Cover crops improve the long‐term stabilization of soil organic carbon and total nitrogen through physico‐chemical protection in rainfed semiarid Mediterranean woody crop systems

Summary

This multi-site field study demonstrates that combining reduced or no tillage with cover crops—whether seeded or native—can improve long-term soil organic carbon and total nitrogen stabilisation in rainfed semiarid Mediterranean almond orchards, with effects mediated through physico-chemical protection via water-stable aggregates. Seeded cover crops accelerated stabilisation compared with native alternatives, though the magnitude of benefits varied substantially with local environmental and management conditions. The findings suggest that no-tillage as an isolated practice may be ineffective in compaction-prone soils, but is more promising when combined with complementary sustainable land management practices.

UK applicability

Whilst the study focuses on Mediterranean almond production under rainfed semiarid conditions, the mechanistic findings regarding cover crop integration and reduced tillage effects on soil carbon and nitrogen stabilisation through aggregate protection may have partial relevance to UK mixed farming and horticultural systems. However, the UK's higher rainfall, cooler temperatures, and different soil types mean direct translation of management prescriptions would require validation in UK edapho-climatic conditions.

Key measures

Soil organic carbon concentration and stocks; total nitrogen concentration; water-stable aggregate distribution; organic carbon and nitrogen pool fractionation; soil depth 0–20 cm; measurement period 5–12 years across five experimental sites

Outcomes reported

The study measured soil organic carbon (SOC) and total nitrogen (tN) stabilisation, water-stable aggregate distribution, and different organic carbon and nitrogen pools at 0–20 cm depth across five experimental sites in rainfed semiarid Mediterranean almond orchards. Comparisons were made between sustainable land management practices (reduced tillage with seeded or native cover crops, no tillage with native cover crops) and traditional farmer-managed tillage over 5–12 years.

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