Quantification of the Carbon Content of the Fractions of Humic Substances and Total Organic Carbon in Different Production Systems

Abstract

Soil organic matter is degraded and easily altered by the type of management. The objective of this work is to determine the total organic carbon and humic substance fractions in the organic matter of the soil with different management types and depths in the western region of Paraná, Brazil. The work was carried out in the Experimental Farm "Professor Antônio Carlos dos Santos Pessoa", belonging to the State University of the West of Paraná. Five soil management systems were evaluated: one area with corn cultivation for silage (CS); other area with succession of crops, with soybean in summer and corn in winter (SC); the next area also with succession of crops, with soy in the summer and oat in the winter (SO); the following area with permanent pasture with Tifton (PP); and the last area with crop-livestock integration (ILC). For each management system, four plots were randomly selected, in each plot three simple samples were collected in a diagonal direction to form a composite sample for the depth of 0.00-0.05 m, 0.05-0.10 m and 0.10-0.15 m. Total organic carbon, fractionation of the humic substances and the AH/AF and EA/HUM ratios were calculated. For most of the analyzed variables, it was verified that there were significant differences (P < 0.05) between the systems evaluated in the studied depths. In the evaluated areas, the PP, SO and ILC systems presented the highest carbon content for all attributes analyzed.

Carbon, Nitrogen, and Organic Matter of Soil in an Integrated Crop-Livestock System

“…This behavior can be explained by the greater deposition of crop residues on the soil surface, which was also observed by Silva et al, 2011; Batista et al, 2013; Ferreira et al, 2019. Rego et al (2017), evaluating total organic carbon contents in production systems, did not observe differences between integrated agricultural production systems versus non-integrated agricultural systems in the same layers analyzed in this study. On the other hand, when assessing grazing intensities in the ICL system, Souza et al (2009) found that the total organic carbon was reduced when grazing occurred with a stubble height of 0.10 m comparing to the ungrazed area.…”

“…The no-till system (NTS) and integrated croplivestock system (ICLS) are conservationist managements because they can maintain or increase the stock and fractions of carbon (Salton et al, 2011;Guareschi et al, 2013;Khorramdel et al, 2013;Rego et al, 2017), favoring the physical, chemical and biological properties of the soil (Chávez et al, 2011;Rosset et al, 2016). Souza et al (2009), evaluating grazing with moderate intensity in an integrated grass-soybean system conducted for ten years in NTS, found that they promoted an increase in total organic carbon (TOCS) and total nitrogen (TNS) stocks, similar what happened in notillage without grazing, however, when the grazing intensity was high, there were losses in the stocks of these elements.…”