Precision Estimation of Crop Coefficient for Maize Cultivation Using High-Resolution Satellite Imagery to Enhance Evapotranspiration Assessment in Agriculture

Authors: Qi Tang1, Hugo Delottier, Wolfgang Kurtz, Lars Nerger, Oliver S. Schilling, Philip Brunner

The estimation of crop evapotranspiration (ETc) is crucial for irrigation water management, especially in arid regions. This can be particularly relevant in the Po Valley (Italy), where arable lands suffer from drought damages on an annual basis, causing drastic crop yield losses. This study presents a novel approach for vegetation-based estimation of crop evapotranspiration (ETc) for maize. Three years of high-resolution multispectral satellite (Sentinel-2)-based Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), Normalized Difference Red Edge Index (NDRE), and Leaf Area Index (LAI) time series data were used to derive crop coefficients of maize in nine plots at the Acqua Campus experimental farm of Irrigation Consortium for the Emilia Romagna Canal (CER), Italy. Since certain vegetation indices (VIs) (such as NDVI) have an exponential nature compared to the other indices, both linear and power regression models were evaluated to estimate the crop coefficient (Kc). In the context of linear regression, the correlations between Food and Agriculture Organization (FAO)-based Kc and NDWI, NDRE, NDVI, and LAI-based Kc were 0.833, 0.870, 0.886, and 0.771, respectively. Strong correlation values in the case of power regression (NDWI: 0.876, NDRE: 0.872, NDVI: 0.888, LAI: 0.746) indicated an alternative approach to provide crop coefficients for the vegetation period. The VI-based ETc values were calculated using reference evapotranspiration (ET0) and VI-based Kc. The weather station data of CER were used to calculate ET0 based on Penman-Monteith estimation. Out of the Vis, NDWI and NDVI-based ETc performed the best both in the cases of linear (NDWI RMSE: 0.43 ± 0.12; NDVI RMSE: 0.43 ± 0.095) and power (NDWI RMSE: 0.44 ± 0.116; NDVI RMSE: 0.44 ± 0.103) approaches. The findings affirm the efficacy of the developed methodology in accurately assessing the evapotranspiration rate. Consequently, it offers a more refined temporal estimation of water requirements for maize cultivation in the region.

HGS-PDAF (version 1.0): A modular data assimilation framework for an integrated surface and subsurface hydrological model

Authors: Qi Tang1, Hugo Delottier, Wolfgang Kurtz, Lars Nerger, Oliver S. Schilling, Philip Brunner

This article describes a modular ensemble-based data assimilation (DA) system, which is developed for an integrated surface-subsurface hydrological model. The software environment for DA is the Parallel Data Assimilation Framework (PDAF), which provides various assimilation algorithms like the ensemble Kalman filters, nonlinear filters, 3DVar, and combinations among them. The integrated surface-subsurface hydrological model is HydroGeoSphere (HGS), a physically based modelling software for the simulation of surface and variably saturated subsurface flow, as well as, heat and mass transport. The coupling and capabilities of the modular DA system are described and demonstrated using an idealized model of a geologically heterogeneous alluvial river-aquifer system with drinking water production via riverbank filtration. To demonstrate its modularity and adaptability, both single- and multivariate assimilation of hydraulic head and soil moisture observations are demonstrated in combination with individual and joint updating of multiple simulated states (i.e., hydraulic heads and water saturation) and model parameters (i.e., hydraulic conductivity). The new DA system marks an important step towards achieving operational real-time management of coupled surface water-groundwater systems such as riverbank filtration wellfields based on integrated surface-subsurface hydrological models and data assimilation.

Defining sustainability in agricultural water management using a Delphi survey technique

Authors: Bishal Dahal, Tamara Avellán, Ali Torabi Haghighi, Bjørn Kløve

Sustainable water management measures are being developed to address the challenges posed by agriculture runoff and leaching on water resources. These measures are based on experts’ opinions from various sectors and disciplines, ensuring that all stakeholders’ perspectives are considered. For this, establishing a common understanding of ‘sustainability’ is essential to avoid misunderstandings, conflicts, and operational challenges. In this research, the Delphi survey technique was utilized to develop a definition of ‘sustainability’ in agricultural water management (SAWM) by considering the interdisciplinary group of experts from different parts of the world and those involved in a Horizon 2020 Research and Innovation Action. Twenty-six experts’ perspectives on environmental, economic, and social dimensions of sustainability were assessed, and identified key concepts included climate change, water quality, water availability, stakeholder participation, capacity building, subsidies, and incentives. These concepts were used to define sustainability for multi/interdisciplinary project settings. The definition was validated with consortium members of the project in the regular consortium-wide meetings and used in the respective deliverables dealing with sustainability. The results serve as a foundation for communication between the involved actors and the project’s definition of ‘sustainability.’ One recommendation from this work for broader policy formulation for SAWM in Europe is to prioritize farmer needs and focus on environmental sustainability.

