Exploring the effects of one-time biochar application with low dosage on soil health in temperate climates

The application of biochar to increase agricultural productivity has sparked considerable attention, yet our understanding of the impact of a low biochar dosage on soil health remains limited. It was hypothesized that a one-time application of biochar, combined with manure and/or fertilizer, at a low dosage would lead to improvements in both soil health and crop productivity compared to soil without biochar. It was established that soil with biochar exhibited significantly higher (P < 0.05) levels of available nitrogen, while orthophosphate levels were comparatively lower (P < 0.05). Soil water infiltration experienced a substantial increase of over 85% (P < 0.05) when biochar was incorporated with manure. Additionally, the blending of biochar with manure and fertilizer led to an increase in soil microbial biomass (P < 0.05). Principal components analysis determined that 45% of the variance in the data, based on the differentiation in microbial carbon source metabolism, was due to cropping season. There was no significant effect of biochar on crop nutrient acquisition, but a 27% increase in crop yield occurred in soils amended with biochar (481 g m⁻²) compared to those without biochar (379 g m⁻²). Additionally, a latent effect of biochar on crop yield, with the highest yield (P < 0.05) observed in the final year of this study in the soil amended with biochar was noted. While results from this study only partially confirmed this hypothesis due to the limited influence of biochar on all evaluated soil properties and crop parameters, it is crucial to underscore the substantial role it plays in enhancing agroecosystem productivity and upholding environmental integrity.