Impact of selenium biofortification on production characteristics of forages grown following standard management practices in Oregon

Jean A Hall; Gerd Bobe; Shelby J Filley; Mylen G Bohle; Gene J Pirelli; Guogie Wang; T Zane Davis; Gary S Bañuelos

doi:10.3389/fpls.2023.1121605

Impact of selenium biofortification on production characteristics of forages grown following standard management practices in Oregon

Front Plant Sci. 2023 Mar 31:14:1121605. doi: 10.3389/fpls.2023.1121605. eCollection 2023.

Authors

Jean A Hall¹, Gerd Bobe^{2

3}, Shelby J Filley², Mylen G Bohle⁴, Gene J Pirelli², Guogie Wang⁴, T Zane Davis⁵, Gary S Bañuelos⁶

Affiliations

¹ Department of Biomedical Sciences, Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR, United States.
² Department of Animal and Rangeland Sciences, College of Agricultural Sciences, Oregon State University, Corvallis, OR, United States.
³ Linus Pauling Institute, Oregon State University, Corvallis, OR, United States.
⁴ Department of Crop and Soil Science, College of Agricultural Sciences, Oregon State University, Corvallis, OR, United States.
⁵ United States Department of Agriculture (USDA), Agricultural Research Service-Poisonous Plant Research Lab, Logan, UT, United States.
⁶ United States Department of Agriculture (USDA), Agricultural Research Service-San Joaquin Valley Agricultural Sciences Center, Parlier, CA, United States.

Abstract

Introduction: Low selenium (Se) concentrations in soils and plants pose a health risk for ruminants consuming locally-grown forages. Previous studies have shown that Se concentrations in forages can be increased using soil-applied selenate amendments. However, the effects of foliar selenate amendments applied with traditional nitrogen-phosphorus-potassium-sulfur (NPKS) fertilizers on forage yields, and nutrient contents, and agronomic efficiencies are unknown.

Methods: Using a split plot design, we determined the effects of springtime sodium selenate foliar amendment rates (0, 45, and 90 g Se ha^-1) and NPKS application (none, NPK for grasses/PK for alfalfa, and NPKS/PKS fertilization at amounts adapted to meet local forage and soil requirements) on forage growth and N, S, and Se concentrations, yields, and agronomic efficiencies. This 2-year study was conducted across Oregon on four representative forage fields: orchardgrass (Dactylis glomerata L.) in Terrebonne (central Oregon), grass-clover mixture in Roseburg (southwestern Oregon), and both grass mixture and alfalfa (Medicago sativa L.) fields in Union (eastern Oregon).

Results: Grasses grew poorly and were low in N content without NPK fertilization. Fertilization with NPK/PK promoted forage growth, increased forage N concentrations, and had to be co-applied with S when plant available S was low. Without Se amendment, forage Se concentrations were low and further decreased with NPKS/PKS fertilization. Selenate amendment linearly increased forage Se concentration without adversely affecting forage yields, N and S concentrations, or N and S agronomic efficiencies.

Discussion: Importantly, S fertilization did not interfere with Se uptake in Se amended plots. In conclusion, co-application of NPKS/PKS fertilizers and foliar sodium selenate in springtime is an effective strategy to increase forage total Se concentrations, while maintaining optimal growth and quality of Oregon forages.

Keywords: forage fertilization; grasses; legumes; nitrogen; selenium agronomic efficiency; selenium yield; sulfur.

Grants and funding

Funded in part by a grant from the Agriculture Research Foundation (G.J. Pirelli, Principal Investigator), Oregon State University, Corvallis, OR, USA, and by internal funds. The Central Oregon Hay Growers’ Association funded the harvesting costs for the Central Oregon (Terrebonne) site.