Greenhouse gas mitigating potential using lime and calcium and magnesium silicate in a long-term no-tillage system

• Grant number: 23/18096-6
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: August 01, 2024
• End date: February 29, 2028
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Carlos Alexandre Costa Crusciol
• Grantee: João Henrique dos Santos Ferreira
• Host Institution: Faculdade de Ciências Agronômicas (FCA). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Associated research grant: 21/10573-4 - Center for Carbon Research in Tropical Agriculture (CCARBON), AP.CEPID

Abstract

The agricultural activity holds fundamental importance from both social and economic perspectives; however, it accounts for approximately 20% of global anthropogenic greenhouse gas (GHG) emissions, such as methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2). Adjustments in production systems and soil management can mitigate these emissions, enhance carbon (C) sequestration in soil, and elevate the environmental significance of agricultural activity. Although liming is a common practice in Brazilian agriculture to improve the fertility of acidic soils, enabling higher production of aboveground and belowground biomass and soil aggregation, limestone dissolution generates CO2 from calcium and magnesium carbonate. The use of alternative amendments, such as calcium and magnesium silicate, proven effective in acidity correction, represents a more sustainable option, as the soil reaction product does not generate CO2, despite not preventing emissions from increased soil respiration. Mitigation of GHG emissions in intensified agricultural areas will occur when emissions decrease and C input via plant biomass increases. Soil acidity correction, particularly with silicate sources, combined with the cultivation of high biomass plants, such as forage crops in intercropping systems, may contribute to a positive balance and increased C stocks in soil. The study aims to evaluate GHG emissions throughout the soybean and maize production cycle intercropped with Urochloa ruziziensis along with different soil amendments, and to investigate soil organic matter dynamics. The experiment, initiated in 2006, is part of the Global Long-Term Agricultural Experiments Network (GLTEN - Rothamsted Research, UK). The experiment tests the interaction of two factors: i) soil correction (no correction, limestone, and silicate correction); ii) intercropped maize cultivation (with and without U. ruziziensis). GHG emissions, biochemical nature of crop residues, soil C stock, quantity and quality analysis of organic matter, and C balance in systems will be assessed in the agricultural years 2023/2024, 2024/2025, and 2025/2026.