Calcium speciation in the solution and its role in the organic carbon stabilization, in the microbial community, and in the production of corn in soils treated with limestone and phosphogypsum

• Grant number: 21/05497-7
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: April 01, 2022
• End date: February 29, 2024
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Luís Reynaldo Ferracciú Alleoni
• Grantee: Christian Lopes
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Calcium (Ca) is a primary nutrient for plants, and its role is related to stocks aimed at plant nutrition, effects on chemical stabilization and physical protection of organic matter and on the soil aggregation. Its presence in agriculture is closely linked to the use of soil amendments, such as limestone and phosphogypsum, notably in no-till. As there is no soil disturbance, the effect of limestone tends to be restricted to the superficial layers, while phosphogypsum is able to improve the subsurface environment for root development of crops, particularly due to the increase in the Ca content. The texture of the soils can interfere with the accumulation of Ca and its relationships with other cation or organic or ions, depending on the pH and CEC. The detailed understanding of Ca dynamics in agricultural systems is little known, mainly in relation to its effect on the stabilization of organic carbon and microorganisms, directly, due to the balance between cations, or due to the effect on pH and changes in the microbial community from this practice. This project intends to study the dynamics of Ca in soils with contrasting textures that received limestone and phosphogypsum, with emphasis on the evaluation (i) of Ca species in solution, (ii) the influence of exogenous calcium on the accumulation and stabilization of organic carbon; (iii) the binding energy between Ca and organic anions and the affinity of Ca to interact with specific groups of organic matter and root exudates; (iv) the influence of the balance between calcium and other cationic macronutrients in the soil; (v) the quantity and quality of the community of decomposing microorganisms; and (vi) production, root length, root surface, root CEC and constituents of the cell wall of corn.