Cover crop management system and soil quality in relation to water erosion in olive orchards

Abstract

Soil quality plays a crucial role in the balance and productivity of agroecosystems while influencing the surrounding environment; however, its definition and quantification present significant challenges. To ensure effective soil management and conservation for future generations, a comprehensive definition of soil quality must encompass its multiple functions. Gaps remain in advancing soil quality assessments, particularly in production systems prone to rapid degradation due to water erosion, such as olive cultivation on tropical soils. This research aimed to evaluate soil quality and the effects of different cover crop systems in mitigating water erosion in tropical olive orchards. The first study assessed cover crop management effects on soil structure and microstructure using field analysis and micromorphology, revealing that the combination of olive trees with jack beans, followed by crowned and mown spontaneous vegetation, minimised soil loss over six years while improving soil structure, increasing A horizon thickness, and enhancing total porosity. The presence of illuvial clay film fragments highlighted the role of erosive forces in the detachment and redistribution of fine soil particles within the surface layer. The second study examined the relationship between electrical resistivity and soil water content across different landscape positions, demonstrating that electrical resistivity is a reliable tool for estimating soil moisture distribution in Inceptisols under tropical conditions. Specific calibration models for different land uses were developed with remarkable precision, allowing for the association of variations in resistivity (ρ) – or inferred water content (θ) – with distinct soil conservation management systems and their impact on the soil-plant system. The third study evaluated soil quality under different land uses, revealing a negative correlation between soil and water losses and soil quality indices. Cover crop management significantly improved soil quality and reduced water erosion, with spontaneous vegetation yielding the most favourable results, while olive trees on bare soil were highly susceptible to environmental degradation. Overall, the findings highlight the need for careful integration of cover crop management with olive tree growth to maximise soil conservation benefits.