Soil N₂O emissions from specialty crop systems: A global estimation and meta‐analysis

Summary

This global meta-analysis of 1137 observations from 114 studies estimates soil N₂O emissions from specialty crop systems at approximately 1.5 Tg N₂O-N annually and identifies key drivers of emissions variation. The authors demonstrate that N fertiliser application increases N₂O emissions exponentially and that this effect intensifies under warmer, wetter conditions and with higher soil organic carbon. The analysis identifies drip irrigation, fertigation, and reduced tillage as effective mitigation strategies that can reduce emissions whilst maintaining or increasing crop yields, though trade-offs exist for deficit irrigation and non-legume cover crops.

Regional applicability

This global estimation provides context for UK specialty crop systems (particularly horticulture and intensive vegetable production), which typically operate with higher nitrogen inputs than extensive systems. The findings on management practices (drip irrigation, reduced tillage, fertigation) are directly applicable to UK glasshouse and field-vegetable production, though the meta-analysis does not isolate UK-specific data, and UK conditions (cooler, lower mean annual precipitation) may show different response magnitudes to N fertiliser than warmer regions in the dataset.

Key measures

Soil N₂O emission rates (Tg N₂O-N year⁻¹); effect sizes of N fertiliser application, irrigation type, tillage, cover crops, and biochar on N₂O emissions; relationships with mean annual temperature, precipitation, soil organic carbon, and soil pH

Outcomes reported

The study synthesised 1137 observations from 114 published studies to estimate global soil N₂O emissions from specialty crop systems at 1.5 Tg N₂O-N year⁻¹ (ranging 0.5–4.5 Tg N₂O-N year⁻¹) and evaluated the effects of agricultural management practices and environmental factors on N₂O emissions.

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