Application of ammonium to a N limited arable soil enriches a succession of bacteria typically found in the rhizosphere

Yendi Navarro-Noya Marco Luna_Guido Nele Verhulst Bram Govaerts Luc Dendooven (2022, [Artículo])

Crop residue management and tillage are known to affect the soil bacterial community, but when and which bacterial groups are enriched by application of ammonium in soil under different agricultural practices from a semi-arid ecosystem is still poorly understood. Soil was sampled from a long-term agronomic experiment with conventional tilled beds and crop residue retention (CT treatment), permanent beds with crop residue burned (PBB treatment) or retained (PBC) left unfertilized or fertilized with 300 kg urea-N ha-1 and cultivated with wheat (Triticum durum L.)/maize (Zea mays L.) rotation. Soil samples, fertilized or unfertilized, were amended or not (control) with a solution of (NH4)2SO4 (300 kg N ha-1) and were incubated aerobically at 25 ± 2 °C for 56 days, while CO2 emission, mineral N and the bacterial community were monitored. Application of NH4+ significantly increased the C mineralization independent of tillage-residue management or N fertilizer. Oxidation of NH4+ and NO2- was faster in the fertilized soil than in the unfertilized soil. The relative abundance of Nitrosovibrio, the sole ammonium oxidizer detected, was higher in the fertilized than in the unfertilized soil; and similarly, that of Nitrospira, the sole nitrite oxidizer. Application of NH4+ enriched Pseudomonas, Flavisolibacter, Enterobacter and Pseudoxanthomonas in the first week and Rheinheimera, Acinetobacter and Achromobacter between day 7 and 28. The application of ammonium to a soil cultivated with wheat and maize enriched a sequence of bacterial genera characterized as rhizospheric and/or endophytic independent of the application of urea, retention or burning of the crop residue, or tillage.

CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA AMMONIUM CROP RESIDUES WHEAT MAIZE TILLAGE SOIL

Bacterial communities in the rhizosphere at different growth stages of maize cultivated in soil under conventional and conservation agricultural practices

Yendi Navarro-Noya Bram Govaerts Nele Verhulst Luc Dendooven (2022, [Artículo])

Farmers in Mexico till soil intensively, remove crop residues for fodder and grow maize often in monoculture. Conservation agriculture (CA), including minimal tillage, crop residue retention and crop diversification, is proposed as a more sustainable alternative. In this study, we determined the effect of agricultural practices and the developing maize rhizosphere on soil bacterial communities. Bulk and maize (Zea mays L.) rhizosphere soil under conventional practices (CP) and CA were sampled during the vegetative, flowering and grain filling stage, and 16S rRNA metabarcoding was used to assess bacterial diversity and community structure. The functional diversity was inferred from the bacterial taxa using PICRUSt. Conservation agriculture positively affected taxonomic and functional diversity compared to CP. The agricultural practice was the most important factor in defining the structure of bacterial communities, even more so than rhizosphere and plant growth stage. The rhizosphere enriched fast growing copiotrophic bacteria, such as Rhizobiales, Sphingomonadales, Xanthomonadales, and Burkholderiales, while in the bulk soil of CP other copiotrophs were enriched, e.g., Halomonas and Bacillus. The bacterial community in the maize bulk soil resembled each other more than in the rhizosphere of CA and CP. The bacterial community structure, and taxonomic and functional diversity in the maize rhizosphere changed with maize development and the differences between the bulk soil and the rhizosphere were more accentuated when the plant aged. Although agricultural practices did not alter the effect of the rhizosphere on the soil bacterial communities in the flowering and grain filling stage, they did in the vegetative stage.

Community Assembly Functional Diversity Intensive Agricultural Practices Plant Microbiome CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA SUSTAINABLE AGRICULTURE TILLAGE SOIL BACTERIA MAIZE

Distribución de nuevos grupos funcionales de bromeliáceas epífitas en la Reserva de Calakmul, Campeche

Casandra Reyes García NARCY ANAÍ PEREIRA ZALDÍVAR CELENE MARISOL ESPADAS MANRIQUE Manuela de Jesús Tamayo Chim NAHLLELI CIVI CHILPA GALVAN ALFREDO DORANTES EUAN MARYPAZ RAMIREZ MEDINA LIGIA GUADALUPE ESPARZA OLGUIN LILIAN JUAREZ TELLEZ MONICA GONZALEZ JARAMILLO (2022, [Artículo])

Evaluamos cómo cinco grupos funcionales recientemente descritos para las epífitas (plantas que viven sobre otras) de la familia Bromeliaceae pueden utilizarse para describir cambios ambientales entre dos tipos de selva con diferente grado de conservación. Los grupos funcionales son: tanque (profundo) C3, tanque CAM, tanque somero, nebulofita y pseudobulbosas. Los primeros dos tipos dependen de altas cantidades de lluvia, los tanques someros se asocian al uso de rocío, las nebulofitas al uso de neblina y las pseudobulbosas presentan alta suculencia en sus hojas. La distribución de estos grupos revela cambios ambientales dentro de la Reserva de Calakmul.