Modeling of soil moisture and water fluxes in a maize field for the optimization of irrigation

Authors: Tamás Magyar, Zsolt Fehér, Erika Buday-Bódi, János Tamás, Attila Nagy

Precision irrigation is becoming more and more important in agricultural crop production due to the limited water resources resulting from the negative effects of climate change. Modeling of irrigation can support decision makers in the maintenance of the quantitative and qualitative parameters of the cultivated crops, while improving the efficiency of water consumption. In the present paper, a 3D hydrodynamic model was created in the HYDRUS environment to support the modeling of the temporal changes and spatial variations in the water balance (WB) of a maize cultivated Hungarian study site, thereby providing inputs for irrigation scheduling and variable rate irrigation for stakeholders. Beside soil physical parameters, crop evapotranspiration (ETc) values were also considered as model inputs for the phenological crop development stages of the maize from the sowing to the harvesting. This period was between the 3rd of May and the 10th of September in 2020 and the 20th of May and 14th of September for the year 2021. The performance of the model for soil moisture conditions were validated by on-field soil moisture measurements. The overall performance (full vegetation period) of the model was good (r2 = 0.88 for 2020 and r2 = 0.91 for 2021), but slightly varied among different phenological stages. Based on the model, the water balance of the investigated area was determined without any irrigation, alongside the cumulative water fluxes (CWF) through the boundaries including the root water uptake (RWU) of the maize as well. The results revealed that the incoming precipitation was not sufficient to supplement the water content in the soil to the optimal soil moisture range, except when the precipitation level is high enough to balance it. It was concluded that the water balance was negative for the investigated time periods without any irrigation. The specific water deficit (WD) values were calculated considering the area of the study site, which is 1439 m3/ha for 2020 and 2068 m3/ha for 2021. From the obtained results, optimal irrigation schedules were presented to keep the soil moisture content in the optimal range (20.92–14.41 V/V%) in the modeled area for two different vegetation periods. It was found that due to the irrigation the crop water productivity (CWP) increased by 6% and 4% in 2020 and 2021. Overall, the model is able to cope with changing circumstances that could help to mitigate the negative effects of climate change with the reasonable use of limited water resources in the future.

Comparing the environmental impact of poultry manure and chemical fertilizers

Authors: Nikolett Éva Kiss, János Tamás, Viktoria Mannheim, Attila Nagy

One of the challenges in livestock production is the significant volume of manure generated, which must be appropriately managed to mitigate its environmental impacts. Untreated manure poses a potential hazard to soil, surface water, groundwater, and human and animal health. Based on the life cycle assessment (LCA) method, the research aims to evaluate the ecological load of composted-pelletized poultry litter (CPPL) in maize and winter wheat production. Furthermore, the environmental loads of CPPL applications are compared with those of other N, P, and K fertilizers. The research study utilized the openLCA software with the Agribalyse 3.1 database to calculate eleven impact categories. In the case of maize, only ozone depletion has higher emissions. For winter wheat production, scenarios where the P fertilizer was MAP had lower impacts for NPK combinations. While for the CPPL, fuel was the main contributor to loads, for the NPK fertilizer scenarios, energy use for fertilizer production contributed more. The results can be relevant to the burdens of using different nutrient replacement products and creating diverse feed mixtures. The application of CPPL promises to reduce the burden of crop production and, consequently, feed production. Additionally, it allows for the recovery of manure not useable by the livestock industry.

Effects of Design and Operational Conditions on the Performance of Constructed Wetlands for Agricultural Pollution Control – Critical Review

Authors: Nan, X., Lavrnić, S., Mancuso, G., Toscano, A.

