Impacts of fallow conditions, compost and silicate fertilizer on soil nematode community in salt–affected paddy rice fields in acid sulfate and alluvial soils in the Mekong Delta, Vietnam

© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/)Avoidance of intensive rice cultivation (IRC) and soil amendments are potential practices to enhance soil properties. There is only limited information on the effects of reduced IRC and its mixture with compost or silicate fertilizer (Si) on the soil nematode community in salt–affected soils. This study aimed to assess the shifts of soil nematode community by reducing a rice crop from triple rice system (RRR) to a double rice system and mixed with compost or Si in paddy fields in acid sulfate soil (ASS) and alluvial soil (AL) in the Mekong Delta, Vietnam. Field experiments were designed with four treatments in four replicates, including RRR and a proposed system of double–rice followed by a fallow (FRR) and with 3 Mg ha–1 crop−1 compost or 100 kg ha–1 crop−1 Si. Soils were collected at harvest after the 2 year experiment, reflecting the fifth and third consecutive rice crop in RRR and FRR system, respectively. Results showed that reduced IRC gave a significant reduction in abundance of plant–parasitic nematodes (PPN), dominated by Hirschmanniella and increased abundance bacterivorous nematodes when mixed to compost and silicate fertilizer in ASS. In addition, reduced IRC increased nematode biodiversity Hill’s indices and reduced herbivorous footprint in ASS. Proposed system having compost or Si had strongly increased in bacterivorous and omnivorous footprints. Particularly, reduced IRC mixture with Si increased abundance of Rhabdolaimus, Mesodorylaimus and Aquatides, metabolic footprints (structure footprint, bacterivorous, omnivorous and predator) and diversity Hill’s N1 index in ASS. Our results highlighted that reduced IRC was a beneficial practice for decreasing abundance of PPN in salt-affected soils and increasing abundance of FLN in ASS. IRC mixture with compost or Si had potential in structuring the nematode communities with increasing biodiversity, trophic structure, and metabolic footprintsPeer reviewedFinal Accepted Versio

Increased Birth Weight Associated with Regular Pre-Pregnancy Deworming and Weekly Iron-Folic Acid Supplementation for Vietnamese Women

Low birth weight is an important risk factor for neonatal and infant morbidity and mortality and may impact on growth and development. Maternal iron deficiency anaemia contributes to intrauterine growth restriction and low birth weight. Hookworm infections and an iron-depleted diet may lead to iron deficiency anaemia, and both are common in many developing countries. A pilot program of deworming and weekly iron-folic acid supplementation for non-pregnant women aiming to prevent iron deficiency was implemented in northern Vietnam. We compared the birth weight of babies born to women who had had access to the intervention to babies born in districts where the intervention had not been implemented. The mean birth weight of the intervention districts' babies was 124 g more than the control districts' babies; the prevalence of low birth weight was also reduced. These results suggest that providing women with deworming and weekly iron-folic acid supplements before pregnancy is associated with increased birth weight in rural Vietnam. This intervention was provided as a health system integrated program which could be replicated in other at-risk rural areas. If so it could increase the impact of prenatal and antenatal programs, improving the health of both women and newborns

Panta Rhei benchmark dataset: socio-hydrological data of paired events of floods and droughts

As the adverse impacts of hydrological extremes increase in many regions of the world, a better understanding of the drivers of changes in risk and impacts is essential for effective flood and drought risk management and climate adaptation. However, there is currently a lack of comprehensive, empirical data about the processes, interactions, and feedbacks in complex human–water systems leading to flood and drought impacts. Here we present a benchmark dataset containing socio-hydrological data of paired events, i.e. two floods or two droughts that occurred in the same area. The 45 paired events occurred in 42 different study areas and cover a wide range of socio-economic and hydro-climatic conditions. The dataset is unique in covering both floods and droughts, in the number of cases assessed and in the quantity of socio-hydrological data. The benchmark dataset comprises (1) detailed review-style reports about the events and key processes between the two events of a pair; (2) the key data table containing variables that assess the indicators which characterize management shortcomings, hazard, exposure, vulnerability, and impacts of all events; and (3) a table of the indicators of change that indicate the differences between the first and second event of a pair. The advantages of the dataset are that it enables comparative analyses across all the paired events based on the indicators of change and allows for detailed context- and location-specific assessments based on the extensive data and reports of the individual study areas. The dataset can be used by the scientific community for exploratory data analyses, e.g. focused on causal links between risk management; changes in hazard, exposure and vulnerability; and flood or drought impacts. The data can also be used for the development, calibration, and validation of sociohydrological models. The dataset is available to the public through the GFZ Data Services (Kreibich et al., 2023, https://doi.org/10.5880/GFZ.4.4.2023.001)

