Influence of biochar feedstock blends on soil enzyme activity, nutrient cycling, lettuce biomass accumulation and photosynthesis

• DOI: 10.1186/s12870-025-06352-w
• Publication Date: 2025-03-13T03:03:39Z
• Authors: Jiri Holatko; Jiri Kucerik; Adnan Mustafa; Kamila Lonova; Manzer H. Siddiqui; Muhammad Naveed; Tereza Hammerschm...; Antonin Kintl; Ondrej Malicek; Tomas Chorazy; Tivadar Baltazar; Martin Brtnicky
• Keywords: Nutrient cycle; Cycling; Slash-and-char

The thermal conversion of municipal sewage sludge (MSS) offers significant potential for sustainable waste management, particularly through the production biochar. This study investigates properties and soil application effects three biochar types produced via pyrolysis: (i) pure (100%), (ii) blended with sawdust (50%+50%), (iii) combined zeolite (50%+45%+5%). These biochars were applied at rates 2.5% 7.5% (w/w) to arable assessed in an 8-week greenhouse experiment using lettuce (Lactuca sativa L. var. Brilant) as a model crop. was characterized by high nitrogen, phosphorus, water-extractable calcium but exhibited low organic matter carbon content. It enhanced enzyme activities related nitrogen mineralization without affecting microbial respiration. However, rate, this caused highest chlorophyll b content lettuce, despite acidifying soil. Adding pyrolysis feedstock significantly increased matter, (with reduced recalcitrance), C: N ratio formulation promoted activity (as indicated changes respiration) nutrient cycling, glucosidase activity. Conversely, addition while increasing recalcitrance immobilization, sulfur, ammonium, calcium. At dose, + zeolite-enriched improved pH potentially retention. it did not stimulate or respiration, leading lower photosynthetic pigment levels biomassin especially higher rate. For short-term applications under conditions pot trial, sludge-sawdust demonstrated most beneficial effects, rapidly stimulating transformation. In contrast, sludge-sawdust-zeolite limited availability plant growth, suggesting may be less suitable immediate nutrition. Long-term studies are needed fully assess implications these agriculture. highlights importance composition selection tailoring meet specific crop requirements.