Development of a defined compost system for the study of plant-microbe interactions

Plant growth promoting rhizobacteria can improve plant health by providing enhanced nutrition, disease suppression and abiotic stress resistance, and have potential to contribute to sustainable agriculture. We have developed a sphagnum peat-based compost platform for investigating plant-microbe interactions. The chemical, physical and biological status of the system can be manipulated to understand the relative importance of these factors for plant health, demonstrated using three case studies: 1. Nutrient depleted compost retained its structure, but plants grown in this medium were severely stunted in growth due to removal of essential soluble nutrients - particularly, nitrogen, phosphorus and potassium. compost nutrient status was replenished with the addition of selected soluble nutrients, validated by plant biomass; 2. When comparing milled and unmilled compost, we found nutrient status to be more important than matrix structure for plant growth; 3. In compost deficient in soluble P, supplemented with an insoluble inorganic form of P (Ca3(PO4)2), application of a phosphate solubilising Pseudomonas strain to plant roots provides a significant growth boost when compared with a Pseudomonas strain incapable of solubilising ca3(PO4)2. Our findings show that the compost system can be manipulated to impose biotic and abiotic stresses for testing how microbial inoculants influence plant growth

Development of a defined compost system for the study of plant-microbe interactions

Plant growth promoting rhizobacteria can improve plant health by providing enhanced nutrition, disease suppression and abiotic stress resistance, and have potential to contribute to sustainable agriculture. We have developed a sphagnum peat-based compost platform for investigating plant-microbe interactions. The chemical, physical and biological status of the system can be manipulated to understand the relative importance of these factors for plant health, demonstrated using three case studies: 1. Nutrient depleted compost retained its structure, but plants grown in this medium were severely stunted in growth due to removal of essential soluble nutrients - particularly, nitrogen, phosphorus and potassium. Compost nutrient status was replenished with the addition of selected soluble nutrients, validated by plant biomass; 2. When comparing milled and unmilled compost, we found nutrient status to be more important than matrix structure for plant growth; 3. In compost deficient in soluble P, supplemented with an insoluble inorganic form of P (Ca3(PO4)2), application of a phosphate solubilising Pseudomonas strain to plant roots provides a significant growth boost when compared with a Pseudomonas strain incapable of solubilising Ca3(PO4)2. Our findings show that the compost system can be manipulated to impose biotic and abiotic stresses for testing how microbial inoculants influence plant growth

Impact des fumures organiques sur les rendements de la tomate et sur la densité des champignons à mycorhizes arbusculaires dans la zone de Saguiya (Niger)

La rhizosphère est très importante pour la croissance et les rendements des cultures et peut être affectée par des facteurs comme les pratiques agricoles ou les fertilisants. L’effet du type de fumure organique sur la densité des spores mycorhizogènes dans la rhizosphère de la tomate et sur les paramètres agronomiques a été évalué dans la zone de Saguiya (Niger). Le dispositif expérimental mis en œuvre comporte 48 parcelles traitées avec trois types de fumure organique (bouse de vache, bouse de chèvre et fumure de volaille) à trois niveaux de fertilisation (100%, 125% et 150%) en quatre replicats, pendant une campagne de trois mois. La variété de tomate exotique Tropimech a été cultivée avec suivi des paramètres agronomiques, et des échantillons du sol ont été prélevés pour l’extraction et le dénombrement des spores de champignons mycorhiziens arbusculaires (CMA). Le traitement T3 de l’essai 3 (soit 150% de la fiente de volaille plus matière organique) est le plus efficace parmi les traitements, avec 38 t ha-1 pour le rendement en fruits, 13 t ha-1 de rendement pour la partie foliaire et 6 t ha-1 pour la partie racinaire. Les principaux genres de spores CMA trouvés sont des Glomus sp, Gigaspora sp et Scutellospora sp. La densité de Scutelospora sp est aussi plus élevée pour le traitement avec fiente de volaille, avec une forte corrélation positive entre la densité des spores et les paramètres agronomiques. Les résultats ont montré que les fumures, en particulier la fiente de volaille, améliorent la fertilité du sol de cette région ainsi que la densité des spores CMA

Utilización de materiales compostados en la rehabilitación potencial de espacios afectados por residuos mineros y suelos de mina Use of compost for the restoration of mine wastes and mine soils

RESUMEN Una de las principales limitaciones para la rehabilitación de los impactos ambientales asociados a las actividades mineras es la falta de materia orgánica de los residuos mineros y los nuevos suelos originados tras la actividad. Por esta razón, el uso de enmiendas orgánicas, como lodos de depuradora, estiércoles o compost se ha extendido como una estrategia exitosa para la rehabilitación. En este artículo se expondrán los resultados de experiencias recientes en el uso de materiales compostados en rehabilitación de espacios afectados por actividades mineras. Los beneficios derivados del uso de compost incluyen la mejora de las propiedades físicas, químicas y biológicas de residuos mineros y suelos de mina desfavorables a los procesos de restauración. El incremento de materia orgánica asociado a la adición de compost provoca una mejora de la agregación que reduce la densidad aparente y aumenta la porosidad, reduciendo el riesgo de compactación y de erosión y mejorando la capacidad de retención de agua. Los valores de pH extremos son atenuados, al mismo tiempo que se incrementan las cantidades de nutrientes disponibles, especialmente N y P, y se reduce la biodisponibilidad de elementos potencialmente tóxicos. Finalmente, la introducción de poblaciones microbianas ausentes previamente conduce a la reactivación de los ciclos biogeoquímicos esenciales para el mantenimiento a largo plazo de la fertilidad y la sostenibilidad de los ecosistemas restaurados. Palabras clave: compostaje, suelos, residuos mineros, residuos orgánicos Use of compost for the restoration of mine wastes and mine soil

Water-dispersible clay in bare fallow soils after 80 years of continuous fertilizer addition

International audienceno abstrac

Mineralogy and modulus of rupture of roofing slate: Applications in the prospection and quarrying of slate deposits

The European norm UNE 12326 for roofing slate defines the mechanical properties of a slate tile through the Bending Strength test, which defines the modulus of rupture (MoR) of the tile. This MoR is related to the durability of the slate, and is one of its main commercial quality properties. During the prospection task previous to open a new slate quarry, it is crucial to define the MoR. The Bending Strength test needs proper slate tiles and a flexion press. To supply these slate tiles it is frequently necessary to open experimental quarry fronts, which are very expensive, and do not guarantee the viability of the quarry. Therefore, a method which could reduce the costs and time for the mechanical characterization would be very useful. In this work we have tried to relate the MoR to the mineralogical and petrographic characteristics of slate, using the Petrographic Examination test, also part of UNE 12326. This test contemplates the finding of a numerical index called Mica Stacking Index (MSI) which quantifies the mica layers fabric. We collected fifteen samples of roofing slates from the Northwest of the Iberian Peninsula and we studied them by using the Bending Strength and Petrographic Examination tests, plus mineralogical quantification using X-ray diffraction and measure of the illite crystallinity (Kubler Index) to determine the metamorphic grade. We have found a strong positive correlation between MoR values and MSI, and a negative correlation between MoR and Mica percentages. These correlations may be used to deduce the MoR, reducing costs during the exploitation labours in roofing slate mining, and also can be used in the quality controls on a working slate quarry