Impacts of soil use and management on water quality in agricultural watersheds in Southern Brazil

Abstract

Worldwide, agriculture is considered one of the main activities that influence water quality. The objective of this work was to evaluate the influence of soil use and management on water quality at the small watershed scale, in Southern Brazil. One watershed is characterized by production of annual crop seeds under no‐tillage (zero tillage), with crop rotation and with terraces (Sarandi watershed—SW), while the other is characterized by production of grains in the summer and pasture with grazing in the winter, under no‐tillage, without crop rotation and without terraces (Coxilha watershed—CW). Flow and climatic data were measured during 2 years. Water samples were manually taken at precipitation events and base flow over 1 year for laboratory analysis. During events of high volume, most of the rainfall was converted to base flow in SW, while in CW, most of the rainfall was transformed into overland flow. Overall, higher concentrations and losses of sediments and nutrients occurred in the CW, mainly during precipitation events in the winter crops season. Of the total nitrogen concentration in water, approximately 3% was ammonium‐N and 58% was nitrate‐N, on average, in both watersheds. For total phosphorus concentration in water, more than 75% was particulate in both watersheds, however, the bioavailable phosphorus accounted for 70% of the total phosphorus in the SW and for 35% in the CW. The higher concentration of bioavailable phosphorus in the SW indicates a short‐term pollution potential, but in both watersheds, the water quality was impaired by the high concentrations of total phosphorus. In general, even with no‐tillage, the results highlight the importance of best management practices as terracing, riparian vegetation, crop rotation, better crop systems and fertilizer management to avoid degradation of water resources.

Effects of riparian land use changes on soil attributes and concentrations of potentially toxic elements

“…The absence of riparian vegetation, inefficient soil use, and the change of soil physical and chemical attributes can decrease the ability of the riparian soil to function as a filter and, hence, increase the release of nutrients and contaminants into the other ecosystem compartments (Nguyen et al 2017, Gu et al 2019, Martíni et al 2021. Riparian vegetation increased 66, 84, and >80% water, sediment, and nutrient An Acad Bras Cienc (2021) 93(Suppl.…”

“…Anthropogenic phosphorus inputs into aquatic environments can accelerate eutrophication. Several authors have already shown the benefi ts of riparian vegetation for water, soil, and reduction of nutrient losses (Bortolozo et al 2015, Martíni et al 2021. However, the response of soil attributes to different anthropic uses remains a subject of research.…”

Willow (Salix babylonica) Extracts Can Act as Biostimulants for Enhancing Salinity Tolerance of Maize Grown in Soilless Culture

“…Globally, arable land is being rapidly lost or degraded because of shifts in land use due to urbanization and industrialization, climate change, salinization and acidification caused by wrong irrigation and fertilization practices, pollution and erosion [ 1 , 2 ]. Developing sustainable and eco-friendly crop production methods to feed the increasing population is a great challenge, which is closely associated with the sustainable development goals of the United Nations, including, but not limited to, zero hunger and poverty [ 3 ].…”