Jesús Párraga

Climate change negatively affects agriculture, causing desertification, salinisation, and drought. The biochar hydroinfiltrator (ES Patent No.: ES2793448 B2) is a device that increases the capture of rainwater or irrigation water for crops by increasing infiltration rates. Biochar, produced via biomass pyrolysis, has emerged as a promising agricultural amendment, as it helps to optimise moisture retention and improve soil structure, key aspects for boosting crop yields. There is growing interest in microorganisms’ plant-growth-promoting activity (PGP) by carrying out different activities considered growth promoters. The aim of the present study is to evaluate the use of a biochar hydroinfiltrator as a promoter of microbial activity when it is used in soil. Metagenomic analysis of soils with and without the device reveals that genera Bacillus and Sphingomonas became particularly enriched in soils with hydroinfiltrators. Also, in order to understand the interaction between the uses of biochar together with bacteria PGP, an in vitro test was carried out. Two microorganisms, previously selected for their characteristics as plant growth promoters, were inoculated in soils with and without biochar and they grew better after 15 to 30 days of inoculation, showing major CFU counts. This combined strategy—biochar hydroinfiltrator and PGP bacteria—offers an innovative, eco-friendly approach to sustainable agriculture, particularly under drought stress.

Global warming due to climate change has increased the frequency of sand and dust storms that affect air quality and ecosystems in general, contributing to air pollution. The Sahara Desert is the most potent emitter of atmospheric dust. The atmosphere is an extreme environment and microorganisms living in the troposphere are exposed to greater ultraviolet radiation, desiccation, low temperatures and nutrient deprivation than in other habitats. The Iberian Peninsula, and specifically the Canary Islands—due to its strategic location—is one of the regions that receive more Saharan dust particles annually, increasing year after year, although culturable microorganisms had previously never been described. In the present work, dust samples were collected from three calima events in the Canary Islands between 2021 and 2022. The sizes, mineralogical compositions and chemical compositions of dust particles were determined by laser diffraction, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. Particle morphology and biological features were also studied by scanning electron microscopy (SEM-EDX) and confocal laser scanning microscopy (CLSM). The mineral–bacteria interactions were described from microscopic observations, which revealed the presence of iberulites and small neoformed kaolinite crystals in association with bacteria. This article defines the term “mineral atmospherogenesis” and its variant, “mineral bioatmospherogenesis”, through microbial interaction. This is the first described case of kaolinite produced through mineral bioatmospherogenesis. The bacterial growth in atmospheric dust was illustrated in SEM images, constituting a novel finding. Twenty-three culturable microorganisms were isolated and identified by 16S rRNA sequencing. Members of the phyla Pseudomonadota, Bacillota and Actinomycetota have been found. Some of these microorganisms, such as Peribacillus frigoritolerans, have Plant Growth-Promoting Rhizobacteria (PGPR) properties. Potential human pathogenic bacteria such as Acinetobacter lwoffii were also found. The presence of desert dust and iberulites in the Canary Islands, together with transported biological components such as bacteria, could have a significant impact on the ecosystem and human health.

En las regiones semiáridas, los períodos de sequía representan uno de los mayores desafíos para la agricultura. El Hidroinfiltrador o Dispositivo Infiltrador (DI) (Patente Española No. ES 2793448 A1) ayuda a reestablecer el equilibrio hídrico de los suelos. El DI tiene forma cilíndrica que permite su colocación vertical, enterrado parcialmente en el suelo alrededor de los árboles de cultivo, facilitando así la infiltración profunda de agua de lluvia, riego o escorrentía. Es especialmente útil en zonas áridas y semiáridas afectadas por largos períodos de sequía y fuertes tormentas. En una finca experimental de olivar ubicada en Baena (Córdoba), se instalaron 90 DI en olivos, dejando 10 árboles como control (sin DI). Los suelos de esta finca presentan una baja tasa de infiltración, lo cual reduce la eficacia de la precipitación y aumenta significativamente el riesgo de erosión hídrica. Para analizar los efectos del DI, se simuló una lluvia torrencial en la que se pasaron 600 litros de agua a través del DI instalado en un olivo 3 años antes del experimento. Mediante el método geofísico de Tomografía Eléctrica de Resistividad (ERT en sus siglas en inglés) y análisis directos de muestras de suelo tanto in situ como en laboratorio, se observó un considerable aumento de la humedad del suelo donde había DI. En comparación con los olivos control (sin DI), la humedad casi se triplicó gracias a la rápida penetración del agua en el suelo, evitando así la escorrentía y la erosión hídrica. Además, se registró un incremento del 211% en la producción de aceitunas y un aumento del 177% en el rendimiento graso. Los perfiles ERT mostraron que el agua que penetra en el suelo se acumula en la zona de raíces del olivo, alejada de la superficie, favorecida su distribución por las rutas preferentes creadas por las raíces. Esto evita una evaporación rápida durante las altas temperaturas de primavera y verano. En este estudio, se muestra cómo el uso del sistema de recolección de agua de lluvia con DI representa una mejora significativa en la gestión de los escasos recursos hídricos provocados por el cambio climático. Además, proporciona beneficios agronómicos y ambientales para los sistemas agrícolas mediterráneos de secano.