Assessment of soil quality after biochar application based on enzymatic activity and microbial composition

Abstract

Soil microorganisms play a key role in many biochemical processes essential for the environment and for the ecological and production functions of soils, hence they are very important quality indicators. The study aimed at evaluating the effect of 1 and 2% additions of wheat and miscanthus straw biochars on soil enzymatic activity (dehydrogenases, urease, phosphatases) and the number of microorganisms (bacteria, fungi, actinobacteria). Pot experiments were carried out on soil with a loamy sand texture. The geometric mean of enzyme activities, biological index of fertility, and the integrated total enzyme activity index were used to explore the relationships between soil enzyme activities and the microbiological and chemical properties of soil. The addition of 1% miscanthus straw biochar had the most beneficial effect on the number of bacteria and fungi (increase by 380 and 26%, respectively), and 1% wheat straw biochar on the number of actinomycetes (increase by 273%). The correlation analysis between the number of actinomycetes and the chemical parameters of the soil showed the significant effect of the content of N total (r = 0.76) and C total (r = 0.85). The values of biological index of fertility, total enzyme activity index and geometric mean of enzyme activities indexes showed that the best quality of soil was produced by a 2% addition of wheat straw biochar.

Cavitated charcoal -- an innovative method for improving the biochemical properties of soil

“…The sorption capacity of charcoal and biochar is determined, among others, by the concentration of heavy metals in the soil solution. In unpolluted soils, the natural consequence of using these materials is the reduction in the content of the most available element forms (Miura and Shiratani, 2018;Mierzwa-Hersztek et al, 2019). In our study, the increase in soil pH after the use of CHAR-C was one of the important factors reducing the content of the most available heavy metals (Gondek and Mierzwa-Hersztek, 2016).…”

“…Recent studies indicate that thermally transformed organic materials, including charcoal and biochar, exhibit sorption capacity for heavy metal ions (Miura and Shiratani, 2018;Mierzwa-Hersztek et al, 2019). These materials have a large specific surface area, i.e., a surface on which there are functional groups that are active in the sorbing of heavy metal ions.…”

“…The cause could have been, inter alia, increased EC values and limited availability of other nutrients. The study results published by Mierzwa-Hersztek et al (2019) indicated that the interaction of many factors significantly affects the enzymatic activity and microbiocenotic composition of soil.…”

“…Some studies also indicate the sorption capacity of these materials in relation to nutrients. According to Yao et al 2012, thermally converted organic materials can effectively sorb nitrate nitrogen, ammonium nitrogen or phosphates; however, the properties of such materials, including pH, surface acid groups, and ion exchange capacity, can have a great impact on the ability to adsorb nutrients (Yao et al 2012, Morales et al 2013, Mierzwa-Hersztek et al 2019. Our results indicate that in addition to improving soil properties, there is also a risk of limiting the availability of nutrients after applying charcoal or biochar to the soil.…”

Trace Elements Composition and Enzymes Activity of Soil Amended with Municipal Sewage Sludge at Three Locations in Kentucky

“…Investigators reported that SS added to agricultural soil increased the organic matter content from 1.4 to 4.8% when applied at 20 g kg−1 while, the estimated trace metals in soils were either below Cu, Fe, Mn, Mo, Zn, and Pb or within Co, Ni, Cd, and Cr maximum permissible levels [44]. In addition, Mierzwa-Hersztek et al [45] reported a positive correlation between microbial population and soil pH. Mixing SS amended soil with lime (calcium carbonate) or biochar (a carbon-rich product obtained when biomass, such as wood, manure, or leaves, is heated in a closed container) has been proposed to reduce soil contamination by trace metals due to their impact soil pH [46,47].…”