Ash and biochar amendment of coarse sandy soil for growing crops under drought conditions

Abstract

Appropriate soil amendments may increase plant available water and crop yields on coarse sandy soils under drought conditions. In this study, we applied straw ash or straw biochar from gasification to a Danish coarse sandy subsoil to assess the effects on soil water retention, evapotranspiration and crop yields. Spring barley (2016, 2017) and winter wheat (2018) were grown over three years in columns containing 25cm of organic matter‐rich topsoil, 80 cm of amended coarse sandy soil (1.5%, 3%, 6% wt. ash or 1% wt. biochar or control soil) and 45 cm of un‐amended subsoil. Precipitation, evaporative demands and soil moisture were recorded across the growth seasons, with 2018 having severe drought conditions. This year evapotranspiration levels increased with increasing ash and biochar content (by 54% and 33% for the 6% ash‐ and 1% biochar‐amended soils, respectively), and plant dry matter increased by 18% in both the 1% biochar‐ and 6% ash‐treated soils compared to the untreated control. A linear relationship was established between in situ field capacity and ash dosage (R2 = .96), showing an increase of 2.2% per percentage (wt.) of ash added, while the 1% biochar treatment increased the capacity by 3.5%, indicating a higher efficiency than for ash. However, we did not find significant positive effects on grain yields. The results show that ash and biochar have the potential to significantly increase soil water retention, evapotranspiration and total dry matter yield in drought conditions, but that this may not correspond to an increase in grain yield.

Valorization of sorghum ash with digestate and biopreparations in the development biomass of plants in a closed production system of energy

“…The addition of straw ash to soil significantly improved the dry weight of grains, shoots and roots of early rice 25 . Straw ash or straw biochar significantly increased also soil water retention, evapotranspiration and yield of spring barley and winter wheat in drought conditions, although it did not influence their grain yield 26 . It is also believed that ash from burned plants can be more useful as a fertilizer than sewage sludge due to its composition free of toxic compounds 27 .…”

Innovative Pathways for the Valorization of Biomass Gasification Char: A Systematic Review

“…More studies should consider this cascade approach in which the waste originating from a process becomes the feedstock for a further process. In multiple studies, the final valorization pathway was soil application for carbon sequestration purposes [101]. The continued use of the recycled chars in subsequent applications without regeneration was also driven by the high cost of regeneration [126].…”

“…This study was followed by a long-term study in which spring barley and winter wheat were grown during a three year period in GC-amended soil. An application rate of 1 wt.% increased the in situ field capacity of the subsoil by 3.5% and led to a higher total dry matter yield (18%); however, no positive impact on grain yield was observed [101].…”

Role of biochar toward carbon neutrality

“…The indirect effect of biochar on plant growth promotion should not be neglected. Improved water holding capacity (Bruun et al 2022;Razzaghi et al 2020), enhanced aggregation characteristics (Islam et al 2021), suppressed acidity (Dai et al 2017), reduced salinity (Wang et al 2022f ), suppressed activities of pathogens (de Medeiros et al 2021), as well as enhanced activities of soil fauna (Lehmann et al 2011) contribute to biochar's performance in promoting plant growth.…”