Spectrophotometric method for quantification of soil microbial biomass carbon

Abstract

The search for more suitable alternatives in analytical processes is a strategy to reduce environmental damages. The present study aimed to quantify the soil microbial biomass carbon (SMB-C), establishing a comparison between the methods involving quantification of SMB-C by titration of the samples with ferrous sulfate ammonia and molecular absorption spectrophotometry methods. This comparison was performed by two soil sample tests: (i) areas of grain crops with conventional management versus notill farming; and (ii) areas with distinct phytophysiognomies in the region southern Mato Grosso do Sul state (Cerrado and Semideciduous Forest). It was found that molecular absorption spectrophotometry was an efficient tool for the determination of soil microbial biomass carbon, allowing replacement of the titrimetric method. There were significant differences in the levels of SMB-C determined spectrophotometrically in relation to those determined by titration. However, for the levels of SMB-C determined by spectrophotometry to be compared with those determined by titration, the values must be corrected by the linear regression equation Y spectrophotometry =-151.38 + 0.92532 * X titration .

Azospirillum brasilense Inoculation in a Maize–Urochloa–Rice Cropping System Promotes Soil Chemical and Biological Changes and Increases Productivity

“…The C present in the microbial biomass (MBC) was quantified using 10 g soil samples and the fumigation-extraction method [28]. The difference between the C released by the death of microorganisms via fumigation (fumigated and non-fumigated) was determined according to the methodology of [29], with reading performed using a spectrophotometer (495 nm).…”

“…To quantify the C from CO 2 (C-CO 2 ) released by the microbial activity in 100 g of soil, after incubation, the remaining sodium hydroxide was titrated with hydrochloric acid, following the method proposed by [29]. The soil incubation period was determined using the calibration curve resulting from monitoring the soil every other day using extra jars.…”

Successive processes at quarry waste dumps of various ages

“…The following parameters were determined in the soil samples: water-salt suspension pH (1:3), skeletal fraction content and soil particle size composition by pipetting with pyrophosphate peptisation of microaggregates (Beretta et al 2014), basal soil respiration, aciometric estimation of CO 2 carbonate content (Dettori and Donadio 2020) and quantification of microbial carbon biomass by spectrophotometry (da Silva et al 2016). An ecological and phytocoenotic analysis of the vegetation was performed, and the types of life forms were determined according to Coskun (2019).…”