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

Summary

This lysimeter study evaluated slow pyrolysis wood chip biochar effects on nitrogen cycling in temperate soils under intensive fertilisation regimes. Whilst biochar reduced N2O emissions by 15% and leaching by 43% compared to controls, it produced no significant effects on nitrogen use efficiency, crop yields, or overall nitrogen cycling in the winter wheat–cover crop–sorghum rotation across two contrasting soil types. The findings suggest that biochar provides narrow environmental benefits in terms of greenhouse gas and nitrogen loss mitigation but does not substantially enhance agronomic performance in intensively managed temperate systems.

UK applicability

These findings are directly applicable to UK temperate arable farming, as the study used similar soil types (Cambisol and Luvisol) and crop sequences relevant to British agriculture. However, the results suggest that biochar amendment alone may not justify widespread adoption in the UK's intensive fertilisation systems if yield and nutrient uptake gains are limited, though the emissions and leaching reductions merit consideration in nitrate vulnerable zones.

Key measures

Nitrogen fertiliser use efficiency (15N-labelled ammonium nitrate tracking), crop yields, nitrogen uptake, N2O emissions, leaching losses, plant nitrogen recovery in winter wheat, cover crop (green rye), and sorghum

Outcomes reported

The study measured nitrogen use efficiency, crop yields, nitrogen-15 fate in plants and soil, nitrous oxide emissions, and nitrate leaching in a lysimeter experiment comparing biochar-amended and control soils across two soil types and a three-year crop rotation.

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