Constructed wetlands (CWs) can be considered as an efficient nature-based solution for the treatment of agricultural drainage water (ADW) and consequently for the mitigation of non-point source pollution. Aiming to provide suggestions for the construction and implementation of CWs, this paper proposes and discusses key parameters of CW design and operation. In order to verify the effect of these features, different case studies were reviewed, focusing on the performance of CWs that are treating agricultural drainage water. The findings showed that design and operational factors (e.g., the application of simple hydraulic structures and vegetation establishment) can improve pollutant removal efficiencies by increasing hydraulic retention time. Hydraulic efficiency of CWs can also be enhanced through certain shape characteristics (e.g., adoption of a high aspect ratio and creation of a long and narrow CW shape). The careful consideration of these parameters before and during CW implementation can therefore help these systems to achieve their full potential. However, further study is recommended to assess the effects of some parameters (e.g., flow direction and the application of deep zones).

Evaluation of new pivoting linear-move precision irrigation machine

Authors: Andrea SzabóJános TamásÁdám KövesdiAttila Nagy

Due to population growth, freshwater resources around the world are becoming increasingly scarce, and the water supply in agriculture has emerged as one of the limitations of food production. Variable-rate irrigation (VRI), a type of precision irrigation, allows water-efficient irrigation techniques to ensure an optimal water supply. The University of Debrecen, in collaboration with Magtár Kft., was the first in Hungary to develop a new laterally mobile irrigation machine equipped with VRI. The subject of our study was the testing of this system. According to the research, high and homogeneous irrigation uniformity was achieved in practice, with a Christiansen uniformity coefficient (CUc%) of 93 ± 2, distribution uniformity (DU%) of 88 ± 2 and coefficient of variation (CV) of 9 ± 2. Irrigation accuracy was also found to be satisfactory (mean absolute error 0.6 ± 0.1, mean bias error 0.2 ± 0.2, normalized root mean square error 8.6 ± 2), and only 1.4% ± 2% was overirrigated and 0.4% ± 0.3% underirrigated. In addition, the uniformity and accuracy of irrigation in different management zones along the pipeline were also investigated, and significant differences (p < 0.05) were found between irrigation water depths. Based on the above, a new laterally mobile irrigation machine equipped with VRI can be used to develop more uniform and accurate irrigation schedules in the future in arable fields as this is critical for water-saving irrigation management.

Quantification of water fluxes and soil water balance in agricultural fields under different tillage and irrigation systems using water stable isotopes

Authors: Alba Canet-Martí, Angela Morales-Santos, Reinhard Nolz, Günter Langergraber, Christine Stumpp

Sustainable agriculture should be based on management practices that improve resource usage efficiency and minimize harmful impacts on the environment while maintaining and stabilizing crop production. Both tillage and irrigation can have an influence on water resource usage and thus on hydrological processes within agroecosystems. However, it remains difficult to directly assess the effect of practices on water fluxes. Therefore, the objective of the study was to use oxygen and hydrogen isotopes (δ18O, δ2H) in the pore water of soil profiles as well as moisture contents for quantifying the soil water balance and fluxes. Covering all combinations, water content and isotope analysis in soil profiles were performed for 16 plots planted with winter wheat and managed with different tillage (conventional tillage (CT), reduced tillage (RT), minimal tillage (MT), and no-tillage (NT)) and irrigation systems (hose reel boom irrigation with nozzles (BI), sprinkler irrigation (SI), drip irrigation (DI) and no irrigation (NI)). The results indicated that the more intense the tillage, the lower the water content.
Among the irrigation systems, DI had the highest average water content. Tracing the isotope minimum of winter precipitation in pore water of soil profiles showed deeper percolation of water in the CT plots, which indicates higher water flow velocity for CT compared to other tillage variants. Considering both water content and water flow velocities resulted in average water fluxes ranging from 23 to 46 mm for six months (end of November to May). For the same time period, between 80% and 91% of the water contributed to evapotranspiration. The resulting evapotranspiration within tillage and irrigation variants decreased in the order CT>RT>MT>NT and SI>BI>DI>NI. Thus, the method revealed that the lower water content in CT fields is a consequence of both deeper water infiltration and higher evapotranspiration. Moreover, irrigation water contributed mostly to evapotranspiration, and drip irrigation showed the lowest evapotranspiration among irrigation systems. This study demonstrated that water stable isotopes can be used as indicators and are a promising method to quantify average water fluxes in agricultural fields with great potential for evaluating management practices.

