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

Summary

This experimental study examined how different types of sheep excreta application and soil organic matter content affect selenium uptake by perennial ryegrass, a key forage crop for ruminant nutrition. The results indicate that one-time applications of sheep urine and faeces did not enhance, and in several cases reduced, selenium concentration and accumulation in grass, with organic matter content and excreta type modulating biogeochemical processes affecting selenium availability. The authors conclude that direct animal supplementation is a more effective strategy than manure application for ensuring adequate selenium intake in ruminants.

UK applicability

These findings are directly relevant to UK grassland and sheep farming systems, where manure application and forage selenium status are important management considerations. The research suggests that current practice of using ruminant excreta to improve soil fertility may not reliably enhance forage selenium content, with implications for livestock supplementation strategies in organic and conventional UK farming.

Key measures

Selenium concentration in perennial ryegrass tissue (ICP-MS analysis); total selenium accumulation in grass; soil organic matter content; type and source of sheep excreta (urine, faeces, or combination); mineral supplementation type (organic vs. inorganic) in sheep feed

Outcomes reported

The study measured selenium concentration and total selenium accumulation in perennial ryegrass grown in soils of different organic matter contents after application of sheep urine and/or faeces. Results showed that excreta application either maintained or decreased selenium uptake by grass, with feces significantly reducing total selenium accumulation in high organic matter soil.

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