N use efficiencies and N ₂ O emissions in two contrasting, biochar amended soils under winter wheat—cover crop—sorghum rotation

Summary

This lysimeter-based field study examined slow pyrolysis wood chip biochar's effects on nitrogen cycling and emissions in temperate intensive agriculture using a multi-year crop rotation. Whilst biochar reduced N₂O emissions by 15% and leaching by 43% compared to controls, it produced no measurable improvement in nitrogen use efficiency, crop yield, or plant nitrogen uptake across either soil type. The findings suggest that whilst biochar offers some environmental benefits in temperate systems, it does not substantially enhance agronomic nitrogen performance under intensive fertilisation regimes.

UK applicability

These results are directly applicable to UK temperate arable farming, particularly in regions with intensive cereal rotations and high nitrogen inputs. The finding that biochar does not improve nitrogen use efficiency or yields under UK-type intensive management systems may temper expectations for biochar as a productivity-enhancing amendment, though modest emissions reductions could support climate mitigation goals.

Key measures

N fertiliser use efficiency (via ¹⁵N tracing), crop yield, plant N uptake, N₂O emissions, N leaching losses, soil type comparison (sandy loamy Cambisol vs silty loamy Luvisol)

Outcomes reported

The study measured nitrogen use efficiency, crop yields, nitrogen uptake, N₂O emissions, and nitrogen leaching losses in two contrasting soil types amended with wood chip biochar under a winter wheat–cover crop–sorghum rotation. Nitrogen fate was tracked using ¹⁵N-labelled fertiliser applied to winter wheat, with green rye as an intervening cover crop.

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