This study aimed to analyze the carbon (C) stock and stabilization of soil organic matter in particulate- and mineral-associated fractions across different land use systems after 32 years of experimentation in the Brazilian Cerrado. The experiment was established in 1991 and was performed in Planaltina-DF. The treatments evaluated included continuous pasture with monoculture grasses; integrated crop–livestock systems under no tillage; continuous cropping under no tillage; minimum tillage; and the preservation of the native Cerrado biome in its original condition. Soil sampling was performed to a depth of 30 cm. Carbon and nitrogen (N) stocks were quantified for the years 2001, 2009, 2013, and 2023, with soil organic matter fractionation performed on samples from 2023. Land use change resulted in significant losses of soil C and N in areas managed with conventional soil preparation practices. Systems that promote plant diversity, such as integrated crop–livestock systems, enhanced soil C and N stocks (72.8 and 5.5 Mg ha⁻¹, respectively) and increased both particulate organic matter and mineral-associated fractions, most of which were in more stabilized forms. Integrated crop–livestock systems are management practices that offer an effective alternative to present methods in terms of combating climate change and supporting ecosystem sustainability.

Elephant grass has high biomass production potential and can benefit from biological nitrogen fixation (BNF) as its main external nitrogen source. This study evaluated the effect of BNF on biomass productivity and total nitrogen accumulation in different elephant grass genotypes. This experiment was conducted in a 120 m² concrete tank filled with soil labeled with ¹⁵N to estimate the contribution of BNF. The experimental design was randomized blocks with four replications, and the evaluation was over three years of cultivation, with semiannual cuts. The productivity of fresh and dry mass of the shoot, Nitrogen (N) accumulation, and the contribution of BNF by the ¹⁵N natural abundance technique were evaluated. The annual average of BNF was 38%. There was a statistical difference between the treatments, with the genotype P13G13 presenting fresh and dry mass productivity 50% higher than P6G4. The annual average of fresh mass, dry matter, total N, and N derived from BNF in the genotypes was approximately 70, 30, 100 Mg ha⁻¹, and 35 kg ha⁻¹, respectively. The results obtained by the P13G13 genotype allow us to recommend its use for biomass production aimed at bioenergy, favoring sustainability, reducing greenhouse gas emissions, and dependence on synthetic nitrogen fertilizers.

Objetivo: O presente estudo objetivou avaliar a influência de alguns diferentes sistemas de manejo utilizados nessa região na biomassa e atividade microbiana de em área Cerrado. Método: Em área localizada no bioma Cerrado integrante do MATOPIBA foram avaliados diferentes sistemas de manejo do solo, sendo eles área com Vegetação Nativa de Cerrado típico (VNC); Sistema de Plantio Convencional (SPC); Integração Pecuária floresta (IPF); Sistema de Plantio Direto com 6 anos de adoção (SPD6); Sistema de Plantio Direto com 8 anos de adoção (SPD8) e Sistema de Plantio Direto com 17 anos de adoção com ILP nos últimos 3 anos (SPD17+ILP3). Foram realizadas coletas de solo nas profundidades de 0-5, 5-10 e 10-20 cm, para análise de Carbono da biomassa microbiana (Cmic), taxa de respiração basal (RBS) e com esses resultados foi realizado cálculo para obtenção do valor de quociente metabólico (qCO2). Resultados e conclusões: A substituição da vegetação nativa de Cerrado por sistemas de manejo do solo, com a produção de culturas anuais sob o sistema de plantio direto e sistema de plantio convencional, causou alterações significativas nos atributos microbiológicos do solo promovendo redução nos teores de carbono da biomassa microbiana, enquanto o sistema integração pecuária floresta manteve teores próximos ao da vegetação nativa. Implicação da pesquisa: O estudo evidência um sistema de manejo do solo entre alguns dos utilizados na área de cerrado do MATOPIBA que mais favorece a atividade microbiana e consequentemente a melhoria da qualidade do solo. Originalidade/valor: É uma pesquisa nova na região, sendo importante a geração de dados sobre os atributos microbiológicos e consequente qualidade do solo para a produção de grãos.