Prediction of the Nutrient Retention Capacity of the Rehabilitated Gemenc-Bdda-Karapancsa Floodplains

The GEF-WB Nutrient Reduction project aims to reduce the phosphorus inputs of the Black Sea from the Danube by means of different interventions. Hungary takes part of this project by enhancing the nutrient trapping capacity of the Gemenc and Beda-Karapancsa wetlands （GBK） which can be found on the premises of the Danube Drava National Park along the Danube River in Southern Hungary. Due to anthropogenic influences, less of small floods reach the oxbows of the area than some decades before which has a negative effect on the ecosystem. The objective of the study is to predict the nutrient reduction capacity of the Gemenc-B6da-Karapancsa water system and to make a proposal to increase this capacity. Although the floodplain vegetation has a huge nutrient intake capacity, this is limited by the fact that the floodplain is not always covered by the water of the river Danube. For that reason, a combination of hydrodynamic modelling, flood probability calculation and an estimation of suspended solids settling constitute the base of this study. The main course taken into account is the settling of suspended solids and the ratio of total nitrogen and total phosphorus to the mass of sediment is determined by local measurement results.

Effects of land-use and climate change on sediment and nutrient retention in Guizhou,China

Introduction:Sediment and nutrient retention have significant impacts on agricultural productivity and water quality.Obvious changes of climate and land-use have deeply affected freshwater ecosystem services in the last several decades.Nevertheless,it is unclear what the differences are in the impact of climate and land-use changes on freshwater ecosystem services.Outcomes:The impacts of climate and land-use change on sediment and nutrient retention(two essential freshwater ecosystem services)were evaluated with the help of the Integrated Valuation of Environmental Services and Tradeoffs(InVEST)model.The results from the study area suggest a decreasing trend in sediment and nutrient retention from 1995 to 2015 when climate and land-use were changed simultaneously.A decreasing trend in sediment retention and an increasing trend in nutrient retention were presented under scenario A(climate change from 1995 to 2015 with land-use unchanged),while the sediment exported and nutrient retention exhibited a decreasing trend except sediment retained under scenario B(land-use change from 1995 to 2015 with unchanged climate).Rainfall erosivity and soil erodibility were more sensitive to the output of sediment retention,while retention efficiency produced more of an effect on nutrient retention.Discussion and Conclusion:Climate change played a dominant role in the change in sediment retention,while land-use change had a more significant effect on nutrient retention change than climate change.The results of this study provide explicitinformation for land-use managers to reduce the negative effects associated with sediment and nutrient retention.

Embedded reservoir and constructed wetland for drinking water source protection:Effects on nutrient removal and phytoplankton succession

An embedded reservoir that provides an efficient nutrient removal system protects drinking water.However,embedded reservoirs are rarely used in eutrophic shallow lakes because of their undetermined nutrient retention efficiency and unknown effects by the phytoplankton community.In this study,we aim to investigate the nutrient retention and algae succession in an embedded reservoir and adjacent wetland from April 2017 to September 2018 in the eastern part of Lake Taihu,China.More than 40%of total phosphorus(TP)and 45%of particulate phosphorous entering the reservoir were retained semiannually,and the highest TP removal efficiency was achieved in the reservoir during autumn with an average value of 53.3%±9.9%.The overall nitrogen retention efficiency(21.7%±37.8%)was lower than that of TP(41.8%±27.8%).Similar trends were obtained in the wetland area.An important pathway for phosphorus removal is through particulate matter retention.Our study revealed that nutrient retention mechanisms in the reservoir were primarily via macrophyte absorption,particulate substance sedimentation,and prolonged water residence time.Consequently,the phytoplankton biomass(Chl-a)in the reservoir decreased(from 48.0 to 25.2μg/L)and water transparency improved,due to the decreased P level and transformation of the phytoplankton group into simple structures with good ecological status.Therefore,the combination of embedded reservoir and constructed wetland ecosystem can be used successfully to protect surface water.The results will be advantageous to groups seeking to preserve drinking water sources.