The challenge of unprecedented floods and droughts in risk management

Risk management has reduced vulnerability to floods and droughts globally1,2, yet their impacts are still increasing3. An improved understanding of the causes of changing impacts is therefore needed, but has been hampered by a lack of empirical data4,5. On the basis of a global dataset of 45 pairs of events that occurred within the same area, we show that risk management generally reduces the impacts of floods and droughts but faces difficulties in reducing the impacts of unprecedented events of a magnitude not previously experienced. If the second event was much more hazardous than the first, its impact was almost always higher. This is because management was not designed to deal with such extreme events: for example, they exceeded the design levels of levees and reservoirs. In two success stories, the impact of the second, more hazardous, event was lower, as a result of improved risk management governance and high investment in integrated management. The observed difficulty of managing unprecedented events is alarming, given that more extreme hydrological events are projected owing to climate change3

Multicomponent, Enantioselective Michael–Michael-Aldol-β-Lactonizations Delivering Complex β‑Lactones

Optically active, tertiary amine Lewis bases react with unsaturated acid chlorides to deliver chiral, α,β-unsaturated acylammonium salts. These intermediates participate in a catalytic, enantioselective, three-component process delivering bi- and tricyclic β-lactones through a Michael–Michael-aldol-β-lactonization. In a single operation, the described multicomponent, organocascade process forms complex bi- and tricyclic β-lactones by generating four new bonds, two rings, and up to four contiguous stereocenters. In the racemic series, yields of 22–75% were achieved using 4-pyrrolidinopyridine as Lewis base. In the enantioselective series employing isothiourea catalysts, a kinetic resolution of the initially formed racemic Michael adduct appears operative, providing yields of 46% to quantitative (based on 50% max) with up to 94:6 er. Some evidence for a dynamic kinetic asymmetric transformation for tricyclic-β-lactone <b>1d</b> was obtained following optimization (yields up to 61%, 94:6 er) through a presumed reversible Michael

Catalytic Generation of Ammonium Enolates and Related Tertiary Amine-Derived Intermediates:Applications, Mechanism, and Stereochemical Models (n → π*)

Ammonium enolates are covalently bound, neutral zwitterionic enolates prepared by the reaction of tertiary amines and various electrophilic substrates including acid halides, α-halo carbonyls, and α,β-unsaturated carbonyls. The reaction mechanism was proposed to involve formation of chiral ammonium enolate, which is responsible for the chiral induction upon a-protonation. In 1999, Fu and coworkers investigated the enantioselective addition of alcohols to ketenes using their previously developed class of chiral Lewis bases, namely, enantioenriched 4-dimethylamino pyridines (DMAP) and pyrrolo ferrocenes. Based on the working mechanistic hypothesis that the reaction follows, a nucleophilic addition to ketene followed by a diastereoselective protonation of the intermediate ammonium enolate, several proton sources were studied. The study of ketene aminolysis raised the possibility of a proton transfer to generate a catalytically active Bronsted acid intermediate in the enantioselective alcoholysis of ketenes. Exquisite control of both absolute and relative stereochemistry of stereogenic carbon centers is crucial in modern polypropionate synthesis.</p

Does natural feed supply the nutritional needs of shrimp in extensive rice-shrimp ponds? – A stable isotope tracer approach

Rice-shrimp culture systems occur throughout Asia where there are seasonal alterations of fresh and saltwater availability. During the dry season, black tiger shrimp are grown at low densities, and in the wet season, rice, or rice and shrimp are grown together. Previous studies point to issues with suboptimal rice and shrimp production, due, in part, to climatic conditions driving changes in water quality, and pond management practices. However, the availability of natural benthic food supplies for shrimp production is less well studied. This study used a 15N‑nitrogen stable isotope tracer added to replicated enclosures within two rice-shrimp ponds to trace shrimp feeding on benthic natural biota. This experiment was conducted in both the wet and dry seasons. The 15N-ammonium rapidly enriched the 15N signature in the particulate organic matter (POM) in the water column, indicative of significant phytoplankton uptake of nitrogen (N). In contrast there was little enrichment of the benthic algae in the same time frame. After 13 d, most of the shrimp in the replicate enclosures had little or no 15N enrichment. This result occurred across both ponds and in both seasons. This suggests that enriched N was not transferred through the benthic food web to the shrimp. The results of the 15N enclosure experiments were combined with biomass estimates of benthic algae and macrobenthos, shrimp growth data, and linked to other parallel studies of water quality and sediment biogeochemistry in the same ponds. Overall, the findings point to inadequate feed stocks for shrimp, and hence the need to consider supplemental feeding with high quality formulated feeds in order to improve growth rates and survival