The Santa Lucia River basin provides drinking water to 60% of Uruguay population. The input of excessive amounts of nitrogen and phosphorus both from point and nonpoint sources could impair surface water quality and prevent its use for human consumption. The objective of this work was to evaluate surface water quality in small catchments under agricultural use located within this river basin. To this end, 5 streams and 4 small polders were surveyed between September 2008 and December 2009. The median concentrations of total phosphorus and total nitrogen in the streams across all sites and periods were 770 and 1659 µg L ⁻¹ , respectively, exceeding in the case of total phosphorus national and international thresholds. Furthermore, soluble phosphorous, the most readily available form to algae, represented 88.3% of total phosphorus. Concentrations of phosphorous and nitrogen in polders were also high. The eutrophication process of this water bodies could be linked to the intensive agricultural land use in the area because the nutrient input from cities and industries was not relevant in these catchments.

In this work, we evaluated the possibility of predicting the geographic origin of Uruguayan honeys using discriminant analysis (DA) on mineral concentration. Although the DA results appeared to discriminate between honeys from the south, central and north, the subsequent cross-validation analysis did not confirm this result. We also compared honeys from Uruguay and the Buenos Aires province (Argentina) using DA on mineral composition data. In this case, a clear difference between these two origins was observed. It seems possible to differentiate between Uruguayan honeys and those produced in a neighbouring country based on multivariate statistical methods.

Adopting no‐till (NT) after conventional tillage (CT) could affect surface runoff, but this effect may also depend on the rotation type, such as continuous grain crop (CC) or crop–pasture rotation (CP). The objective of this study was to assess the effects of soil‐tillage practices and rotation type on runoff in a long‐term field (LTF) trial established in 1993 on a Mollisol. This experiment was carried from 2012 to 2017 and included three tillage rotations (NT–CP, NT–CC, and CT–CP) and a natural pasture (NP) as a control, with three replications. Runoff was monitored under natural rainfall in microplots. The pasture of the CP treatment was rotationally grazed with dairy cows at high stocking rates before this experiment. We hypothesized that soil compaction by animal trampling during grazing would increase surface runoff regardless of tillage type. We measured the number of events and runoff depth in all treatments, grain yield, soil bulk density (BD), and infiltration rate (IR) in NT–CP and NT–CC. The results showed a statistically significant increase in average runoff (107 mm yr ^–1 ) for all rotations relative to NP (68 mm yr ^–1 ) and a significant difference for the mean of both CP rotations (119 mm yr ^–1 ) compared with NT–CC (83 mm yr ^–1 ). During the crop phase (excluding the pasture), the two NT rotations showed a similar trend, but with higher BD (1.23 g cm ^–3 ) and lower IR (27.2 mm h ^–1 ) for NT–CP. We concluded that animal trampling increased surface runoff regardless of tillage, but this effect would need to be confirmed at other sites.