Perennial alley cropping contributes to decrease soil CO₂ and N₂O emissions and increase soil carbon sequestration in...

Area of Science:

• Agricultural Science
• Soil Science
• Climate Change Mitigation

Background:

• Alley cropping offers sustainable farming by diversifying crops and mitigating climate change.
• Evaluating its short-term impact on soil greenhouse gas emissions and carbon content is crucial for Mediterranean orchards.

Purpose of the Study:

• To assess the effects of alley cropping with reduced tillage on soil CO2 and N2O emissions and total organic carbon (TOC).
• To compare almond monoculture with tillage (MC) against alley cropping with Capparis spinosa (D1) and Thymus hyemalis (D2).

Main Methods:

• Field experiment over two years in a Mediterranean almond orchard.
• Measured soil CO2 and N2O emissions, and soil TOC at the beginning and end of the study.
• Compared treatments: monoculture with tillage (MC), alley cropping with C. spinosa (D1), and alley cropping with T. hyemalis (D2).

Main Results:

• CO2 emissions correlated with soil temperature; N2O emissions showed no correlation.
• MC had significantly higher CO2 emissions (87 mg m-2 h-1) than D1 and D2 (69 mg m-2 h-1).
• Cumulative CO2 equivalent (CO2e) emissions were highest in MC. D2 showed the lowest CO2e per unit production due to high thyme yield.
• TOC increased significantly only in D2 (from 3.85 to 4.62 g kg-1).

Conclusions:

• Alley cropping with reduced tillage enhances agroecosystem productivity and reduces CO2 emissions.
• Evergreen alley crops like thyme are essential for short-term soil organic matter increases.
• Cropping strategy, including plantation density and crop coverage time, is key for increasing TOC.