IMPACT OF ORGANIC CARBON FRACTIONS ON SOIL STRENGTH MECHANISMS

• Grant number: 23/05538-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2023
• End date: January 31, 2024
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Renato Paiva de Lima
• Grantee: Pedro Chudzik
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Associated research grant: 21/10573-4 - Center for Carbon Research in Tropical Agriculture (CCARBON), AP.CEPID

Abstract

The continuous C input in the soil can promote significant improvements in the aggregation process and structural soil quality, regulating many soil physical processes. Studies have reported that C plays a key role in the process of soil strength gain, directly influencing cohesion, compressive properties (strength, elasticity and compressibility), soil penetration resistance and tensile strength of aggregates. However, the total organic carbon can be evaluated according to its soil stability, labile and stable fractions. The proposal of this project is to test the hypothesis that the stability and physical resistance of the soil is conferred by the greater amount of stable C in the soil. The objective of this project is to evaluate the influence of total C and its physical fractions on structure stability and physical resistance in soils with different times of agricultural land use. Therefore, soil samples will be collected in scenarios with soil C gradient and consequently different degrees of soil structure stability. The scenarios will include different phases and times of implementation of land use systems. Compressive properties will be measured in soil samples via compression test. Additionally, tensile strength tests will be performed on aggregates collected in the field. Total carbon and its respective physical fractions, as well as water-stable aggregates, will be measured and related to soil strength indicators. It is expected that the C and the conduction time of the systems induce structural stability and condition the increment in the indicators of physical and mechanical strength, in view of the greater amount of stable C in the soil. Knowledge and understanding of the role of C in soil resistance mechanisms could be a useful tool for building, via management, soils that are more resistant to deformation and rupture, and resilient in events of application of external loads. Consequently, the soil could become less susceptible to degradation, but with high physical quality for plant growth.