Browsing by Author "Salazar, Osvaldo"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Accumulation of Sulphur in Atriplex nummularia Cultivated in Mine Tailings and Effect of Organic Amendments Addition
    (2019) Tapia, Yasna; Loch, B.; Castillo, Benjamín; Acuña Kohnenkamp, Edouard Jesús; Casanova, Manuel Antonio; Salazar, Osvaldo; Cornejo,Pablo; Antilén Lizana, Mónica
  • No Thumbnail Available
    Item
    Integrated crop-livestock farms have higher topsoil nitrogen and carbon than crop-only farms in Chilean Mediterranean climate volcanic soils
    (2025) Renwick, Leah L. R.; Celedon, Ayleen; Najera, Francisco; Espoz, Juan-Pablo Fuentes; Celedon, Daniela; Arellano, Claudia; Salazar, Osvaldo
    Context: Crop-livestock reintegration could reduce the environmental footprint of decoupled crop and livestock production related to biogeochemical cycles. Previous experiments showed that replacing fallow periods in annual crop rotations with grazed cover crops increases total nitrogen (N) and organic carbon (SOC), based on topsoil sampling and stocks compared by equivalent soil depth. Stock comparisons based on topsoil sampling or equivalent soil depth, rather than whole-profile sampling or equivalent soil mass, can erroneously report stock gains that have not occurred. Evidence of crop-livestock integration effects on commercial farms is needed. Objective: This study assessed on-farm if winter grass forages and beef cattle grazing in annual crop rotations lead to greater soil total N and SOC to a soil depth of 1 m. Methods: We sampled soil at eight paired commercial fields, four integrated crop-livestock (ICL) fields with grazed or ungrazed winter forage (annual ryegrass, oat) in the crop rotation (cereals, grain legumes, industrial crops), and four neighboring fields with winter fallow in the rotation, in volcanic soils in Nuble Region, central southern Chile, in fall 2022 and 2023. In each field, 10 soil cores were sampled from a 1 ha plot and separated into four depth layers (0-15 cm, 15-30 cm, 30-60 cm, and 60-100 cm). We quantified soil total N and SOC concentrations and stocks, on an equivalent soil mass basis, and soil texture throughout the soil profile. Results and conclusions: ICL sites had 10 % higher total N (+0.05 % N) and 8 % higher SOC concentrations (+0.5 % SOC) compared to paired non-ICL sites in the top 15 cm soil layer. The topsoil layer at ICL sites had 11 % higher N (+0.37 Mg N ha- 1 ) and 9 % higher SOC (+3.9 Mg SOC ha-1 ) stocks, based on an equivalent soil mass. Cumulative stocks below 15 cm to a depth of 1 m were similar between ICL and non-ICL sites. Across the 1 m soil profile, 52 % and 53 % of N and SOC stocks were below 30 cm depth. Significance: We provided on-farm evidence suggesting that integrating non-leguminous winter forages and grazing into annual crop rotations can retain N and store SOC in topsoil, with relevance to land managers and decision-makers who seek to build soil fertility and health through biodiversity and reduce N fertilizer use, though further research is recommended. Sampling soil to at least 60 cm depth can help capture management effects on N and SOC and quantify deeper N retention and SOC storage.
  • No Thumbnail Available
    Item
    Phytostabilization of trace elements and 13C isotope composition of Atriplex atacamensis Phil. cultivated in mine tailings treated with organic amendments
    (2023) Castillo, Benjamin; Acuna, Edouard; Sanchez, Andrea; Cornejo, Pablo; Salazar, Osvaldo; Tapia, Yasna
    Mining generates large quantities of mineral processing wastes that are typically stored in mine tailings (MT) ponds. Long-term exposure of the surrounding areas to the material from the tailings ponds has been reported to have adverse effects on both human health and the environment. The purpose of this study was to evaluate the ability of Atriplex atacamensis Phil. to phytostabilize metals (Cu, Fe, Mn, and Zn) and sulfur (S) when grown directly on mine tailings with and without compost (C) and humic substance (HS). The stress status of A. atacamensis Phil. was also evaluated through the C-13 isotopic composition of bulk leaves. A 120-day greenhouse experiment was conducted and three treatments were evaluated: (i) MT without any amendments (control), (ii) MT + C (dose: 89 ton ha(-1)), and (iii) MT + HS (0.72 ton ha(-1)). Mine tailings material exhibited low salinity, alkaline pH, high extractable S-SO4 concentrations, and low fertility; total Fe, Mn, and Zn concentrations were within the reference range for mine tailings, but total Cu concentrations were high at 1860 +/- 236 mg kg(-1). The HS had higher pH, EC, CEC, and available concentrations of N, P, and K than compost, while S-SO4 concentrations were similar in both amendments. C-13 NMR analysis showed that the HS contained more alkyl, aromatic, and phenolic groups, while the compost was dominated by O-alkyl and carboxyl groups. At the end of the experiment, the MT + C treatment achieved a significant decrease in Cu, Fe, and Mn concentrations in the roots and aboveground parts of A. atacamensis Phil. and an increase in Zn values in both tissues. Both amendments increased the sulfur content in the aboveground parts, while metal concentrations under the HS treatment proved similar to control. Furthermore, the delta(CV)-C-13-PDB values obtained in this study indicate that the organic amendments did not cause additional physiological stress to the plants compared to the MT treatment. Overall, A. atacamensis Phil. was shown to have the ability to phytostabilize metals and sulfur, making it a potential candidate species for in situ evaluation of the phytostabilization process on mine tailings.