Climate Change Predicted to Negatively Influence Surface Soil Organic Matter of Dryland Cropping Systems in the Inland Pacific Northwest, USA

Summary

This field study quantified soil organic matter dynamics across a climatic gradient in dryland cropping systems of the inland Pacific Northwest and used climate projections to forecast future soil health. The research found that precipitation and temperature are more influential than management practices (tillage regime and cropping intensity) in determining soil organic matter levels. Climate projections through 2070 predict a rise in the MAT:MAP ratio, forecasting significant declines in surface soil organic matter and associated soil health indicators across the region.

UK applicability

The findings are moderately applicable to UK dryland and semi-arid arable systems, particularly in eastern regions with lower rainfall. However, the UK's higher mean annual precipitation and lower mean annual temperatures differ substantially from the inland Pacific Northwest, so direct extrapolation of projected soil organic matter declines should account for these regional climatic differences.

Key measures

Surface (0–10 cm) soil organic C and N; active and recalcitrant fractions of soil organic matter; mean annual temperature (MAT); mean annual precipitation (MAP); climate ratio (MAT:MAP)

Outcomes reported

The study measured surface soil organic carbon and nitrogen, and active and recalcitrant fractions of soil organic matter across long-term experiments under different tillage regimes and cropping intensities. Climate projections through 2070 were used to forecast declines in surface soil organic matter and soil health across the inland Pacific Northwest.

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