Influence of biochar on growth performances,yield of root and tuber crops and controlling plant-parasitic nematodes

Root and tuber crops are important sources of food and provide income for millions of people worldwide besides an observed high demand for organically produced harvests.Hence,recent attention has been given to utilizing biochar,a carbon-rich material produced from the pyrolysis of organic materials,which improves soil structure,water-holding capacity,and nutrient availability,as an amendment to produce organic root and tuber crops.These effects are caused by the formation of organic coatings on the surface of biochar,which decreases hydrophobicity and increases the ability to retain nutrients,acting as a slow-release mechanism delivering nutrients dependent on plant physiological requirements.However,comprehensive studies on the impact of biochar application on root and tuber crop growth,productivity,and effectiveness in eliminating soil parasites have not been extensively studied.Thus,the purpose of this review is to explore the use of biochar and biochar-based soil amendments and their potential applications for improving the growth,yield,and efficacy of controlling parasitic nematodes in a wide range of root crops.Most of the studies have investigated the effects of biochar on cassava,sweet potatoes,and minor root crops such as ginger and turmeric.It has been observed that biochar application rates(5-20 t ha^(−1))increase the vine length and the number of leaves,tubers,and tuber weight.The addition of biochar demonstrates the ability to control plant-parasitic nematodes in a rate-dependent manner.While biochar has shown promising results in improving crop growth and yield of limited root and tuber crops based on a few biochar types,ample opportunities are around to evaluate the influence of biochar produced in different temperatures,feedstock,modifications and controlling parasitic nematodes.

Biochar and Compost Increase Crop Yields but the Effect is Short Term on Sandplain Soils of Western Australia

Sandplain soils on the south coast of Western Australia have low inherent fertility, which is mainly due to poor nutrient retention caused by insufficient clay and organic colloidal material. Previous research has shown the benefits in nutrient levels and retention from adding clay to sandplain soils; however, there is almost no information on the addition of organic amendments. A field experiment was established at the Esperance Downs Research Station, Western Australian, in May 2010, to assess the effects of wheat straw(WS) and chicken manure(CM) biochars and compost with and without phosphorus(P) addition on soil properties and crop production over five growing seasons. The five seasons alternated between winter and summer crops. The CM and WS biochar and compost treatments significantly increased crop yields and P uptake in 3, 2 and 1 of the five seasons, respectively. The yield increases(P < 0.05) were no more than 8%. By the end of the third season, no differences in crop yields were found that could be attributed to the organic amendments. The addition of P increased crop yields in each winter cropping season. Phosphorus addition explained more than 30%of the variation in crop yields. Despite marginal P levels and summer drought conditions, arbuscular mycorrhizal root colonisation was not affected by the organic amendments. There were no significant interactions between the organic amendments and P addition in terms of crop yields, P uptake or P uptake efficiency. We conclude that much of the effect of the organic amendments was due to direct nutrient addition which dissipated over time.

Comparative efficacy of a phytogenic feed additive and an antibiotic growth promoter on production performance, caecal microbial population and humoral immune response of broiler chickens inoculated with enteric pathogens

The aim of this work was to compare the efficacy of a commercially available phytogenic feed additive(PFA) and an antibiotic growth promoter, which was bacitracin methylene disalicylate(BMD), on performance, nutrient retention, caecal colonization of bacteria and humoral immune responses against Newcastle disease in broiler chickens challenged orally with Salmonella enteritidis and Escherichia coli.One-day-old male Cobb 400 broiler chicks(n = 120) were fed with 1) a negative control(NC) diet, which is the basal diet without any added growth promoter, 2) a positive control(PC) diet, the basal diet supplemented with BMD, 500 mg/kg and 3) a diet supplemented with PFA(150 mg/kg) for 39 days and the birds were inoculated with S. enteritidis and E. coli on d 28. Supplementation of PFA improved body weight, feed conversion ratio, retention of N and crude fiber, increased fecal moisture content and decreased digesta transit time as compared with the NC and PC groups(P <0.01). Both the PC and the PFA was found to be equally effective in controlling the surge in numbers of Salmonella and E. coli following oral inoculation of these bacteria as compared with the NC group(P <0.05) at 24 h past inoculation. Caecal content analysis on d 39 indicated lower numbers of Salmonella, E. coli and Clostridium in the PC and PFA groups as compared with the NC group(P <0.05). The number of Lactobacillus in the PFA group was higher than those in the NC and PC groups(P <0.05). Humoral immune response,measured as hemagglutination inhibition titer against Newcastle disease, was better in the PC and PFA groups compared with the NC group(P <0.05) at d 21 but the difference did not last till d 39. The heterophil to lymphocyte ratio was narrower(P <0.001) and alkaline phosphatase activity was higher(P <0.01) in the PFA group as compared with the NC and PC groups on d 39. It was concluded that the PFA, which is animal, environment and consumer friendly, may be used as an effective replacement for common in-feed antibiotics like BMD to enhance broiler performance especially when the birds are exposed to heavy infections on fields.