Drought represents significant environmental stress, and improving agriculture water management and yield is a priority goal. The effect of diminishing soil water content in the grain filling (GF) stage, throughout physiological maturity (GM), on the yield and grain quality, leaf water potential (LWP), and maximum quantum yield (Fv/Fm) in four long photoperiod quinoa genotypes was evaluated in the South-Central zone of Chile, during the 2014–2015 and 2015–2016 seasons. Five irrigation treatments (T) were established. Irrigation was carried out when the available water (AW) of the root zone reached values of 100%, 70%, 40%, 20%, and 0%. The lowest LWP values were obtained by T20 and T0 (−1.95 MPa). The ‘Morado’ genotype reached the lowest LWP at both seasons, while the highest average LWP was achieved by the ‘AG 2010’ (2014–2015) and ‘Cahuil’ genotypes (2015–2016). A global trend of Fv/Fm values was observed from GF to GM: 0.74 toward 0.79 (2014/2015), and 0.74 toward 0.82 (2015/2016). Only during the second season, Fv/Fm showed differences among irrigation treatments. Total average grain yields in the second season (2.97 t ha⁻¹) were greater than those in the first season (1.43 t ha⁻¹). In both seasons, the ‘Cahuil’ genotype and T100 reached the highest yields. A significative decrease in yield was observed when AW diminished. A direct relationship between seed yield and leaf water potential (ΔY/ΔLWP) was found in all genotypes, varying between 5.53 (‘Cahuil’) and 2.86 t ha⁻¹ MPa⁻¹ (‘AG 2010’). Total proteins, albumins, and globulins varied between seasons, with almost no differences among irrigation treatments. Only the ‘Morado’ genotype showed a slight trend to obtain a higher content of total protein in both seasons. It is possible to grow quinoa under irrigation deficit conditions between GF throughout GM, maintaining yield parameters and nutritional quality.

Irrigation system design and irrigation management require appropriate classification of the soil and type of crop match. In Chile, agrological reports are currently being used to determine the homogeneity of soil units and land capability classes: fruit tree production vs orchard design. Agrological studies use a number of soil characteristics, but these do not include hydrophysical properties, which are essential when zoning for irrigation. Therefore, it is necessary to establish a methodology to objectively evaluate soils, based on a quantitative analysis that includes hydrophysical parameters. In this study, different methodologies are proposed for classifying homogenous soil units based on extensive field sampling. The field data was evaluated using two methodologies: 1) the SAG-USDA Manual and 2) in situ sampling of soil’s hydrophysical properties and pedotransfer models. There were differences between the methodologies regarding the zoning soil properties for irrigation system design and management. The methodology based on the SAG-USDA Manual requires auxiliary data in order to provide useful maps for design and management of irrigation systems. Published pedotransfer functions should be carefully assess before their use in large-scale design, as the quality the estimations depends on the data used to derive the equations. Therefore, if field data is available, we recommend calibrating equations using well-known statistical methods such as least square. In this study, the functions obtained describe the properties of interest properly, such as the field capacity for design of micro-irrigation systems. However, predicting wilting point did not give reliable results.

A large number of plastics are produced at the global level annually, and most end up in aquatic and terrestrial environments. Their extensive production and mismanagement have led to the accumulation of microplastics (MPs) in soils, posing concerns for human health and ecosystems. The aim of this study was to assess the presence of MPs in urban soils of the city of Chillán (Chile), in order to identify areas with higher concentrations. A systematic soil sampling covered the entire urban area of the city on a 500-m grid during January-February 2023. The sieved samples underwent MP extraction, identification, and classification using a stereo-electron microscope. Of the 174 sampling points evaluated, 95% contained MPs, with 68% in the form of plastic fibers and 32% in plastic fragments. The high prevalence of MPs found in the urban soil of Chillán indicates that urgent actions are needed to understand their environmental and health impacts.

Andean headwater catchments are key components of the hydrological cycle, given that they capture moisture, store water and release it for Chilean cities, industry, agriculture, and cities in Chile. However, knowledge about within-Andean catchment processes is far from clear. Most soils in the Andes derive from volcanic ash Andosols and Arenosols presenting high organic matter, high-water retention capacity and fine pores; and are very dry during summer. Despite their importance, there is little research on the hillslope hydrology of Andosols. Environmental isotopes such as Deuterium and 18-O are direct tracers for water and useful on analyzing water-soil interactions. This work explores, for the first time, the efficiency of cryogenic vacuum extraction to remove water from two contrasting soil types (Arenosols, Andosols) at five soil water retention energies (from −1500 to −33 kPa). Two experiments were carried out to analyse the impact of extraction time, and initial water content on the amount of extracted water, while a third experiment tested whether the cryogenic vacuum extraction changed the isotopic ratios after extraction. Minimum extraction times to recover over 90% of water initially in the soil samples were 40–50 min and varied with soil texture. Minimum volume for very dry soils were 0.2 mL (loamy sand) and 1 mL (loam). After extraction, the difference between the isotope standard and the isotopic values after extraction was acceptable. Thus, we recommend this procedure for soils derived from volcanic ashes.

Recently, the increasing concentration of people in urban areas has raised concerns about the geochemistry of trace and toxic elements in urban soil. Surface soil plays an important role in human exposure through ingestion, dermal contact, and inhalation. However, studies on urban soils associated with trace and toxic elements are quite limited in South America. This work presents the first geochemical approach to urban soil in the city of Chillán, Chile. The levels of As, Cu, Sr, and Zn were measured in topsoil (0-10 cm depth) samples (n = 174) collected across a 500-m grid, chosen to be representative of the entire urban area within the city. The hazard index (HI) and carcinogenic risk (CR) were used to assess the human health risk of trace and toxic elements. The mean concentrations for Cu, Zn, As, and Sr were 71.8, 229.8, 11.2, and 234.6 μg/g dw, respectively. The values of HI for children and adults present a descending order of Cu > Sr > Zn > As. The CR values of As, Cu, Sr, and Zn were within an acceptable range for both age groups. This information will be useful to implement plans to prevent possible human exposure to toxic compounds in urban environments in future landscapes.