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

https://doi.org/10.3389/fenvs.2022.914766.

Field season 2022 started for AgriChar Estonian field experiments

Past weeks we enjoyed the warm weather in Estonian fields, this growing season 2022 we have there four field experiments! 

First of all, our new recycling fertilizer experiments focusing on granular fertilisers based on oil-shale ash and lime enriched with essential soil nutrients is past the greenhouse experiment phase and with the most promising recipe we started now field experiments in Ahja and Aovere fields in Southern Estonia. By today, both fields have also been sown to cereals (oats and barley) and let's keep fingers crossed for some decent rain now!

 

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 https://soilprotection.earth!

 We also fertilized our two field experiments in Viljandi and set them ready for new growing season. Our drainage experiment  where we added biochar as backfill filter material to see the effects on drainage water quality, has now functional, tailor-made measurement wells with V-notch that allow to record the flow rates (thanks to Pipelife Estonia). Further, with the funding from August Johannes and Aino Tiura Foundation as well as Emil Aaltonen Foundation we were able to purchase automated ultrasonic water level measurement devices produced by ELIS/sold by Konwell Estonia) that help us to record flow rates in drainage lines during the growing season. In early May 2022 we set these up while also measuring the GHG emissions from the treatments. 

 

Finally, we also started new field season for our lake sediment recycling field experiment (already sixth growing season!), collected there the leachate and sowed the plots to barley. Thanks for the great teamwork to all who participated, but especially Mina, Jure and Subin!

Our next plans are related with starting field season and measurements also here in Helsinki, with our two long-term biochar experiments. These start already 13th growing season!

Welcome to Sustainability Science Days 2022 on 18-19 May

 Warm welcome to Sustainability Science Days 2022 on 18-19 May! We especially welcome to submit abstracts to Session 13. #Carbon drawdown: Reverse-logistics for a carbon economy! Please submit your abstract by 21 Feb!

This session convenes around an urgent necessity of building up effective and acceptable ways of contributing to the removal of atmospheric CO2. The workshop draws from the ideas of sustainability science of turning towards and addressing grand systemic challenges. 

Description:

For several centuries, humans have excelled in mobilising fossil fuel reserves and converting them to atmospheric CO2. The current state of climate emergency and the need for deep-reaching societal and metabolic transformations calls for a reversal of this logic: large-scale, effective and even profitable ways of drawing carbon down from the atmosphere. This track invites papers that address all processes, mechanisms, designs and economic models in which carbon in captured through plant biomass and sequestered. 

Relevant questions and topic include but are not limited to 

• the cycles of carbon in forests, agricultural land and urban green areas 

• processes of treating streams of organic material to produce biochar and other stable carbon products and compounds 

• transformations of the forest industry to propel carbon drawdown 

• qualities and the use of biochar in different applications 

• economics, business models and regulation of carbon drawdown 

• systemic mapping of potential of and conditions for large-scale carbon drawdown in different geographical context and sectors of human activity

  
  

Conveners: Mikko Jalas (Aalto University) & Priit Tammeorg (University of Helsinki)

Submit via https://www.helsinki.fi/en/conferences/sustainability-science-days-conference-2022/call-abstracts