Soil changes under different land-uses in the Cerrado of Mato Grosso, Brazil

• Soil content and catchment water quality of Cerrado and croplands were examined.
• Land conversion reduced infiltration rates near the soil surface in areas under agricultural production.
• Snapshot water sampling showed strong seasonality in water quality parameters.
• Water quality parameters were affected by agricultural activities.
• Land conversion risks increased surface erosion and nutrient transport to streams.

This study aimed to (1) examine the effects of land-use change on the soils of natural Cerrado transformed to common croplands (soybean/cotton/maize rotation and sugarcane) and pasture and (2) indicate how agricultural production affects water quality across a meso-scale catchment. Land conversion caused significant reduction in infiltration rates near the soil surface (0–40 cm depth) of pasture (− 96%) and croplands (− 90% to − 93%). Soil aggregate stability was significantly lower in croplands than in Cerrado and pasture. Topsoil pH and nutrient concentrations were high in croplands and pasture. Soybean crops had extremely high extractable P concentrations (80 mg·kg− 1; 9 times greater than the natural background), whereas pasture N levels declined. Nutrient accumulation of N and P did not occur at deeper horizons for any land-use type. Snapshot water sampling showed strong seasonality in water quality parameters. Higher temperature, oxi-reduction potential (ORP), NO2−, and very low oxygen concentrations (< 5 mg·l− 1) and saturation (< 60%) were recorded during the rainy season. In contrast, remarkably high (up to 0.8 mg·l− 1) PO43 − concentrations were measured during summer. Water quality parameters were affected by agricultural activities at all sampled sub-catchments across the meso-scale catchment, regardless of stream characteristics (stream order, percentage of riparian vegetation, sub-catchment size); thus, no spatial trends were observed. Direct NO3− leaching appeared to play a minor role; however, water quality is affected by agricultural non-point sources, due to topsoil fertiliser inputs affecting the entire catchment, from small low order streams to the larger rivers of the modified catchment. In conclusion, land-use conversion has degraded soil physical properties, leaving cropland soils more susceptible to surface erosion with potential lateral nutrient transport to the stream network.