Smart drainage management to limit summer drought damage in Nordic agriculture under the circular economy concept

Authors: Syed Md Touhidul Mustafa, Kedar Ghag, Anandharuban Panchanathan, Bishal Dahal, Amirhossein Ahrari, Toni Liedes, Hannu Marttila, Tamara Avellán, Mourad Oussalah, Björn Klöve, Ali Torabi Haghighi

Water excess and shortage (drought) are becoming more frequent phenomena that challenge the development of agriculture and crop production in Nordic countries. Indeed, water excess has been traditionally the main cause for crop failure in Nordic agriculture, and waterlogging causes substantial yield losses in this region (Bertholdsson,2013; Sundgren et al.,2018; Wiréhn,2018). In addition, drought in early summer, related to low snow conditions and early summer heatwaves occurring at crop water-sensitive stages, is a recurring phenomenon in the Nordic region. Lack of water causes substantial (10%–20%) irreversible yield losses of crops (Peltonen-Sainioet al.,2021), which undermine food production. For example, the 2018 summer drought in the Nordic region has reduced cereal yield by 40%–50% (Bakke et al.,2020; Beillouin et al.,2020; Statistiska-Meddelanden,2018). These challenges are amplified by the uncertainty and the expected long-term effect caused by climate change’s impact on hydrological variables like precipitation, temperature, and soil moisture (Putnam & Broecker,2017; Ruosteenoja et al.,2018;Vautard et al.,2013) as well as seasonal changes. The projected increase in precipitation in Northern Europe is mainly concentrated in winter and autumn, while precipitation is predicted to decrease in spring and summer (Chan et al.,2020; Rummukainen et al.,2004).Furthermore, global climate model projections show that the long-term mean soil moisture will decline in spring in northern Europe (Ruosteenoja et al.,2018), which can negatively affect agricultural crop production here.

Cost-benefit of green infrastructures for water management: A sustainability assessment of full-scale constructed wetlands in Northern and Southern Italy

Authors: Laura García-Herrero, Stevo Lavrnić, Valentina Guerrieri, Attilio Toscano, Mirco Milani, Giuseppe Luigi Cirelli, Matteo Vittuari

Sustainable water management has become an urgent challenge due to irregular water availability patterns and water quality issues. The effect of climate change exacerbates this phenomenon in water-scarce areas, such as the Mediterranean region, stimulating the implementation of solutions aiming to mitigate or improve environmental, social, and economic conditions. A novel solution inspired by nature, technology-oriented, explored in the past years, is constructed wetlands. Commonly applied for different types of wastewater due to its low cost and simple maintenance, they are considered a promising solution to remove pollutants while creating an improved ecosystem by increasing biodiversity around them. This research aims to assess the sustainability of two typologies of constructed wetlands in two Italian areas: Sicily, with a vertical subsurface flow constructed wetland, and Emilia Romagna, with a surface flow constructed wetland. The assessment is performed by applying a cost-benefit analysis combining primary and secondary data sources. The analysis considered the market and non-market values in both proposed scenarios to establish the feasibility of the two options and identify the most convenient one. Results show that both constructed wetlands bring more benefits (benefits-cost ratio, BCR) than costs (BCR > 0). In the case of Sicily, the BCR is lower (1) in the constructed wetland scenario, while in its absence it is almost double. If other ecosystem services are included the constructed wetland scenario reach a BCR of 4 and a ROI of 5, showing a better performance from a costing perspective than the absence one. In Emilia Romagna, the constructed wetland scenario shows a high BCR (10) and ROI (9), while the scenario in absence has obtained a negative present value indicating that the cost do not cover the benefits expected. Further research should be focused on improving ecosystem services monetary quantification from different context (i.e. rural vs urban).

