The uptake of selenium by perennial ryegrass in soils of different organic matter contents receiving sheep excreta

Summary

This study investigated how the application of sheep excreta to soils with varying organic matter contents affects selenium uptake by perennial ryegrass, a key determinant of ruminant selenium intake. Contrary to expectations, excreta application either maintained or decreased selenium concentrations in grass, with feces reducing total selenium accumulation in high organic matter soils, potentially through selenium sorption and microbial reduction. The findings suggest that direct selenium supplementation to animals is more effective than manure application for enhancing ruminant selenium nutrition.

UK applicability

The findings are directly relevant to UK grassland and sheep farming systems, where organic manure application is common practice. The results suggest that current reliance on animal excreta to improve forage nutritional status may not effectively address selenium deficiency in ruminants, informing mineral supplementation strategies on UK farms.

Key measures

Selenium concentration in plant tissue (ICP-MS analysis); total selenium accumulation in perennial ryegrass; soil organic matter content; excreta type (urine, feces, or both); mineral supplementation source (organic or inorganic)

Outcomes reported

The study measured selenium concentration and total selenium accumulation in perennial ryegrass grown in soils of different organic matter contents that received various types of sheep urine and/or feces. Biogeochemical reactions in soil were also examined to understand mechanisms affecting selenium availability.

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