Nitrogen and Phosphorus Losses in a Rural Watershed Under No Tillage System in Southern Brazil
Year: 2025
Type: preprint
Abstract: Intensive production is sought by farmers but may harm sustainability, depending on management practices. No-Tillage System (NTS) is a conservation system and a paradigm in grain production in Brazil, but the quality of adoption is under question whilst water erosion regained strength, an underestimated issue among farmers. This study evaluated concentrations and losses of nitrogen (N) and phosphorus (P) fractions in streamwater of a rural watershed under NTS without terraces. Water was sampled daily, from December 2022 to November 2023, and losses were associated with monetary costs to replenish nutrients. Particulate forms predominated for N and P. Soluble N-NO 3 - prevailed over N-NH 4 + , but concentrations of both remained below critical environmental limit (CEL) for Brazil, while total P frequently exceeded CEL. Concentrations of N and P oscillated seasonally. The highest N losses were in October and November, and P losses peaked in August, October, and November, associated with heavy rainfall and/or low vegetative cover. Annual losses of 30.80 kg N ha -1 and 4.91 kg P ha -1 generated monetary losses of US$ 22.58 ha -1 and US$ 4.85 ha -1 , respectively. The predominance of particulate N and P and the excess of total P in streamwater proved that NTS had limited effectiveness to control surface runoff without complementary practices. P losses represented eutrophication risk and, along with N losses, caused monetary impact at watershed scale, which may help enlighten farmers on the need for additional conservation practices, such as infiltration terraces and cover crops during fallow periods.
Language: English
Subfield: Environmental Chemistry
Field: Environmental Science
Domain: Physical Sciences
Open Access status: gold
OpenAlex ID: W4413305253