A review of serious games for urban water management decisions: current gaps and future research directions

Authors: Aashna Mittal, Lisa Scholten, Zoran Kapelan

Urban water management (UWM) is a complex problem characterized by multiple alternatives, conflicting objectives, and multiple uncertainties about key drivers like climate change, population growth, and increasing urbanization. Serious games are becoming a popular means to support decision-makers who are responsible for the planning and management of urban water systems. This is evident in the increasing number of articles about serious games in recent years. However, the effectiveness of these games in improving decision-making and the quality of their design and evaluation approaches remains unclear. To understand this better, in this paper, we identified 41 serious games covering the urban water cycle. Of these games, 15 were shortlisted for a detailed review. By using common rational decision-making and game design phases from literature, we evaluated and mapped how the shortlisted games contribute to these phases. Our research shows that current serious game applications have multiple limitations: lack of focus on executing the initial phases of decision-making, limited use of storytelling and adaptive game elements, use of low-quality evaluation design and explicit indicators to measure game outcomes, and lastly, lack of attention to cognitive processes of players playing the game. Addressing these limitations is critical for advancing purposeful game design supporting UWM.

Comparison of simple models for total nitrogen removal from agricultural runoff in FWS wetlands

Authors: Alba Canet-Martí, Sabrina Grüner, Stevo Lavrnić, Attilio Toscano, Thilo Streck, Guenter Langergraber

Free water surface (FWS) wetlands can be used to treat agricultural runoff, thereby reducing diffuse pollution. However, as these are highly dynamic systems, their design is still challenging. Complex models tend to require detailed information for calibration, which can only be obtained when the wetland is constructed. Hence simplified models are widely used for FWS wetlands design. The limitations of these models in full-scale FWS wetlands is that these systems often cope with stochastic events with different input concentrations. In our study, we compared different simple transport and degradation models for total nitrogen under steady- and unsteady-state conditions using information collected from a tracer experiment and data from two precipitation events from a full-scale FWS wetland. The tanks-in-series model proved to be robust for simulating solute transport, and the first-order degradation model with non-zero background concentration performed best for total nitrogen concentrations. However, the optimal background concentration changed from event to event. Thus, to use the model as a design tool, it is advisable to include an upper and lower background concentration to determine a range of wetland performance under different events. Models under steady- and unsteady-state conditions with simulated data showed good performance, demonstrating their potential for wetland design.

Combined traffic control of irrigation on heterogeneous field

Authors: Andrea Szabó, Csaba Juhász, Bernadett Gálya Farkasné, Ádám Kövesdi, János Tamás, Attila Nagy

In arid areas, such as Hungary, most climate models forecast a rise in water scarcity. Irrigated land accounts for 2% of agricultural land in Hungary, with most irrigation technology being relatively outdated. The aim of this research was to lay the foundation for a combined traffic management system for a water-saving precision irrigation system on an 85-ha field in the Tisza River basin’s reference region. High-precision soil maps were created to support the water-efficient variable-rate irrigation system by selecting and selecting areas for different agrotechnical implementations and precision farming zones.

Investigation of Water Retention in Different Apple Orchards in North-Eastern Hungary

Authors: Norbert Szalacsi

As the frequency of weather extremes caused by global warming increases, the sustainability of the agricultural ecosystem is increasingly called into question. In some areas, both arable and horticultural production can no longer be imagined without irrigation. However, irrigation is not enough, as the quantity of water available is crucial for both agriculture and the maintenance of quality of life. The aim of this study is to investigate the effects of Vízőr (Water Retainer) on soil, to see how the amount of soil moisture present changes with different concentrations of the treatment and how soil moisture changes at different depths. The study used the internationally accepted soil sampling standard and statistical tests to determine that there was no significant difference in the condition before treatment (null condition), which represents the condition of the soil before treatment. SigmaPlot 12.0 was used to determine if there was a significant difference between the different treatments and the control. Using the field and laboratory tests, I generated a baseline and a post-treatment specific moisture profile, which will form the basis of the further investigations outside of this study. In the treatments, solutions of 25-fold and 50-fold dilutions were prepared according to the manufacturer’s recommendations and applied to the soils. Based on the results, it was confirmed that the treatments had a positive impact on the moisture content of the soil. Moisture content was higher for both 25-fold and 50-fold dilutions treatments for clay loam and biotope soils. And for the different depths, higher but not significant differences were observed for the 10 and 20 cm measurements. Although the results showed that more moisture was retained in the soil during the treatments, the analyses only covered the quantitative parameters. The data provide information on the amount of moisture present, but their availability is expected in further research.

