Coupling soil transfer from hillslope to riparian zone through natural fingerprint in a catchment with tobacco crop

Purpose Studies on soil provenance are important to evaluate the impacts generated in agricultural soil and in the micro basin environment intending to point out solutions to erosion control. This study has been accomplished to evaluate the soil transport in a hillslope where there is a tobacco crop and its connectivity with the riparian zone, correlating the location and depth profile of the samples with their chemical signature. Materials and methods Easy sample preparation, non-destructive analytical methods, and multivariate statistics for soil discrimination in different position and depths were performed for chemical element quantification. The micro basin studied is in the center of Parana State, in Brazil. Eleven soil profiles were sampled comprising hillslope, riparian zone, connection zone, and control area. The profiles were collected at five depths: 0–10, 10–20, 20–30, 30–40, and 40–50 cm. The analytical techniques applied were gamma spectrometry, to determine eU, eTh, K, and 137 Cs, and portable X-ray fluorescence spectrometry for Ca, Ti, Mn, Fe, Sr, and Zr quantification. Results and discussion 137 Cs was identified on the surface of the control area, confirming that this zone has not been disturbed since the last global fallout. Individual analysis per metal and principal component analysis (PCA) with the average values per depth and location were performed and interpreted together with the results of the 137 Cs. Samples collected in the connection area shows chemical similarity to the superficial samples of the riparian zone, either for the control area or the deposition zone. Conclusions The sediments generated by the tobacco crop have a similar chemical signature compared to the undisturbed soil for the analyzed natural elements. This is product of the natural pedogenesis process occurring in the toeslope micro basin riparian zone. The predominant influence in the PCA’s responses is related to the local topography. The chemical signature of the hillslope soil is changing while it moves to the deposition.