Lime and gypsum application: implications in soil organic matter stabilization processes

• Grant number: 23/14822-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2024
• End date: March 31, 2025
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Francisco Ruiz
• Grantee: Giovanna Campanholi Delghingaro
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Soil plays a crucial role in global climate control. Since agriculture contributes to approximately 22% of anthropogenic carbon dioxide (CO2) emissions, it is essential to adopt agricultural practices that encourage carbon sequestration in the soil. Practices such as liming and gypsum application are vital for increasing agricultural production; however, little is known about their effects on (de)stabilization processes of soil organic matter (SOM). This is likely due to the trade-off between increasing SOM and its stabilization through organo-mineral interactions, as opposed to the increased microbial activity resulting from soil pH elevation and reduced aluminum toxicity, which can lead to greater SOM decomposition. In this context, this project aims to evaluate the effects of soil correction (liming and gypsum application) on SOM dynamics, taking into consideration (i) the formation of organo-mineral interactions with Ca and Mg and (ii) the increase in microbial activity after the application of different types of limestone (calcitic and dolomitic) and gypsum. An experiment will be conducted in a greenhouse, in which Brachiaria grass will be grown with different types of limestone (dolomitic and calcitic) and gypsum. Soil heterotrophic respiration, microbial biomass, and activity will be assessed and used as indicators of the biological stability of SOM. Furthermore, physical fractionation of soil organic matter combined with chemical extractions will be used as a proxy for organo-mineral interactions. The obtained variables will be included in a model to explain the (de)stabilization processes of SOM. Understanding these processes will contribute to the improvement of agricultural practices, promoting more effective SOM management, which is crucial for advancing agriculture and addressing climate change.In this context, this project aims to evaluate the effects of soil correction (liming and gypsum application) on SOM dynamics, taking into consideration (i) the formation of organo-mineral interactions with Ca and Mg and (ii) the increase in microbial activity after the application of different types of limestone (calcitic and dolomitic) and gypsum. An experiment will be conducted in a greenhouse, in which Brachiaria grass will be cultivated with different types of limestone (dolomitic and calcitic) and gypsum. Soil heterotrophic respiration, microbial biomass, and activity will be assessed and used as indicators of the biological stability of SOM. Furthermore, physical fractionation of soil organic matter combined with chemical extractions will be used as a proxy for organo-mineral interactions. The obtained variables will be included in a model to explain the (de)stabilization processes of SOM.Understanding these processes will contribute to the improvement of agricultural practices, promoting more effective SOM management, which is crucial for advancing agriculture and addressing climate change.