EMISSÕES DE N2O E CO2 INFLUENCIADAS POR SISTEMAS DE MANEJO DO SOLO E PLANTAS DE COBERTURA NO CERRADO BRASILEIRO

Abstract

Since the industrial revolution (1750-1850), the intensification of anthropogenic activities has led to an increase in greenhouse gas (GHG) emissions, promoting an increase in the global average temperature (~1.5°C) and intensifying the problem of climate change. Countries are committing to adopt practices that will reduce their emissions. In this sense, initiatives have emerged with the aim of developing technological strategies to reduce GHG emissions. Thus, through this research, we aim to study what would be the best management of soil preparation associated with different cover crops and main crops on carbon dioxide (CO2) and nitrous oxide (N2O) emissions. A long-term experiment located in the city of Costa Rica – MS, implemented in 2005, was selected. A strip design was used with five treatments and four replications: SA-PC: soil managed in a conventional system, with soybean and cotton cultivation in the main crops and fallow in the off-season; SA+M: soil managed in a direct planting system, with soybean and cotton cultivation, according to the corn harvest in the off-season; SA+C: soil managed in a direct planting system, with cultivation of soybeans and cotton, crotalaria sp. In the winter; SA+B: soil managed in a direct planting system, with the cultivation of soybeans and cotton as the main crops, Brachiaria sp. in the off-season; SA-PD: soil managed in such a way that the soil preparation system used was direct planting, with soybean and cotton cultivation in the main crops, and fallow in the off-season. The evaluation period was from February 2022 to August 2023, using manual static gas collection chambers. The objective was to evaluate the impact of adopting different management practices such as direct planting system and the inclusion of cover crops on CH4 and CO2 emissions. The data obtained were submitted to ANOVA (5%), and the means were compared using of the Tukey test. CO2 and N2O emissions were significantly affected by the evaluated treatments, both in the cover crop period and in the cotton cultivation period. Fluxes vary between 10 and 270 µg m-2 h-1 for N2O; and 40 and 115 mg m-2 h-1 for CO2, with the highest peaks being recorded during the period of some present event, such as sowing, fertilizing and harvesting. Variations in observed flows significantly impacted accumulated N2O and CO2 emissions. The results generated indicate that adequate soil preparation management and appropriate nitrogen fertilization have significant impacts related to gas emissions, both carbon dioxide and nitrous oxide.