Understanding the chemistry of manganese fertilizers and glyphosate mixtures by using synchrotron X-ray spectrometry

Author(s)

Machado, Bianca de Almeida ; Feresin Gomes, Marcos Henrique ; de Almeida, Eduardo ; Otto, Rafael ; Kamogawa, Marcos Yassuo ; Pereira de Carvalho, Hudson Wallace

• Document type: Journal article
• Source: SN APPLIED SCIENCES; v. 2, n. 11, p. 12-pg., 2020-10-17.

Abstract

The spraying of tank mixtures with manganese (Mn) and glyphosate is a practical alternative to alleviate nutritional deficiency while controlling weeds. Thereby, this study investigates the chemical interactions between glyphosate and commercial sources of Mn, such as MnSO4, Mn-phosphite, Mn-EDTA, Mn-glycine, and MnCO3. Nearly 30% of the Mn supplied as MnSO4 and Mn-glycine precipitated with glyphosate, yielding a Mn:glyphosate solid complex with molar ratio of nearly 2:1, both presenting similar chemical environment. XANES analysis of the supernatants indicate no formation of Mn-glyphosate soluble complexes. The use of Mn-EDTA as well as the maintenance of the mixture pH below 2.5 prevented precipitation, while pH above 7 caused the formation of MnO(OH). In conclusion, the Mn source and the pH of the mixtures matter. The absence of Mn-glyphosate soluble complexes suggests that dissolved Mn and glyphosate are still able to accomplish their functions, however, the precipitation significantly decreases their active availability. (AU)

• FAPESP's process: 15/05942-0 - Shedding light on the metabolism of nanomaterials absorbed by plants with X-ray and vibrational spectroscopy
• Grantee: Hudson Wallace Pereira de Carvalho
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 18/13401-7 - X-ray spectroscopy unfolding the effects of glyphosate on soybean manganese foliar uptake
• Grantee: Bianca de Almeida Machado
• Support Opportunities: Scholarships in Brazil - Master