Lucas Resmini Sartor a , Francisco Ruiz b , Priscilla Alves da Costa c , Daniel Pontes de Oliveira d , Ricardo Espíndola Romero c , Valdomiro Severino de Souza Júnior e , Marcelo Metri Corrêa f , Miguel Cooper b , Tiago Osório Ferreira b,g
- aDepartment of Agronomic Engineering, Federal University of Sergipe (DEAS – UFS), Rodovia Eng. Jorge Neto, km 3, Nossa Senhora da Glória, Sergipe CEP 49680000, Brazil
- bDepartment of Soil Science, University of São Paulo (ESALQ/USP), Av. Pádua Dias 11, Piracicaba, São Paulo CEP 13418-900, Brazil
- cDepartment of Soil Science, Federal University of Ceará (CCA/UFC), Av. Mister Hull s/n, Fortaleza, Ceará CEP 60021-970, Brazil
- dGeosolos Consulting Projects andServices LTDA, Fortaleza, Brazil
- eDepartment ofAgronomy, Federal Rural University of Pernambuco, Recife, Brazil
- fFederal University of Agreste of Pernambuco, Garanhuns, Pernambuco State 55292-270, Brazil
- gCenter for Carbon Research in Tropical Agriculture (CCARBON) – University of São Paulo, Piracicaba, São Paulo, Brazil
Highlights
- Irrigation induces clay mineral alteration through a mixed-layering process.
- Kaolinite and illite transform to smectite.
- Irrigation leads to enhanced cation exchange capacity and clay activity.
- Changes in micromorphology include shifts in soil structure and fabric types.
- Irrigation potentially alters fertility, carbon sequestration and water dynamics.
Abstract
Irrigation is crucial for improving crop productivity in dryland agricultural systems. As drylands are expected to expand due to future climate scenarios, understanding the effects of irrigation on soil properties for sustainable soil management is vital. In this context, our study investigates the impact of 23 years of irrigation on the soil morphology and mineralogy of a Eutric Calcaric Cambisol in the semi-arid region of Northeastern Brazil. Two soil profiles – one irrigated (IRR) and one non-irrigated (NIRR), located 40 m apart – were studied. Detailed mineralogical analyses, including thermogravimetric analysis and X-ray diffraction modeling, and micromorphological description of thin sections were conducted. Irrigation promoted an increase in proportion of smectite layers in the soil, as evidenced by the formation of a new mixed-layer clay phase (illite–smectite). This process was probably triggered by carbonate dissolution and subsequent cationic enrichment of the soil solution. As a result, there was an increase in soil cation exchange capacity (CEC), exchangeable sodium percentage (ESP), clay activity, and K+ and Ca2+ concentrations in IRR. Regarding soil micromorphology, irrigation induced changes in the relative c/f distribution, shifting from enaulic to porphyric. The granular and moderately developed subangular blocky structure shifted to a strongly developed subangular block structure with depth, while stipple-speckled fabrics changed to striated birefringent fabrics. Our results emphasize that an increase in irrigated croplands may reshape pedogenesis and soil fertility, consequently affecting soil functioning in these dryland soils.
Keywords
Micromorphology, Clay minerals, Mixed-layer minerals, Semi-arid climate, Calcaric Cambisol
