Organic matter quality and carbon in the soil in a maize-forage intercropping system under nitrogen fertilization

• Grant number: 21/05167-7
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: October 01, 2021
• End date: September 30, 2024
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Ciro Antonio Rosolem
• Grantee: Laudelino Vieira da Mota Neto
• Host Institution: Faculdade de Ciências Agronômicas (FCA). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Company: Universidade de São Paulo (USP). Escola Politécnica (EP)
• Associated research grant: 20/15230-5 - Research Centre for Greenhouse Gas Innovation - RCG2I, AP.PCPE
• Associated scholarship(s): 22/01234-4 - Mid-infrared spectroscopy coupled with process-based modelling to assess soil organic matter dynamics in a tropical maize-forage intercropping system, BE.EP.DD

Abstract

Understanding the carbon flow (C) is essential for soil conservation and agriculture management in the context of climate change. The dynamics of C and nitrogen (N) in intercropped systems is complex and little is known about their implications for stabilization, persistence and C flow in fractions of Soil Organic Matter (SOM). The objective is to evaluate the effect of N supply in consortium maize forage on the quantity, quality, and isotopic ratio of C stored in the soil profile over time. The experimental area has been conducted since 2014, the treatments being: forages (U. ruziziensis, U. brizantha and M. maximum) and doses of N (0, 90, 180, and 270 kg ha-1), with maize and forage cultivated consortium in the summer. The research will be carried out with soil samples collected in 2014, 2017, 2019, 2020, 2021, and 2022, at doses 0 and 270 kg ha-1. The isotopic ratio and C and N levels will be determined in the 0.0-0.1, 0.1-0.2 and 0.2-0.4, 0.4-0.6, 0.6- 0.8 m. The quality of SO (physical and chemical fractions), degree of humification, and C (CE) stock will be investigated from 0.0 to 0.4m. Structural carbohydrates (cellulose, hemicellulose, and lignin) in corn and forage samples will be determined. The accrue of C by the organic residues of forage and maize since 2014 will be applied in a mathematical model, parameterizing the conversion of the C from the residues to the C of the soil. Maize productivity for 2020, 2021, and 2022 will be assessed and correlated to the CE and quality of the SOM. The data will be submitted to the normality test, exploratory analysis (Principal Component Analysis), analysis of variance, and test of means, Tukey P <0.05. (AU)