Tuesday, 13 February 2018

IBI monthly research compilation

Robert Gillett, IBI newsletter editor, is now compiling monthly summaries of biochar related research. These are being circulated to IBI members and are available from the members area of the IBI website. This is a great resource which was kicked off in November 2017... four months of the latest biochar research, compiled, summarised and searchable. Click on the link below to access the latest compilation as a sample. Do consider supporting IBI with your membership.

"Papers in the February list are from last month's new 'biochar' entries in Google Scholar. Quotes are from the papers, which are accessible through the links provided. These have been extracted by IBI Newsletter Editor Robert W. Gillett to keep the length of this addendum manageable, yet informative enough to prompt further investigation by readers. Emphasis was placed on highlighting new findings leading to practical application, but with the expectation that decisions will be informed by accessing the full publication.
Click here to access the full list."

Biochar in Vietnam - IBI report

A review of current biochar status in Vietnam

by Tran Thi Thu Hien

"Vietnam, an agricultural country, is the third largest in Southeast Asia region in terms of biochar potential. Each year, total biomass production from wood industry and crop cultivation is about 118 tons (Table 1), which is the mainly primary source of biochar feedstocks (Stefan Jirka, 2014). In recent years, the awareness about biochar benefits of Vietnamese people is increasing following to a global trend  as more large scale  field studies show the benefits of biochar use. ..."


Sunday, 21 January 2018

Biochar and maize study in Nepal

Biochar improves maize growth by alleviation of nutrient stress in a moderately acidic low-input Nepalese soil

Under a Creative Commons license
  Open Access


Soil limitations (moisture, nutrients, acidity) were manipulated one by one to find out why biochar improved crop growth.
Biochar addition increased soil pH, plant available P, K and soil moisture retention in this weathered Nepalese soil.
The biochar effect on plant growth was mainly due to alleviation of nutrient stress.


We studied the role of biochar in improving soil fertility for maize production. The effects of biochar on the alleviation of three potential physical-chemical soil limitations for maize growth were investigated, i.e. water stress, nutrient stress and acid stress. Experiments involved soils with two dosages of biochar (0.5% and 2% w:w), as well as ones without biochar, in combination with four different dosages of NPK fertilizer, water and lime. Biochar was produced from the invasive shrubby weed Eupatorium adenophorum using flame curtain kilns. This is the first study to alleviate one by one the water stress, nutrient stress and acid stress in order to investigate the mechanisms of biochar effects on soil fertility.
Biochar addition increased soil moisture, potassium (K) and plant available phosphorous (P-AL), which all showed significant positive relationship (p < 0.001) with above ground biomass of maize. However, biochar was much more effective at abundant soil watering (+ 311% biomass) than at water-starved conditions (+ 67% biomass), indicating that biochar did increase soil moisture, but that this was not the main reason for the positive biomass growth effects. Biochar addition did have a stronger effect under nutrient-stressed conditions (+ 363%) than under abundant nutrient application (+ 132%). Biochar amendment increased soil pH, but liming and pH had no effect on maize dry biomass, so acidity stress alleviation was not the mechanism of biochar effects on soil fertility.
In conclusion, the alleviation of nutrient stress was the probably the main factor contributing to the increased maize biomass production upon biochar addition to this moderately acidic Inceptisol.

Friday, 19 January 2018

More on Biochar & AD @BiomassMagazine

Biochar could benefit anaerobic digestion of animal manure @BiomassMagazine: New research by Texas A&M AgriLife Research scientists shows biochar has potential to make anaerobic digestion of animal manure a more efficient method to rid farms of waste while producing methane for energy.

see also:

Saturday, 13 January 2018

Biochar Effects on Rice Paddy: Meta-analysis

Biochar Effects on Rice Paddy: Meta-analysis


Rice is staple for nearly half of the world population. Biochar (BC) improves crop yields, reduces greenhouse gas (GHG) emissions, and immobilizes heavy metals in the soil. This study was aimed to meta-analyze the data from the published articles focused on the various BCs’ effects on rice yield, soil acidity, GHG emissions, and bioavailability of Cd and Pb. The data of pyrolysis temperature, application rate, and feedstock of BCs were categorized by using the MetaWin software for calculating the mean effect sizes (E) with 95% confidence intervals (CI). Compared to the control, the BCs increased soil pH and rice yield by 11.8% (medium E +: 0.436 to 0.439) and 16% (large E +: 0.790 to 0.883), respectively. Applying BCs derived from different feedstocks and pyrolysis temperatures reduced N2O emissions from rice paddies (large E −: − 0.692 to − 0.863). The BCs produced at 550–600°C reduced the GHG emission with medium to large negative effects (E −: − 1.571 to − 0.413). Applications of BCs at a range of 41–50 t ha− 1 were the best for rice productivity. Applications of all types and rates of BCs showed the significant decrease of available Cd by 35.4%–38.0% in a soil and led to the Cd reduction by an average of 43.6% in rice grains compared to the untreated soils. Applying BC is a promising approach to meet the challenges of sustainable global rice production, and the properties of BCs should be fully characterized and designed depending on its needs prior to its application.

Tuesday, 9 January 2018