Aggregates and organic matter stability in soils submitted to different temperatures in West Bahia, Brazil

Abstract

Estimates indicate that about 30% of the planet's surface suffers from seasonal fires. In Brazil, in the first half of 2020 these numbers already reached 62.402 km2equivalent to 0.7% of the national territory. Due to the high temperatures that fire can reach on agricultural land, this practice can have negative consequences for the physical, chemical and biological properties of the soil. In this study four soil classes were obtained (Red Yellow Argisol, Haplic Vertisol, Red Yellow Latosol and Haplic Cambissol) predominant in the Western region of Bahia.Four samples were removed by point and then were taken to carry out analyzes at the Soil Physics Laboratory of the University of the State of Bahia. After preparing the sample, the aggregates were placed in a petri dish and then were subjected to firing in a muffle oven at temperatures of100, 200, 300, 400, and 500ºC, After cooling for 24 hours inside the muffle, they were placed in the appliance Yoder to carry out analyzes related to soil aggregation. The results showed that soils with a higher percentage of organic matter obtained the best aggregation results, as already presented by several authors. Regarding the temperature variation, when subjected to combustion at 200ºC, the soil presented a decrease in aggregation compared to the ambient temperature. However, lower averages were observed in those submitted to 300ºC with the exception of the MiAg variable. The increase in soil temperature changed the distribution of aggregates mainly in classes with a diameter smaller than the class of 1