Water balance calculation capability of Hydrological models – An overview

Authors: Hop Quang Tran, Zoltan Zsolt Fehér

Currently, in the world, there are many different hydrological models built and developed to solve problems related to the hydrological cycle. Each model has its specific mathematical foundati-ons to describe physical processes in nature. Therefore, each model has its various characteristics: set-ting up the model, input data requirements, model calibration and verification, and output results. Wa-ter balance is still playing an important role in the effective management and use of water resources for agriculture. Based on the results of the hydrological parameter’s calculation, the water balance of the study basin can be calculated by the user or by the separated module of each model. Each hydro-logical models have its advantages and disadvantages. However, it is impossible to simulate hydrologi-cal processes and water balance completely accurately in nature. Still, simulation results can give us a view of the changing trend of hydrological components and the water balance. Model developers are gradually completing the shortcomings and improving the efficiency and accuracy so that the model can simulate reality with the highest accuracy. This paper sets out to review the fifteen hydrological models currently widely used in the world. Within the frame of the present study, some models are only briefly introduced; the rest are considered in more detail, from more aspects, from specific examples so that readers can decide for themselves which model is suitable for their study area and simulation needs, especially in the identity of the complex and unpredictable impacts of climate change on the agricultural sector.

Influence of equilibration time, soil texture, and saturation on the accuracy of porewater water isotope assays using the direct H2O(liquid)–H2O(vapor) equilibration method

Authors: Devakunjari Vadibeler, Michael P.  Stockinger, Leonard I. Wassenaar, and Christine Stumpp

The hydrogen and oxygen stable isotopes of water (δ2H and δ18O) are powerful tracers for studying subsurface water flow processes, but the extraction of porewater from unsaturated soil is complex and laborious. The direct liquid–vapor equilibration method (DLVE) for isotope analysis overcomes this challenge by analyzing headspace vapor in isotopic equilibrium with the porewater under closed system conditions. However, the effect of the equilibration time, soil texture, and porewater saturation on isotopic results is not fully understood yet. We tested three differently textured, disaggregated soils (sandy, silty loam and clay) to assess how the equilibration time is impacted by (i) porewater saturation (100%, 80%, 60%, and 40%), and (ii) soil surface area. For all tests, the water loss through diffusion was negligible (<0.3%). The experiments showed that for disaggregated sandy soil, 24 h was a sufficient isotopic equilibration time regardless of water saturation level. Similarly, 24 h was sufficient for kaolinite samples with 100% saturation exhibiting little isotopic variance even after 168 h of equilibration. For saturated silty loam with 2% organic carbon content, 96 h was the optimal equilibration time, whereas saturated silty loam with 4% organic carbon content did not reach isotopic equilibrium by 168 h. The optimal equilibration time increased depending on whether soil samples were disaggregated or kept in a core cutter. Inconclusive results for silty soils with organic carbon revealed the need to further investigate the possible influence of organic carbon on the DLVE method.

Wheat Yield Forecasting for the Tisza River Catchment Using Landsat 8 NDVI and SAVI Time Series and Reported Crop Statistics

Authors: Attila Nagy, Andrea Szabó, Odunayo David Adeniyi and János Tamás

Due to the increasing global demand for food grain, early and reliable information on crop production is important in decision-making in agricultural production. Remote sensing (RS)-based forecast models developed from vegetation indices have the potential to give quantitative and timely information on crops for larger regions or even at farm scale. Different vegetation indices are being used for this purpose, however, their efficiency in estimating crop yield certainly needs to be tested. In this study, the wheat yield was derived by linear regressing reported yield values against a time series of six different peak-seasons (2013–2018) using the Landsat 8-derived Normalized Difference Vegetation Index (NDVI) and Soil Adjusted Vegetation Index (SAVI). NDVI- and SAVIbased forecasting models were validated based on 2018–2019 datasets and compared to evaluate the most appropriate index that performs better in forecasting wheat production in the Tisza river basin.

Impact of climate change on wetland ecosystems: A critical review of experimental wetlands

Authors: Shokoufeh Salimi; Suhad A.A.A.N. Almuktar; Miklas Scholz;

Climate change is identified as a major threat to wetlands. Altered hydrology and rising temperature can change the biogeochemistry and function of a wetland to the degree that some important services might be turned into disservices. This means that they will, for example, no longer provide a water purification service and adversely they may start to decompose and release nutrients to the surface water. Moreover, a higher rate of decomposition than primary production (photosynthesis) may lead to a shift of their function from being a sink of carbon to a source. This review paper assesses the potential response of natural wetlands (peatlands) and constructed wetlands to climate change in terms of gas emission and nutrients release. In addition, the impact of key climatic factors such as temperature and water availability on wetlands has been reviewed.

