Effect of Biochar Application Rates on the Hydraulic Properties of an Agricultural-Use Boreal Podzol

Abstract

Boreal agriculture struggles with soils of lower agronomic value, most of which are sandy with a low water holding capacity (WHC) and prone to nutrient leaching. Biochar amendments are associated with positive effects on soil hydraulic properties and enhanced nutrient retention. However, these effects are strongly related to feedstock type and pyrolysis parameters and depend on biochar application rates and soil types. While biochar could increase the productivity of boreal agriculture by improving water and nutrient use efficiency, little is known about its effects on hydraulic processes in podzol. In this study, we investigated the effects of biochar rates (10, 20, 40, 80 Mg carbon ha−1) and maturity on soil hydrology for an agriculturally used Podzol in Labrador, Canada. The in-situ soil water content (SWC) and weather data over an entire growing season were analysed. Hydrus 1D simulations were used to estimate changes in water fluxes. SWC showed clear differentiation among storage parameters (i.e., initial, peak and final SWC) and kinetic parameters (i.e., rate of SWC change). Storage parameters and soil wetting and drying rates were significantly affected by biochar rates and its maturity. The magnitude of the changes in SWC after either wetting or drying events was statistically not affected by the biochar rate. This confirms that biochar mostly affected the WHC. Nevertheless, reductions in cumulative lower boundary fluxes were directly related to biochar incorporation rates. Overall, biochar had positive effects on hydrological properties. The biochar rate of 40 Mg C ha−1 was the most beneficial to agriculturally relevant hydraulic conditions for the tested Podzol.

Impact of biochar amendments on soil water and plant uptake dynamics under different cropping systems

“…Taken together, these findings suggest that biochar amendments in coarse-textured soils increase water retention by reducing soil evaporation loss, while allowing for more drainage for a rainfed pasture system. Similar findings have been observed in other studies (Abel et al, 2013;Altdorff et al, 2019;Arthur et al, 2015;Günal et al, 2018;Kroeger et al, 2021;Mollinedo et al, 2015;Stylianou et al, 2021), supporting the belief that even 5% biochar augmentation can increase water retention within coarse-textured soils.…”

Investigating the Influence of Biochar Amendment on the Physicochemical Properties of Podzolic Soil

“…Modern scientific literature is replete with examples of biochar's ability to improve soil physicochemical properties and agricultural conditions. However, only a small number of studies have been conducted on the biochar amendment to improve the soil performance including physicochemical properties of podzolic soil in boreal climates or ecosystems [23,[49][50][51]. This is important to note considering the boreal ecosystem is facing an increase in agricultural production and covers approximately 11% of the terrestrial land surface on Earth [48].…”

Potential of Biochar to Alternate Soil Properties and Crop Yields 3 and 4 Years after the Application

“…The experiment reported by Burrell et al [28] was run in a glasshouse for the first year and then the pots were left to fallow outside for another two years. In the study of Altdorff et al [33], the changes of soil water content were measured three years after the biochar application and two years after its reapplication.…”