Soil Microbial and Physicochemical Changes After the Addition of Biochar, Bacterial Inoculums and Nitrogen Fertilizer

Addition of biochar is often proposed as an improving agent of soil properties. The combination of biochar (BCH) with mineral or biological amendments in order to improve its influence on soil-plant properties compared to the unamended BCH was vastly studied. Bacterial inoculums as a promising additive to BCH amendment are highly dependent on BCH quantity, its feedstock and soil state. Luvisol from a protection zone of water sources was used in pot experiment set-up. The changes in physicochemical properties (pH, cation-exchange capacity - CEC) and biological soil activities (soil enzymes: urease, phosphatase and laccase activity and total bacteria content) after the addition of beech wood biochar combined with the addition of bacterial inoculums (Bacofil and Novarefm) and nitrogen fertilizer after two growing cycles of Lactuca sativa var. capitata were studied using spectrophotometry methods. Increased pH and CEC values were detected in biochar amended treatments. The increase of laccase activity claimed on BCH additives promoting effect, especially in a case of Bactofil inoculum amendment. Nevertheless, BCH suppressed acid phosphatase activity in all the BCH additives equally. Whereas urease activity and total soil bacteria extraction remained unchanged in BCH amended treatments compared to control.