Submit to Water Review for Water Propose a Special Issue

Journal Menu

Journal Browser

Nitrogen Removal in Agricultural Watersheds: Through Agricultural Practices and Phytodepuration

Special Issue Editors
Special Issue Information
Keywords
Published Papers

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Water Quality and Contamination".

Deadline for manuscript submissions: closed (30 June 2020) | Viewed by 32472

Share This Special Issue

Special Issue Editors

Dr. Giuseppe Castaldelli

E-Mail Website1 Website2
Guest Editor

Department of Life Science and Biotechnology, University of Ferrara, Via L. Borsari, 46, 44121 Ferrara, Italy
Interests: nitrogen cycling; eutrophication; sustainable agriculture; phytodepuration; aquatic ecosystem restoration

Dr. Elisa Soana

E-Mail Website
Guest Editor

Department of Life Science and Biotechnology, University of Ferrara, Via L. Borsari, 46, 44121 Ferrara, Italy
Interests: eutrophication; biogeochemical functioning of freshwater ecosystems; nitrogen cycling; denitrification; phytodepuration; watershed nutrient budgets; water quality

Special Issue Information

Dear Colleagues,

In the last decades several studies from different disciplines have proven that the loss of reactive nitrogen from diffuse sources is one of the most serious threats to superficial and groundwater quality in industrialized and emerging countries, with multiple detrimental impacts on both ecosystems and human health. Notwithstanding this, eutrophication and groundwater nitrate contamination remain an unsolved issue and directives and international agreements have mostly failed to achieve the proposed amelioration goals.

The high performance of modern agriculture has been boosted by enhancing the amount of nitrogen fertilizer and the efficiency of irrigation. The latter has been made possible through the hydraulic streamlining of more and more ecologically simplified canal networks. In most cases, this has corresponded to the quantitative removal of aquatic vegetation and thus the loss of related ecosystem services, such as nitrogen removal via denitrification. On this view, it is not too speculative to hypothesize cascading effects to transitional and coastal zones, often underestimated or not considered at all, due to the reduction of denitrification capacity at the catchment scale.

To promote effective nitrogen excess mitigation strategies, we have to reconsider both the pathways of nitrogen load generation in watersheds and the buffer mechanisms in hydraulic networks. There are open questions concerning the parameters regulating denitrification in soil–aquifer systems, relative measurement methods, and the parameters regulating N removal via denitrification through microorganism–plant interactions in aquatic environments (i.e. drainage networks, wetlands, lagoons).

The general aim of this Special Issue is thus to add experimental and synthesised knowledge on the regulation of buffering capacity against nitrogen loads, both in groundwater and superficial waters. This calls for thematic and multidisciplinary contributions from a wide range of disciplines (e.g. biogeochemistry, hydrogeology, agronomy, engineering, environmental sciences, economy, etc.) focused on the following topics: regulation and parametrization of depuration capacity in drainage networks and its integration with modern canal management; insights on nitrogen retention/removal mechanisms in soil–aquifer systems, in relation to the specificity of hydrological regimes and agricultural and irrigation practices; economic analysis of the above-cited phenomena, with reference to eutrophication effects in terminal water bodies.

Prof. Dr. Giuseppe Castaldelli
Dr. Elisa Soana
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

Agricultural watersheds
Nitrate pollution
N retention
Drainage networks
Aquatic vegetation

Published Papers (10 papers)

Download All Papers

Order results

Result details

Show export options Show export options

Select all

Export citation of selected articles as:

Research

29 pages, 5310 KiB

Open AccessArticle

Reach-Scale Model of Aquatic Vegetation Quantifies N Fate in a Bedrock-Controlled Karst Agroecosystem Stream

