Effects of biochar on carbon and nitrogen fluxes in boreal forest soil

Abstract

Background and aims The addition of biochar to soil may offer a chance to mitigate climate change by increasing soil carbon stocks, improving soil fertility and enhancing plant growth. The impacts of biochar in cold environments with limited microbial activity are still poorly known. Methods In order to understand to what extent different types and application rates of biochar affect carbon (C) and nitrogen (N) fluxes in boreal forests, we conducted a field experiment where two different spruce biochars (pyrolysis temperatures 500°C and 650°C) were applied at the rate of 0, 5 and 10 t ha-1 to Pinus sylvestris forests in Finland. Results During the second summer after treatment, soil CO2 effluxes showed no clear response to biochar addition. Only in June, the 10 t ha-1 biochar (650°C) plots had significantly higher CO2 effluxes compared to the control plots. The pyrolysis temperature of biochar did not affect soil CO2 effluxes. Soil pH increased in the plots receiving 10 t ha-1 biochar additions. Biochar treatments had no significant effect on soil microbial biomass and biological N fixation. Nitrogen mineralization rates in the organic layer tended to increase with the amount of biochar, but no statistically significant effect was detected. Conclusions The results suggest that wood biochar amendment rates of 5-10 t ha-1 to boreal forest soil do not cause large or long-term changes in soil CO2 effluxes or reduction in native soil C stocks. Furthermore, the results imply that biochar does not adversely affect soil microbial biomass or key N cycling processes in boreal xeric forests, at least within this time frame. Thus, it seems that biochar is a promising tool to mitigate climate change and sequester additional C in boreal forest soils.

Biochar influences nitrogen availability in Andisols of north Idaho forests

“…During the initial stage of biochar incubation, microbial assimilation of the labile C associated with biochar could have led to an increased immobilization of N into microbial biomass. Past studies have shown higher microbial biomass growth with biochar addition [74][75][76]. Nevertheless, the recycling speed of organic matter seems to be similar among soils with and without biochar after 3 months of incubation, with the turnover of small organic N not affect by biochar.…”

Biochar as adsorbent in purification of clear-cut forest runoff water: adsorption rate and adsorption capacity

“…As a regenerable adsorbent, biochar could be used as a soil amendment following the adsorption-based water purification. Biochar addition has been found to improve soil properties and the growth of crops and trees (Biederman and Harpole 2013;Lehmann and Joseph 2015;Palviainen et al 2018), and nutrients adsorbed onto biochar are easily available for plants when placed in the soil (Taghizadeh-Toosi et al 2012). Therefore, the utilization of biochar as an adsorbent can further improve its potential as a soil amendment.…”

“…Previous laboratory experiments indicate that biochar can adsorb compounds from water; however, these experiments have typically been done for single compounds, whereas simultaneous adsorption of several compounds from natural waters has not been studied before. As multiple compounds compete simultaneously for the adsorption places in the adsorption process (Palviainen et al 2018), all dissolved compounds in the water can affect the performance of biochar in nutrient reclamation. The chemical composition and nutrient concentrations of peatland forest runoff water differ significantly from agricultural or urban runoff waters (Oliveira et al 2018).…”

Purification of Forest Clear-Cut Runoff Water Using Biochar: A Meso-Scale Laboratory Column Experiment

“…After biochar is saturated with nutrients, it can be used for soil amendment. Biochar addition improves soil properties, increases carbon sequestration, reduces the need for fertilizers and improves the growth of trees [45,[86][87][88]. Thus, biochar could offer an innovative, inexpensive, renewable and 100% recyclable material for water purification and nutrient recycling, thereby allowing the responsible utilization of natural resources.…”

“…Consequently, biochar can provide a lower cost alternative to activated carbon [41,42]. Biochar has many applications in environmental management and has been used in soil conditioning, soil remediation and carbon sequestration [43][44][45]. In recent years, there has been increasing interest in using biochar in contaminant removal from agriculture and urban runoff water [46].…”