BROMELIACEAE FOTOSINTESIS CAM NEBULOFITAS TANQUE TILLANDSIA BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA VEGETAL (BOTÁNICA) ECOLOGÍA VEGETAL ECOLOGÍA VEGETAL

UN PASEO POR TIJUANA: UNA REFLEXIÓN ETNOGRÁFICA SOBRE LA COTIDIANIDAD Y EL IMPACTO DE LAS CARAVANAS DE MIGRANTES EN TIJUANA, BAJA CALIFORNIA, MÉXICO.

Victor Vazquez Mariana Gutierrez (2022, [Artículo, Artículo])

Resumen:

El siguiente articulo presenta una reflexión antropológica y urbana centrada en la vida diaria y los principales problemas incluyendo: el impacto de las caravanas de migrantes, y cuestiones urbanas en Tijuana durante los años 2018 – 2021. En adición, el articulo aborda otros temas importantes como: el impacto de la pandemia del COVID-19, y los patrones socioculturales históricos desarrollados para sobrevivir las condiciones de desigualdad económica en Tijuana. A nivel metodológico, el articulo utilizó un enfoque cualitativo basado en experiencias de trabajo de campo que incluyeron observación participante y múltiples entrevistas realizadas a residentes durante distintas visitas a Tijuana, Baja California, México entre los años 2018-2021. Las conclusiones de este articulo presentan una reflexión para entender y hacer visible las condiciones de vida de los migrantes, los esfuerzos brindados por una organización de migrantes y el estilo de vida único y problemas urbanos contemporáneos desarrollados en la ciudad fronteriza de Tijuana.

Etnografia Estudios Urbanos Estudios Fromterizo Border studies Ethnography Tijuana HUMANIDADES Y CIENCIAS DE LA CONDUCTA HUMANIDADES Y CIENCIAS DE LA CONDUCTA

Climate-smart agricultural practices influence the fungal communities and soil properties under major agri-food systems

madhu choudhary ML JAT Parbodh Chander Sharma (2022, [Artículo])

Fungal communities in agricultural soils are assumed to be affected by climate, weather, and anthropogenic activities, and magnitude of their effect depends on the agricultural activities. Therefore, a study was conducted to investigate the impact of the portfolio of management practices on fungal communities and soil physical–chemical properties. The study comprised different climate-smart agriculture (CSA)-based management scenarios (Sc) established on the principles of conservation agriculture (CA), namely, ScI is conventional tillage-based rice–wheat rotation, ScII is partial CA-based rice–wheat–mungbean, ScIII is partial CSA-based rice–wheat–mungbean, ScIV is partial CSA-based maize–wheat–mungbean, and ScV and ScVI are CSA-based scenarios and similar to ScIII and ScIV, respectively, except for fertigation method. All the scenarios were flood irrigated except the ScV and ScVI where water and nitrogen were given through subsurface drip irrigation. Soils of these scenarios were collected from 0 to 15 cm depth and analyzed by Illumina paired-end sequencing of Internal Transcribed Spacer regions (ITS1 and ITS2) for the study of fungal community composition. Analysis of 5 million processed sequences showed a higher Shannon diversity index of 1.47 times and a Simpson index of 1.12 times in maize-based CSA scenarios (ScIV and ScVI) compared with rice-based CSA scenarios (ScIII and ScV). Seven phyla were present in all the scenarios, where Ascomycota was the most abundant phyla and it was followed by Basidiomycota and Zygomycota. Ascomycota was found more abundant in rice-based CSA scenarios as compared to maize-based CSA scenarios. Soil organic carbon and nitrogen were found to be 1.62 and 1.25 times higher in CSA scenarios compared with other scenarios. Bulk density was found highest in farmers' practice (Sc1); however, mean weight diameter and water-stable aggregates were found lowest in ScI. Soil physical, chemical, and biological properties were found better under CSA-based practices, which also increased the wheat grain yield by 12.5% and system yield by 18.8%. These results indicate that bundling/layering of smart agricultural practices over farmers' practices has tremendous effects on soil properties, and hence play an important role in sustaining soil quality/health.