by Nolan L. Bunnell, William I. Ford, Alex W. Fogle and Joseph Taraba

Water 2020, 12(9), 2458; https://doi.org/10.3390/w12092458 - 01 Sep 2020

Cited by 2 | Viewed by 2203

Abstract

In-stream fate of nutrients in karst agroecosystems remains poorly understood. The significance of these streams is recognized given spring/surface water confluences have been identified as hotspots for biogeochemical transformations. In slow-moving streams high in dissolved inorganic nutrients, benthic and floating aquatic macrophytes are recognized to proliferate and drastically impact nutrient fate; however, models that quantify coupled interactions between these pools are limited. We present a reach-scale modeling framework of nitrogen dynamics in bedrock-controlled streams that accounts for coupled interactions between hydrology, hydraulics, and biotic dynamics and is validated using a multi-year, biweekly dataset. A fluvial N budget with uncertainty was developed to quantify transformation dynamics for the dissolved inorganic nitrogen (DIN) pool using a GLUE-like modeling framework, and scenario analyses were run to test for model function over variable environmental conditions. Results from a 10,000 run uncertainty analysis yielded 195 acceptable parameter sets for the calibration period (2000–2002), 47 of which were acceptable for the validation period (2003) (Nash-Sutcliffe Efficiency (NSE) > 0.65; percent bias (PBIAS) < ±15), with significantly different posterior parameter spaces for parameters including denitrification coefficients and duckweed growth factors. The posterior solution space yielded model runs with differing biomass controls on DIN, including both algae and duckweed, but suggested duckweed denitrifies at a rate that would place the bedrock agroecosystem stream on the high-end of rates reported in the literature, contradicting the existing paradigm about bedrock streams. We discuss broader implications for watershed-scale water quality modeling and implementation strategies of management practices for karst agroecosystems, particularly with respect to stream restoration. Full article

(This article belongs to the Special Issue Nitrogen Removal in Agricultural Watersheds: Through Agricultural Practices and Phytodepuration)

► Show Figures

Figure 1

15 pages, 1023 KiB

Open AccessArticle

Introducing Life Cycle Assessment in Costs and Benefits Analysis of Vegetation Management in Drainage Canals of Lowland Agricultural Landscapes

by Elena Tamburini, Elisa Soana, Mauro Monti, Elisa Anna Fano and Giuseppe Castaldelli

Water 2020, 12(8), 2236; https://doi.org/10.3390/w12082236 - 08 Aug 2020

Cited by 2 | Viewed by 2788

Abstract

Nitrate pollution remains an unsolved issue worldwide, causing serious effects on water quality and eutrophication of freshwater and brackish water environments. Its economic costs are still underestimated. To reduce nitrogen excess, constructed wetlands are usually recognized as a solution but, in recent years, interest has been raised in the role of ditches and canals in nitrogen removal. In this study, we investigated the environmental and economical sustainability of nitrogen removal capacity, using as a model study a lowland agricultural sub-basin of the Po River (Northern Italy), where the role of aquatic vegetation and related microbial processes on the mitigation of nitrate pollution has been extensively studied. Based on the Life Cycle Assessment (LCA) approach and costs and benefits analysis (CBA), the effectiveness of two different scenarios of vegetation management, which differ for the timing of mowing, have been compared concerning the nitrogen removal via denitrification and other terms of environmental sustainability. The results highlighted that postponing the mowing to the end of the vegetative season would contribute to buffering up to 90% of the nitrogen load conveyed by the canal network during the irrigation period and would reduce by an order of magnitude the costs of eutrophication potential. Full article

(This article belongs to the Special Issue Nitrogen Removal in Agricultural Watersheds: Through Agricultural Practices and Phytodepuration)

► Show Figures

Figure 1

15 pages, 3275 KiB

Open AccessArticle

Modeling Soil Nitrate Accumulation and Leaching in Conventional and Conservation Agriculture Cropping Systems

by Nicolò Colombani, Micòl Mastrocicco, Fabio Vincenzi and Giuseppe Castaldelli

Water 2020, 12(6), 1571; https://doi.org/10.3390/w12061571 - 31 May 2020

Cited by 15 | Viewed by 2836

Abstract

Nitrate is a major groundwater inorganic contaminant that is mainly due to fertilizer leaching. Compost amendment can increase soils’ organic substances and thus promote denitrification in intensively cultivated soils. In this study, two agricultural plots located in the Padana plain (Ferrara, Italy) were monitored and modeled for a period of 2.7 years. One plot was initially amended with 30 t/ha of compost, not tilled, and amended with standard fertilization practices, while the other one was run with standard fertilization and tillage practices. Monitoring was performed continuously via soil water probes (matric potential) and discontinuously via auger core profiles (major nitrogen species) before and after each cropping season. A HYDRUS-1D numerical model was calibrated and validated versus observed matric potential and nitrate, ammonium, and bromide (used as tracers). Model performance was judged satisfactory and the results provided insights on water and nitrogen balances for the two different agricultural practices tested here. While water balance and retention time in the vadose zone were similar in the two plots, nitrate leaching was less pronounced in the plot amended with compost due to a higher denitrification rate. This study provides clear evidence that compost addition and no-tillage (conservation agriculture) can diminish nitrate leaching to groundwater, with respect to standard agricultural practices. Full article