Impact of future climate scenarios on peatland and constructed wetland water quality: A mesocosm experiment within climate chambers

Water purification is one of the most essential services provided by wetlands. A lot of concerns regarding wetlands subjected to climate change relate to their susceptibility to hydrological change and the increase in temperature as a result of global warming. A warmer condition may accelerate the rate of decomposition and release of nutrients, which can be exported downstream and cause serious ecological challenges; e.g., eutrophication and acidification. The aim of this study is to investigate the effect of climate change on water quality in peatland and constructed wetland ecosystems subject to water level management. For this purpose, the authors simulated the current climate scenario base on the database from Malm ̈o station (Scania, Sweden) for 2016 and 2017 as well as the future climate scenarios for the last 30 years of the century based on the Representative Concentration Pathway (RCP) and different regional climate models (RCM) for a region wider than Scania County.

Response of the Peatland Carbon Dioxide Sink Function to Future Climate Change Scenarios and Water Level Management

Authors: Salimi S; Berggren M; Scholz M;

Stress factors such as climate change and drought may switch the role of temperate peatlands from carbon dioxide (CO2) sinks to sources, leading to positive feedback to global climate change. Water level management has been regarded as an important climate change mitigation strategy as it can sustain the natural net CO2 sink function of a peatland. Little is known about how resilient peatlands are in the face of future climate change scenarios, as well as how effectively water level management can sustain the CO2 sink function to mitigate global warming. The authors assess the effect of climate change on CO2 exchange of south Swedish temperate peatlands, which were either unmanaged or subject to water level regulation. Climate chamber simulations were conducted using experimental peatland mesocosms exposed to current and future representative concentration pathway (RCP) climate scenarios (RCP 2.6, 4.5 and 8.5). The results showed that all managed and unmanaged systems under future climate scenarios could serve as CO2 sinks throughout the experimental period. However, the 2018 extreme drought caused the unmanaged mesocosms under the RCP 4.5 and RCP 8.5 switch from a net CO2 sink to a source during summer. Surprisingly, the unmanaged mesocosms under RCP 2.6 benefited from the warmer climate, and served as the best sink among the other unmanaged systems. Water level management had the greatest effect on the CO2 sink function under RCP 8.5 and RCP 4.5, which improved their CO2 sink capability up to six and two times, respectively. Under the current climate scenario, water level management had a negative effect on the CO2 sink function, and it had almost no effect under RCP 2.6. Therefore, the researchers conclude that water level management is necessary for RCP 8.5, beneficial for RCP 4.5 and unimportant for RCP 2.6 and the current climate.

Hydraulic and Physical Properties of Managed and Intact Peatlands: Application of the Van Genuchten-Mualem Models to Peat Soils

Authors: Meseret Walle Menberu, Hannu Marttila, Anna-Kaisa Ronkanen, Ali Torabi Haghighi, and Bjørn Kløve

Undisturbed peatlands are effective carbon sinks and provide a variety of ecosystem services. However, anthropogenic disturbances, especially land drainage, strongly alter peat soil properties and jeopardize the benefits of peatlands. The effects of disturbances should therefore be assessed and predicted. To support accurate modeling, this study determined the physical and hydraulic properties of intact and disturbed peat samples collected from 59 sites (in total 3,073 samples) in Finland and Norway. The bulk density (BD), porosity, and specific yield (Sy) values obtained indicated that the top layer (030 cm depth) at agricultural and peat extraction sites was most affected by land use change. The BD in the top layer at agricultural, peat extraction, and forestry sites was 441%, 140%, and 92% higher, respectively, than that of intact peatlands. Porosity decreased with increased BD, but not linearly. Agricultural and peat extraction sites had the lowest saturated hydraulic conductivity, Sy, and porosity, and the highest BD of the land use options studied. The van Genuchten-Mualem (vGM) soil water retention curve (SWRC) and hydraulic conductivity (K) models proved to be applicable for the peat soils tested, providing values of SWRC, K, and vGM-parameters (α and n) for peat layers (top, middle and bottom) under different land uses. A decrease in peat soil water content of ≥10% reduced the unsaturated K values by two orders of magnitude. This unique data set can be used to improve hydrological modeling in peat-dominated catchments and for fuller integration of peat soils into large-scale hydrological models.

