Concentration of soil-transmitted helminth eggs in sludge from South Africa and Senegal: A probabilistic estimation of infection risks associated with agricultural application.

Long-term effects of two organic amendments on bacterial communities of calcareous mediterranean soils degraded by mining.

Free-living nitrogen fixation (FLNF) by diazotrophs is a ubiquitous renewable resource and may constitute an attractive viable solution to the problem of environmental degradation caused by nitrogen over-fertilization. However, the biotic and abiotic control mechanisms of free-living nitrogen fixation are poorly understood. Moreover, there is rare information to link the composition and functions of diazotrophic communities; additionally, there are insufficient or inadequate predictors of the potential N fixation rate (PNFR) to help improve fertilization strategies. Here, through high-throughput sequencing, network analysis, and 15N2 labelling methods, we investigated the long-term effects of partial substitution of mineral N by organic fertilizers on diazotroph abundance and composition in double rice cropping systems. The field trial was conducted for 34 years and included five treatments: control without fertilizer (CK); only mineral NPK fertilizer (NPK); 70% inorganic N + 30% organic N + PK (NPKM1); 50% inorganic N + 50% organic N + PK (NPKM2); 30% inorganic N + 70% organic N + PK (NPKM3). Our results revealed that at the same nutrient input level, increasing the percentage of organic N substitution reduced diazotrophic abundance. Compared with the CK and NPK treatments, the organic substitution regimes reduced the fluctuation range of the PNFR between the early and late rice growing seasons. NH4+-N was the primary factor that negatively correlated (p

Predicting the influence of fertilization regimes on potential N fixation through their effect on free-living diazotrophic community structure in double rice cropping systems

Beneficial reuse of dam fine sediments as clinker raw material

Invasive plant species pose a global threat because they alter ecosystem functioning and biodiversity. The majority of plants form mutualistic mycorrhizal associations with mycorrhizal fungi, which contribute to the nutrient and water supply as well as diversity, competitive ability, and ecosystem productivity. In addition, the role of mycorrhizal interactions in plant invasiveness and the susceptibility or resistance of a habitat to invasion is increasingly recognized. However, the mechanisms by which mycorrhizae contribute to invasion remain unresolved. Here, we provide an overview of the empirical evidence and discuss the prospects for mycorrhizaemediated plant invasion. Overall, mycorrhizal fungi appear to have impacts on plant invasion that depend on the similarities between the mycorrhizal associations of the alien and native plants. We introduce plant mycorrhizal niche space (PMNS) as a plant’s ability to exploit and shape the mycorrhizal fungi pool of a habitat based on its dependency on mycorrhizal fungi, traits and priority effects. Collectively, the available evidence supports the idea that PMNS is independent of place of origin (invasive status). Understanding the drivers of the PMNS of both native and alien plant species may help to predict the potential invasiveness of plants and the invasibility of a habitat, to elucidate the role of the mycorrhizal fungal community in plant invasion and the impact of plant invasion on the structure of the mycorrhizal fungal community in new habitats (i.e., neighbour effect) and to improve restoration planning. In this regard, we highlight a number of knowledge gaps and discuss future research directions.

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The role of arbuscular mycorrhizal fungi in plant invasion trajectory

This article analyzed the survival of Escherichia coli, total coliforms, and Salmonella spp. in a soil amended with urban sewage sludge due to its potential use in soil rehabilitation and to the risk of microbial pollution. The survival of E. coli, total coliforms, and Salmonella spp. was determined in a soil amended with different doses of four different urban sewage sludge based on equivalent nitrogen fertilization of 0, 85, 170, and 340 kg N/ha. After the topsoil/sludge mixtures were made, they were wet to 18% moisture and analyzed for 2 months to determine the presence of bacteria, and then again after 1 year. The results indicate that the presence of microorganisms was strongly conditioned by the type of biosolid and the dose applied. Soil moisture diminished as the experiment progressed and seemed to play a role in controlling the presence of the bacteria. The initial concentrations of bacteria depend on the sewage sludge treatment. The evolution of E. coli had a similar trend as total coliforms, and Salmonella spp. was absent after 8 weeks although a positive presence was detected in some soils after a year. As a conclusion, long periods of time reduce the risk from the presence of pathogens in soils, and the persistence may be closely related to the treatment of sewage sludge and the initial amount of microorganisms in the sewage sludge.

Environmental consequences from the use of sewage sludge in soil restoration related to microbiological pollution

El uso de acolchados en suelos es una tecnica usada habitualmente en zonas aridas y semiaridas, para evitar los procesos erosivos y reducir la evaporacion del agua. En este estudio, se plantea un experimento para cuantificar el efecto de tres residuos organicos (hoja de palmera datilera triturada (Phoenix dactylifera), paja de cereal (heno) y corteza de pino), como materiales de acolchado, sobre la retencion de humedad de dos suelos de diferente textura, S1 (franco) y S2 (franco-limoso), saturados inicialmente con agua. Se emplearon recipientes de 31 x 31 cm de lado y 20 cm de altura, llenandose con suelo los primeros 15 cm. Los tratamientos se establecieron aplicando, a cada suelo, una capa de 2 cm de cada residuo organico, teniendo como referencia suelo sin acolchado. El experimento se realizo en invernadero, controlando los valores de Temperatura (T) y Humedad Relativa (HR) ambiente, hasta perdida total del agua inicial de los suelos. Se observo una elevada evaporacion en los suelos sin acolchado, en los primeros 16 dias, practicamente constante de 1813 g agua/dia x m2 en el suelo 1 y de 1792 g agua/dia x m2 en el suelo 2. Se establecieron regresiones lineales para cuantificar la perdida de agua con el tiempo, en cada tratamiento considerado. Los resultados demuestran que los tres subproductos organicos fueron efectivos para reducir la perdida de agua en ambos suelos, observandose diferencias estadisticamente significativas entre el uso de la corteza de pino y los otros dos materiales. La hoja de palmera tuvo una efectividad similar a la de la paja de cereal, por lo que se considera adecuada su utilizacion como acolchado en zonas como la nuestra, en las que por su abundancia, disponibilidad y facilidad de uso, supone un beneficio ambiental anadido.

https://dialnet.unirioja.es/descarga/articulo/6474602.pdf

Jose Ramón Rico Hernández

Papers

Environmental consequences from the use of sewage sludge in soil restoration related to microbiological pollution

Evaluation of plant waste used as mulch on soil moisture retention