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Easily degradable carbon – an indicator of microbial hotspots and soil degradation

Wolińska, Agnieszka, Banach, Artur, Szafranek-Nakonieczna, Anna, Stępniewska, Zofia, Błaszczyk, Mieczysław
International agrophysics 2018 v.32 no.1 pp. 123-131
arable soils, biodegradation, carbon, carbon dioxide, enzyme activity, microbial biomass, soil degradation, soil microorganisms, soil properties, soil respiration
The effect of arable soil was quantified against non-cultivated soil on easily degradable carbon and other selected microbiological factors, i.e. soil microbial biomass, respiration activity, and dehydrogenase activity. The intent was to ascertain whether easily degradable carbo can be useful as a sensitive indicator of both soil biological degradation and microbial hot-spots indication. As a result, it was found that soil respiration activity was significantly higher (p <0.0001) in all controls, ranging between 30-60 vs. 11.5-23.7 μmol CO₂ kg d.m.⁻1 h⁻¹ for the arable soils. Dehydrogenase activity was significantly lower in the arable soil (down to 35-40% of the control values, p <0.001) varying depending on the soil type. The microbial biomass was also significantly higher at the non-cultivated soil (512-2807 vs. 416-1429 µg g⁻¹ d.m., p <0.001), while easily degradable carbon ranged between 620-1209 mg kg⁻¹ non-cultivated soil and 497-877 mg kg⁻¹ arable soil (p <0.0001). It was demonstrated that agricultural practices affected soil properties by significantly reducing the levels of the studied parameters in relation to the control soils. The significant correlations of easily degradable carbon-respiration activity (ρ = 0.77*), easily degradable carbon-dehydrogenase activity (ρ = 0.42*), and easily degradable carbon-microbial biomass (ρ = 0.53*) reveal that easily degradable carbon is a novel, suitable factor indicative of soil biological degradation. It, therefore, could be used for evaluating the degree of soil degradation and for choosing a proper management procedure.