Diffuse Water Pollution from Agriculture: A Review of Nature-Based Solutions for Nitrogen Removal and Recovery

Authors: Giuseppe Mancuso; Grazia Federica Bencresciuto; Stevo Lavrnić; Attilio Toscano

The implementation of nature-based solutions (NBSs) can be a suitable and sustainable approach to coping with environmental issues related to diffuse water pollution from agriculture. NBSs exploit natural mitigation processes that can promote the removal of different contaminants from agricultural wastewater, and they can also enable the recovery of otherwise lost resources (i.e., nutrients). Among these, nitrogen impacts different ecosystems, resulting in serious environmental and human health issues. Recent research activities have investigated the capability of NBS to remove nitrogen from polluted water. However, the regulating mechanisms for nitrogen removal can be complex, since a wide range of decontamination pathways, such as plant uptake, microbial degradation, substrate adsorption and filtration, precipitation, sedimentation, and volatilization, can be involved. Investigating these processes is beneficial for the enhancement of the performance of NBSs. The present study provides a comprehensive review of factors that can influence nitrogen removal in different types of NBSs, and the possible strategies for nitrogen recovery that have been reported in the literature.

51. Real-time spectral information to measure crop water stress for variable rate irrigation scheduling

Authors: A. Nagy; A. Szabó; B. Gálya Farkasné; J. Tamás.

In recent years, the point measurements of water management properties have become widespread and the spatial heterogeneity of a field is important. Spectral analysis provides an opportunity to measure the water load of plants in real time under field conditions. Thus, NDVI data was recorded using different remote sensing methods and then compared the pigment and dry matter content of the plants with different statistical methods. NDVI values were higher in the irrigated area in all cases. The highest NDVI value was reached on 23 July in irrigated areas. Based on the descriptive statistics of the examined values, with the exception of the dry matter content, the standard deviation of the examined factors exceeded 20% in all cases, which indicates a greater heterogeneity of the variables.

Assessment of Capsicum annuum L. Grown in Controlled and Semi-Controlled Environments Irrigated with Greywater Treated by Floating Wetland Systems

Authors: Suhad A. A. A. N. Almuktar; Suhail N. Abed; Miklas Scholz; Vincent C. Uzomah

Accumulation of trace elements, including heavy metals, were evaluated in soil and fruits of chilli plants (Capsicum annuum L.) grown under both laboratory-controlled and semi-controlled greenhouse location conditions. Chilli plant biomass growth in different development stages and fruit productivity were evaluated and compared with each other for the impact of growth boundary conditions and water quality effects. Treated synthetic greywaters by different operational design set-ups of floating treatment wetland systems were recycled for watering chillies in both locations. Effluents of each individual group of treatment set-up systems were labelled to feed sets of three replicates of chilli plants in both locations. Results revealed that the treated synthetic greywater (SGW) complied with thresholds for irrigation water, except for high concentrations (HC) of phosphates, total suspended soils, and some trace elements, such as cadmium. Chilli plants grew in both locations with different growth patterns in each development stage. First blooming and high counts of flowers were observed in the laboratory. Higher fruit production was noted for greenhouse plants: 2266 chilli fruits with a total weight of 16.824 kg with an expected market value of GBP 176.22 compared to 858 chilli fruits from the laboratory with a weight of 3.869 kg and an estimated price of GBP 17.61. However, trace element concentrations were detected in chilli fruits with the ranking order of occurrence as: Mg > Ca > Na > Fe > Zn > Al > Mn > Cu > Cd > Cr > Ni > B. The highest concentrations of accumulated Cd (3.82 mg/kg), Cu (0.56 mg/kg), and Na (0.56 mg/kg) were recorded in chilli fruits from the laboratory, while greater accumulations of Ca, Cd, Cu, Mn, and Ni with concentrations of 4.73, 1.30, 0.20, 0.21, and 0.24 mg/kg, respectively, were linked to fruits from the greenhouse. Trace elements in chilli plant soils followed the trend: Mg > Fe > Al > Cr > Mn > Cd > Cu > B. The accumulated concentrations in either chilli fruits or the soil were above the maximum permissible thresholds, indicating the need for water quality improvements.


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