Abstract

INIESTA-MARTINEZ, Lizeth et al. Magnetism and color as indicators of changes in soil by stubble burning. Bol. Soc. Geol. Mex [online]. 2023, vol.75, n.2, A280323.  Epub June 07, 2024. ISSN 1405-3322.  https://doi.org/10.18268/bsgm2023v75n2a280323.

Agricultural burning is a common practice in sugarcane plantations in Mexico that exerts positive and negative effects on the soil. However, there is no consensus on the soil changes caused by the burning, thus highlighting the need to study this phenomenon through low-cost and quick-to-analyze indicators. Magnetic and color techniques can be indirect, fast, and cheap methods that can help to understand the chemical changes that agricultural burning causes to soils. We aim to evaluate the color and magnetic susceptibility of the soil as indicators of changes caused by agricultural burning. The study was carried out on a Vertisol grown with sugarcane in Tabasco, Mexico. Soil samples were taken at ten sites within the plot, at each site soil samples were collected every two centimeters up to 20 cm of soil depth, before and after agricultural burning. In total, 200 soil samples were analyzed. Temperatures were recorded during agricultural burning at 0, 2, and 5 cm depths. The parameters and color indices were analyzed in the CIE-L*a*b* system in the soil samples, and the high and low-frequency magnetic susceptibility were measured with Bartington MS2 equipment. After agricultural burning, the soils showed increased dark tones at four centimeters depth. Also, magnetic parameters showed changes in soil for the 4 cm in depth after the agricultural burning. The results show that color and magnetic susceptibility are efficient soil properties for identifying soil modifications caused by agricultural burning. In this case study, the effect of agricultural burning on sugarcane crops was short-term and shallow in the soil.

Keywords : Magnetic Susceptibility; CIE-L*a*b*; RGB; Redness Index,Vertisol.

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