Nutrient removal effectiveness by riparian buffer zones in rural temperate watersheds: The impact of no-till crops practices

Riparian buffer zones have the potential to capture chemical contaminants and to mitigate detrimental side-effects in aquatic ecosystems derived from excess fertilizers used in agro-food production. No-till farming systems are well known agricultural practices and are widely used in temperate areas. In that regard, different settings and widths of riparian buffer zones (12, 24, 36, 48 and 60 m) with woody vegetation, shrubs or grasses were assessed. The methodology was comprised of the evaluation of a large number of experimental sites and the sampling was conducted after the first rain period and respective fertilizer applications. The results point to the fact that effectiveness is largely controlled by buffer zone width and vegetation type. Indeed, buffer zones with 60 m width composed of woody soils were more effective in phosphorus (99.9%) and nitrogen (99.9%) removal when compared to shrub (66.4% and 83.9%, respectively) or grass vegetation (52.9% and 61.6%, respectively) areas. Woody vegetation has deep rooting systems and woody soils have a higher content of organic matter when compared to grass and shrubs areas.