Interactive effects of no‐till, cereal rye, and softwood pine‐derived biochar on soil health of a no‐till northern soybean system

Climate‐smart agriculture (CSA) practices can support carbon (C) sequestration and microbial communities, yet field‐scale studies about their integrated benefits are limited. This study evaluated the integrated effects on soil health of a softwood pine‐derived biochar (10 Mg ha −1 ) and cover crop (cereal rye, Secale cereale L.) under a no‐till soybean ( Glycine max L.) system from 2022 to 2023. Treatments include no‐till only, biochar only, cover crop only, biochar + cover crop, and conventional tillage without amendment. CSA had a significant effect on soil organic C (SOC; p < 0.0001) and bacteria phospholipid fatty acid (bacteria PLFA; p < 0.0001) in 2022 and 2023, and β‐glucosidase (BG; p < 0.0001), N‐acetyl‐β‐ d ‐glucosaminidase (NAG; p = 0.0003), leucine aminopeptidase ( p < 0.0001), and phosphatase ( p = 0.0079) (pooled across years). In 2022, no‐till, biochar, and biochar + cover crop increased SOC (12%–50%) compared to conventional tillage. SOC strongly correlated with total PLFA ( R 2 = 0.81; p < 0.01), bacteria PLFA ( R 2 = 0.88; p < 0.01), and Gram‐positive bacteria PLFA ( R 2 = 0.90; p < 0.01). Cereal rye had significantly higher SOCs (+30% to +42%) than biochar, no‐till, and biochar + cover crop. Applying biochar alone or with cereal rye significantly increased activities of C‐acquisition (+108% and +131% BG, respectively) and N‐acquisition enzymes (+184% and +58.8% NAG) compared to conventional tillage. On average, SOC declined by 13% across treatments in 2023, but integrating biochar with cereal rye appeared to stabilize SOC loss, potentially mitigating positive priming effects. Overall, these results suggest that integrating biochar with cereal rye under no‐till can support soil health through synergies that promote enzyme activities, whereas integrating cereal rye with no‐till can promote SOC storage.