Agriculture Management Fungal Community Diversity Indices Climate-Smart Agricultural Practices CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA AGRICULTURE TILLAGE CLIMATE-SMART AGRICULTURE SOIL ORGANIC CARBON

Planting rice at monsoon onset could mitigate the impact of temperature stress on rice–wheat systems of Bihar, India

Carlo Montes Anton Urfels Eunjin Han Balwinder-Singh (2023, [Artículo])

Rainy Season TIMESAT APSIM Agricultural Production Systems Simulator Climate Adaptation CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA RICE WHEAT MONSOONS WET SEASON CROP MODELLING CLIMATE CHANGE ADAPTATION

Association of specific expansins with growth in maize leaves is maintained under environmental, genetic, and developmental sources of variation

Francois Tardieu (2007, [Artículo])

Environmental Stimuli Expansins CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CELLS CROPS GENETIC ENGINEERING PROTEINS TISSUE EPIDERMIS ZEA MAYS

Conservation agriculture based sustainable intensification: India updates

ML JAT (2021, [Objeto de congreso])

CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CONSERVATION AGRICULTURE SUSTAINABLE INTENSIFICATION LAND MANAGEMENT TILLAGE PLANT ESTABLISHMENT BIOMASS WATER MANAGEMENT

Análisis de velocidad de soldadura robotizada para proceso MIG en acero1045 AISI

Carlos Eduardo Hernández Acero (2022, [Tesis de maestría])

Esta investigación denominada “análisis de velocidad de soldadura robotizada para proceso MIG en acero 1045 AISI” busca el desarrollo de un modelo matemático que permita, mediante parámetros conocidos, el cálculo de la penetración de soldadura en piezas unidas con proceso Metal Inert Gas (MIG). El objetivo se centra en buscar la combinación de valores paramétricos para la velocidad de soldadura, el voltaje y la corriente, los que se obtienen mediante la aplicación de un diseño experimental, que, ejecutadas en el proceso, pueda lograr una penetración de soldadura aceptable para la unión de la pieza. El modelo de superficie de respuesta aplicado fue un diseño de experimentos 2k con diseño central compuesto, y posteriormente el modelo se utilizó para estimar la velocidad de soldadura. Este diseño de experimentos se ejecutó por medio del programa estadístico Minitab versión 17. (Hernández Acero et al., 2022). Una vez teniendo la penetración de soldadura deseada en la pieza, se puede calcular la velocidad de soldadura necesaria para el cálculo de tiempo ciclo y utilizar los parámetros definidos de corriente y voltaje. Los valores de estos factores serán útiles para comenzar la programación del robot ya con la celda funcional y reducir el tiempo de arranque en automático (Hernández Acero et al., 2022).

This research, named “robotic welding speed analysis for MIG process in 1045 AISI steel”, seeks to develop a mathematical model that allow, through know parameters, the calculation of welding penetration in parts joined with Metal Inert Gas (MIG) process. The objective is focused on finding the combination of parametric values for robot welding speed, voltage and current, which are obtained through the application of a design of experiments, which, executed in the process, can achieve an acceptable welding penetration for the union of the part. The response surface model applied was a 2k design of experiments with central composite design, and subsequently the model was used to estimate the welding speed. This design of experiments was obtained using the statistical software Minitab version 17. (Hernández Acero et al., 2022). Once having the desired welding penetration in the part, it can calculate the welding speed necessary for the cycle time calculation and use the defined parameters of current and voltage to start programming the robot with the functional cell and reduce the time of startup (Hernández Acero et al., 2022).

Soldadura MIG Penetración Tiempo ciclo Velocidad de soldadura MIG welding Penetration Cycle time Welding speed INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS OTRAS ESPECIALIDADES TECNOLÓGICAS OTRAS OTRAS

Soil moisture content and maize grain yield under conventional and conservation agriculture practices - results of short term field tests in liselo, Namibia

Christian Thierfelder (2023, [Artículo])

This article focuses on the results from trials developed to monitor the short-term effects of conventionally tilled systems versus CA on soil quality and crop productivity under conditions of the major cropping systems in central, north-central and north-eastern regions of Namibia. Conventional tillage (CT), Minimum tillage (MT), Minimum tillage, mulch (MT-M), Minimum tillage, rotation (MT-R) and Minimum tillage, mulch and rotation (MT-MR) were the primary treatments tested. Significant differences (p≤0.000) among the treatments were observed in the 0-60 cm soil profiles where MT-M plots had the highest soil moisture content (39.8 mm, Standard Error of Mean 0.2815) over the study period. A significant difference (p=0.0206) in grain yield was observed in the second season with CT plots yielding the highest grain yield (3852.3 kg ha-1, standard error of mean 240.35). Results suggest that CA has the potential to increase water conservation and contribute to reduction of the risk of crop failure. Climate change driven degradation under conventional tillage necessitate alternative sustainable tillage methods. Conservation tillage methods and conservation agricultural practices that minimize soil disturbance while maintaining soil cover need to be adopted more locally as viable alternatives to conventional tillage.

Grain Yield Soil Moisture Content CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CONSERVATION AGRICULTURE CONVENTIONAL TILLAGE GRAIN YIELDS SOIL WATER CONTENT MAIZE