Monday, 5 September 2022

Doctoral thesis defence of Subin Kalu successful!

 We're really proud for the success of our group member, Subin, who has completed doctoral studies and defended his doctoral thesis on 2 September 2022. The discussions with the opponent Professor Claudia Kammann were excellent (as was inspiring her talk on 1 September)! 

Subin has been working with us since 2017, and has been extremely hardworking and smart on finding the mechanisms behind biochar-soil nutrients interactions. His first paper investigated plant growth response to biochar addition. Over the 8 years in two soils, biochars increased plant growth in only 2 cases when the previous growing seasons were planted with legumes. For more details, please see:
 Kalu, S., Simojoki, A., Karhu, K.,  & Tammeorg, P. (2021). Long-term effects of softwood biochar on soil physicalproperties, greenhouse gas emissions and crop nutrient uptake in twocontrasting boreal soils. Agriculture, Ecosystems & Environment. 316: 107454.
Second paper showed that biochars increased the loss of ammonium ions and increased the retention of nitrate ions in the soil whereas increased the plant availability of N derived through mineralization of soil organic nitrogen. See:
Kalu, S., Oyekoya, G. N., Ambus, P., Tammeorg, P., Simojoki, A., Pihlatie, M., & Karhu, K. (2021). Effects of two wood-based biochars on the fate of added fertilizer nitrogen—a 15 N tracing study. Biology and Fertility of Soils, 57, 457-470.
His third paper, biochars' abilities to reduce nitrogen leaching were tested in clayey soil. Out of two biochars, the one with the large surface area reduced the leaching of nitrate. See more:
Karhu, K., Kalu, S., Seppänen, A., Kitzler, B., & Virtanen, E. (2021). Potential of biochar soil amendments to reduce N leaching in boreal field conditions estimated using the resin bag method. Agriculture, Ecosystems & Environment, 316, 107452. 
And in his fourth paper (actually just three are required for doctoral degree, so exceptional achievement) found that biochars increased crop yield even after seven years of application in sandy soil. Biochars can decrease N2O emissions mostly during the peak emission period. 
See: Kalu, S., Kulmala, L., Zrim, J., Peltokangas, K., Tammeorg, P., Rasa, K., ... & Karhu, K. (2022). Potential of biochar to reduce greenhouse gas emissions and increase nitrogen use efficiency in boreal arable soils in the long-term. Frontiers in Environmental Science.

 And of course,  the latest biochar doctoral thesis can be found here

 Well done, Subin, the doctoral sword is well deserved!


Tuesday, 30 August 2022

Subin Kalu will defend the doctoral dissertation on 2 Sep 2022

 On Friday, 2 September, our group member Subin Kalu will publicly defend his a dissertation that shows biochar can be a promising tool in mitigating the environmental impacts of agriculture also in Finland. He found that biochar addition to soil can reduce nitrogen leaching from agricultural soils to waterways, and reduce the emissions of N2O, a potent greenhouse gas.   The public examination will take place at the following address: EE-Building, Walter Hall, Agnes Sjöberginkatu 2 at 12 o'clock. 

Subin Kalu preparing for thesis defense

Professor Claudia Kammann, Hochschule Geisenheim University, will serve as the opponent, and those interested are welcome also to listen to her talk on 1 September  on the topic “Biochar use in agriculture, urban landscapes and building materials: An underestimated NET with benefits and economic prospects”. The talk will start at 14:30, at Latokartanonkaari 7, B-building/Forest Sciences building, Seminar room 332, 3rd floor.

 Subin did his PhD at the Faculty of Agricultural and Forest Sciences, in a joint collaboration between researchers from the Department of Forest Sciences and Agricultural Sciences as well as with researchers from Natural Resources Institute Finland (LUKE) and the Finnish Meteorological Institute.

In his dissertation, Subin  studied the long-term effects of biochars in four different agricultural field experiments in southern Finland where biochars were applied two to eight years before. Subin says, “Although the effects of biochars were not consistent throughout these years, some improvements in plant growth were observed when the previous growing seasons were planted with legumes. This special biochar and pre-crop effect warrants further study”. He added, “in some cases, biochars showed tendencies to improve agricultural benefits such as increases in crop yield, soil nitrate retention and plant nitrogen uptake while reducing the negative environmental effects such as decreases in soil N2O emissions and nitrate leaching”.


Even if the observed positive agricultural and environmental effects were not consistent in all fields in the long-term, no negative effects of biochar were observed over these study periods. This indicates that the application of biochar in agricultural soils is a safe way of enhancing soil carbon storage.

Warm welcome!

Dissertation in electronic form:

Tuesday, 23 August 2022

Our field experiments in Estonia harvested for 2022!

