Water, soil, and nutrient losses related to surface runoff in conventional and conservationist horticultural systems
Abstract
This study aimed to quantify the losses of water, soil, and nutrients through surface runoff during natural rainfall events and to evaluate different soil management systems for garlic cultivation. The experiment was conducted using a clayey Cambisol in 2023 and 2024. The crop sequence included cover crops before garlic during autumn/winter, followed by common beans in summer. The treatments included were as follows: (i) CT: conventional tillage with soil disturbance and no cover crops before garlic; (ii) BO: garlic over black oat residue; (iii) FR: garlic over forage radish; and (iv) WP: garlic over winter pea, with the three cover crops cultivated under a no-tillage (NT) system. The galvanized plates delimited the runoff area (4.25 m²), directing surface flow to the collectors. After each rainfall event, the losses of water, soil, total nitrogen (NT), total organic carbon (TOC), and soluble and total phosphorus (PSOL and PT, respectively) were determined. Water loss was 127% greater in 2023, with losses of NT, TOC, and PSOL being 84%, 21%, and 155% higher, respectively, than in 2024. Compared with the CT system, the NT system reduced soil loss by approximately 46%, regardless of the cover crop used. The greatest water, soil, and nutrient losses occurred in garlic (94%) in 2023 and in beans (74%) in 2024. The PT concentration in the runoff was 22 and 66 times higher than the limit specified under environmental legislation in 2023 and 2024, respectively. Cover crops effectively reduced soil losses but were less effective at mitigating water and nutrient losses through surface runoff. Annual climatic conditions are more relevant than crop management in nutrient transport by surface runoff in horticultural systems Cover crops reduce soil erosion but do not eliminate nutrient loss Soil preparation for garlic cultivation significantly increases soil loss Garlic yield is not negatively affected by the adoption of no-tillage farming