Water infiltration and soil penetration resistance in long-term vegetable conservation cultivation

Context The no-tillage vegetable system (NTVS) is a form of regenerative agriculture. However, which cover crops (CCs) are most effective in improving soil physical properties in this system remains unclear. Aims This study evaluates whether improvements in water infiltration and soil penetration resistance (PR) in NTVS are influenced by CC diversification. Methods The experiment consisted of seven treatments with different levels of temporal and spatial diversification of CCs in no-tillage, plus a treatment under conventional tillage and low vegetation cover: NT-Ma, succession of onion and maize in vegetable no-tillage (NT); NT-Comt, commercial rotation and winter coverage and triennial onion in NT; NT-Gb, maize/winter grasses and biennial onion in NT; NT-La, legume in summer and annual onion in NT; NT-Ga, grass summer/winter and annual onion in NT; NT-LGa, legume summer/winter grass and annual onion in NT; CT-Ma, succession of onion and maize, in conventional tillage; and NT-Mixa, consortium (mix) of summer CCs and annual onion in NT. Soil assessments included PR (0–50 cm) and the water infiltration rate (double-ring infiltrometer method); the latter was also measured in an adjacent secondary forest area (dense ombrophilous forest), used as a reference. The biomass of the CCs and onion yield were determined. The analyses were conducted during the 2024/2025 growing season, 17 years after the trial establishment. The soil was classified as a Humic Dystrudept. Key results The greatest water infiltration occurred in the treatments with more frequent use of grasses (NT-Gb and NT-Ga) and in the treatment with single and recurrent use of velvet bean (NT-La). Infiltration in these treatments was similar to that of the secondary forest. The NT-La stood out for its reduction in PR. The system with the greatest spatial diversification of CCs (NT-Mixa) was the most efficient at increasing biomass production. However, onion yield was not affected by the amount or type of above-ground biomass. The differences in the physical properties of the soil were small compared with the good physical quality indexes observed across all treatments under NTVS. Conclusions In long-term no-till systems, the benefits of CCs on soil PR and water infiltration reached a saturation point. In this scenario, the predominant species type (e.g. legume or grass) and the approach to spatial or temporal diversification exerted minor influence on these variables. Implications The results demonstrate a high degree of flexibility in the selection of CC species in long-term no-till systems.