The effect of different rates of biochar on selected soil properties and enzymatic activity 48, 60, and 72 months after biochar application to soil was investigated. Soil enzymatic activity (dehydrogenase—ADh; phosphatase—Aph; urease—AU), the organic carbon content (TOC), the total nitrogen content (N_t), the mineral nitrogen content (NH₄⁺, NO₃⁻), and soil pH were determined. The study was conducted on Haplic Podzol originating from glaciofluvial fine-grained loamy sand. Biochar was applied to soil under winter rye (Secale cereale L.) at rates of 10 (BC₁₀), 20 (BC₂₀), and 30 t ha⁻¹ (BC₃₀). Plots with biochar-unamended soil were the control treatment (BC₀). The pH, TOC, and N_t content in the biochar-amended soil were higher compared to the control soil. A broader C:N ratio was found in the BC₀ soil compared to BC₁₀, BC₂₀, and BC₃₀. With increasing biochar rate, the content of the ammonium nitrogen form (NH₄⁺) decreased and was statistically lower than in the control soil (BC₀). The soil in the BC₂₀ and BC₃₀ treatments was characterized by the highest content of NO₃^-, whereas the lowest nitrate nitrogen content was found in the control soil (BC₀). Biochar application increased soil enzymatic activity. Dehydrogenase activity increased with increasing biochar rate. As far as phosphatase and urease activity is concerned, a similar relationship was not observed. In this case, the soil amended with biochar at a rate of 20 t ha⁻¹ (BC₂₀) was characterized by the highest phosphatase and urease activity.

Open Access Agricultural Journals published by Institute of Agricultural Economics and Information

This paper presents an ecotoxicological evaluation of soil fertilized with biogas digestate (BD) or mining waste (MS). The study was performed under pot experiment conditions. BD was added at a dose of 1.5 and 3 % to the soil. MS was applied at a dose of 10 and 20 %. Samples were collected at the beginning of the experiment and after 180 and 360 days from the start of the study. In addition, a parallel experiment with the addition of CaO was done. This was designed to eliminate the adverse effect of low soil pH on the test organisms. A battery of ecotoxicological tests was used based on tests with plants (Phytotoxkit F), microorganisms (Microtox®), and crustaceans (Daphtoxkit F). In most cases, the obtained results showed that the investigated wastes had a stimulating effect on the growth of Lepidium sativum roots. The highest content of BD was an exception since it inhibited the growth of L. sativum roots. After adding BD and MS, both the luminescence of Vibrio fischeri and the mortality of Daphnia magna was at a similar level to that in the control soil. An exception was the significant increase in the mortality of D. magna after 48 h for soil with 3 % BD. The tests performed after 6 and 12 months showed that, with time, the toxicity of the waste-amended soil fluctuated, but ultimately decreased in most cases compared to the control. The effect of the addition of CaO on the examined toxicity parameters was different and depended on the experimental variant.

Open Access Agricultural Journals published by Institute of Agricultural Economics and Information