Impact of Nitrogen Sources on the Productivity and Nutritional Efficiency of Panicum maximum Cultivated under Crop-Livestock Integration in Sandy Soil.

• Grant number: 24/21246-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2025
• End date: April 30, 2026
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Marcelo Raphael Volf
• Grantee: Kaio Martins Pereira
• Host Institution: Pró-Reitoria de Pesquisa e Pós-Graduação. Universidade do Oeste Paulista (UNOESTE). Presidente Prudente , SP, Brazil

Abstract

Soybean-forage rotation is increasingly adopted in Brazil's agricultural regions, especially in sandy soils. This strategy has the potential to enhance the productivity of both grain crops and forages. Sustaining high forage yields in this system may depend on the use of fertilizers, particularly nitrogen. Therefore, this study aims to investigate the effectiveness of nitrogen (N) sources in the fertilization management of Megathyrsus maximus (syn. Panicum maximum) cv. Miyagui in sandy soils under rotation with soybean crops. The experiment will be conducted at the Experimental Farm of Universidade do Oeste Paulista (UNOESTE) in an area under a Crop-Livestock Integration (CLI) system during the 2024/2025 and 2025/2026 growing seasons. Seven nitrogen sources will be evaluated: (i) No application (Control), (ii) Urea (U), (iii) Coated Urea 1 (CU1), with potential N release at 0 - 30 - 60 days after application, (iv) Coated Urea 2 (CU2), with release at 30 - 60 days, (v) Coated Urea 3 (CU3), with release at 60 days, (vi) Composted Cattle Manure (CCM), (vii) Poultry Litter (PL), and (viii) Inoculation with Azospirillum brasilense (AZ). All sources classified as fertilizers will be applied at a rate of 120 kg ha¿¹ of N, while the AZ treatment will be applied superficially at 100 ml ha¿¹. The experimental design will follow a randomized block format with four replications and eight treatments (4x8). The parameters evaluated will include forage biomass, root system length and volume, nitrogen content in plants, and nitrogen losses through volatilization. Data will be analyzed using analysis of variance, with means compared using the LSD test (p<0.05). This study is expected to contribute to the development of nitrogen fertilization management strategies that mitigate nitrogen losses and promote the use of by-products from the livestock production chain. Such by-products, which are often environmental liabilities, could instead be repurposed for use on the farm