 Great success! Just before the rains we managed to sample and harvest our recycling fertilizer experiments focusing on granular fertilisers based on oil-shale ash and lime enriched with essential soil nutrients in Ahja and Aovere fields in Southern Estonia. The growing season was rather dry also in Estonia, but preliminary results are promising, both 2,5 t/ha and 5 t/ha application rates of fertilizer seemed to increase the yields. Next we will analyze the samples and finalize project reporting.

Dream Team of AgriChar group together with Estonian University of Life Sciences people managed well to sample and harvest the plots!

In this project we work in synergy with Estonian NGO Soil Innovation Cluster and Estonian University of Life Sciences, University of Tartu  and Ekosovellus and the aim of our work package is to test most suitable fertilizer recipes. Stay tuned for the results and check also other interesting results from the Cluster website!

Further, also our sediment recycling long-term field experiment and biochar drainage experiment were also sampled for plant and soil samples, as well as for leachate samples. And, of course, also the GHG emissions from the biochar and control treatments. This project is funded by Tiina and Antti Herlin Foundation, August Johannes and Aino Tiura Foundation as well as Emil Aaltonen Foundation. Thanks Mina, Subin and Jure for the excellent job!

Wednesday, 8 June 2022

Research seminars and collaboration with Dr. Dilfuza Egamberdieva

We have been happy to host Dr. Dilfuza Egamberdieva, research associate at the Leibniz Centre for Agricultural Landscape Research (ZALF), Germany, and Head of the Research Lab at the National University of Uzbekistan here in Helsinki. Dilfuza is a renowned environmental microbiologist and soil scientist. The main focus of her research is directed toward an understanding of the structural and functional organization of plant and soil microbial communities under various environmental ecosystems and their role in soil fertility and crop productivity. Since 2015 she is involved in biochar research, particularly as a beneficial soil amendment, and its impact on crop productivity.  She has joined our lab activities and supports research, particularly she contributes to our oil shale ash recycling work.

Dr. Dilfuza Egamberdieva has studied plant and soil microbial communities under various environmental ecosystems, including Aral sea watershed.

 In early June 2022 we had several seminars where Dr. Egamberdieva shared both her latest research and also advice for early career researchers on how to establish and keep alive successful research networks across the globe. As she has co-authored over 200 publications and belongs among the top 1 % of active reviewers according to Publons, her insights were really inspiring for us!  In the research seminar,  she shared her latest research on how biochars have been found to enhance legume-rhizobium symbiosis in challenging environments. Different biochars have different effects, and according to her experience, HTC hydrochar made of maize silage can be rather promising solution under many conditions. Hope to share soon our joint publications!


Thursday, 19 May 2022

Can the agricultural and environmental benefits of biochars be expected after several years of field application?


Application of biochars to soils is gaining popularity because of their ability for sequestering atmospheric carbon as well as bringing beneficial agricultural and environmental effects. Biochars have potential to improve soil fertility and enhance crop productivity as well as reduce greenhouse gas (GHG) emissions and nutrient leaching. However, one of the important knowledge gaps in biochar research is whether these beneficial effects exist after several years of field application. 

To know this, we measured properties of plant and soil, fluxes of greenhouse gases, and leaching of nitrogen from four already established field experiments on various types of Finnish soils where biochars were applied 2-8 years prior to this study. This includes two of AgriChar long-term biochar experiments from Viikki, sampling was done in 2018.

The major effects observed were:

1)      No effects of biochar on crop yield were observed on two field experiments but the spruce biochar increased barley grain yield by 65% after 7 years of field application in a coarse-textured Umbrisol in Viikki. As a result, CH4 + N2O emitted per ton of grain yield is reduced by 43%. Similarly, in a clayey Cambisol, where spruce and willow biochars were applied 2 years ago, only the spruce biochar significantly increased oat grain yield by 75%.

2)      In the clayey Cambisol, the increased crop yield by the spruce biochar was related to its ability to hold nitrate ions, which was available for plant uptake. However, such effect was not observed for the willow biochar. We hypothesize that the ability of retaining soil nitrate is related to the surface area of biochar since the surface area of the spruce biochar (328 m2 g-1) was much higher than the willow biochar (1.3 m2 g-1).

3)      In the same clayey Cambisol field, where mineral nitrogen leaching test was also measured, we found that biochar has potential to reduce N2O flux and nitrate leaching especially during the peak emission or leaching period. However, no clear effects on fluxes of N2O or CH4 were observed on other field experiments.

Based on this, it can be concluded that the positive effects of biochars such as increase in crop yield and plant N availability, decrease N2O emissions and N leaching could be observed even after several years of biochar application, however, it depends on soil and biochar types as well as the environmental conditions.

Please read the full study here: Subin Kalu et al. 2022. Potential of Biochar to Reduce Greenhouse Gas Emissions and Increase Nitrogen Use Efficiency in Boreal Arable Soils in the Long-Term