(This article belongs to the Special Issue Nitrogen Removal in Agricultural Watersheds: Through Agricultural Practices and Phytodepuration)

► Show Figures

Figure 1

17 pages, 3700 KiB

Open AccessArticle

Effects of Changing Fertilization since the 1980s on Nitrogen Runoff and Leaching in Rice–Wheat Rotation Systems, Taihu Lake Basin

by Yaqin Diao, Hengpeng Li, Sanyuan Jiang and Xinyan Li

Water 2020, 12(3), 886; https://doi.org/10.3390/w12030886 - 21 Mar 2020

Cited by 7 | Viewed by 2590

Abstract

The nitrogen (N) loss associated with intensive agricultural activities is a significant cause of eutrophication and algal blooms in freshwater ecosystems. Taihu Lake has experienced serious surface water quality deterioration and eutrophication problems since the 1980s. The objective of this study is to examine the effect of fertilization changes since the 1980s on the N loss with runoff and leaching in the rice–wheat cropping rotation system. According to the results published in the literature since the 1980s, we set up four fertilization scenarios—N1980s: a fertilization rate of 350 kg N·ha⁻¹·year⁻¹ with 30% in manure fertilization to simulate fertilization in the 1980s; NA1990s: a fertilization rate of 500 kg N·ha⁻¹·year⁻¹ with 10% in manure fertilization to simulate fertilization in the early 1990s; NL1990s: fertilization rate of 600 kg N·ha⁻¹·year⁻¹ with 10% in manure fertilization to simulate fertilization in the late 1990s; and N2000s: fertilization rate of 550 kg N·ha⁻¹·year⁻¹ with all chemicals to simulate fertilization in the 2000s. Then, we calibrated and validated the DNDC (denitrification–decomposition) model through field experiments in two rice–wheat rotation seasons from November 2011 to October 2013 and simulated the N loss with runoff and leaching since the 1980s. The results show that N losses with leaching in the four periods (N 1980s, NA1990s, NL1990s, and N2000s) were 5.2 ± 2.1, 9.4 ± 3.2, 14.4 ± 4.6 and 13.5 ± 4.6 kg N·ha⁻¹·year⁻¹, respectively. N losses with surface runoff were 7.9 ± 3.9, 18.3 ± 7.2, 25.4 ± 10.2, and 26.5 ± 10.6 kg N·ha⁻¹·year⁻¹, respectively. The total N loss through runoff and leaching showed an increasing trend from 1980 to the late 1990s, when it reached its peak. The increase in N export to water due to fertilizer application occurs mainly during the rainy season from March to August, and especially from June to August, when rainfall events and intensive rice fertilization activities are frequent. After the 1990s, when the fertilizer rate was above 500 kg N·ha⁻¹·year⁻¹, the crop yields no longer increased significantly, which indicates that the optimized fertilization rate to balance crop yields and N loss to water is lower than 500 kg N·ha⁻¹·year⁻¹. The increase in fertilizer use has been unnecessary since the early 1990s, and at least about 30% of the N loss could have been prevented without reducing crop yields. Full article

(This article belongs to the Special Issue Nitrogen Removal in Agricultural Watersheds: Through Agricultural Practices and Phytodepuration)

► Show Figures

Figure 1

21 pages, 2734 KiB

Open AccessArticle

Vegetated Ditch Habitats Provide Net Nitrogen Sink and Phosphorus Storage Capacity in Agricultural Drainage Networks Despite Senescent Plant Leaching

by Jason Taylor, Matthew Moore, Shannon L. Speir and Sam Testa III

Water 2020, 12(3), 875; https://doi.org/10.3390/w12030875 - 20 Mar 2020

Cited by 12 | Viewed by 3253

Abstract

The utility of vegetated ditch environments as nutrient sinks in agricultural watersheds is dependent in part on biogeochemical transformations that control plant uptake and release during decomposition. We investigated nitrogen (N) and phosphorus (P) uptake and release across four P enrichment treatments in ditch mesocosms planted with rice cutgrass (Leersia oryzoides) during the summer growing and winter decomposition seasons. Measured N retention and modeled denitrification rates did not vary, but P retention significantly increased with P enrichment. At the end of the growing season, root biomass stored significantly more N and P than aboveground stem and leaf biomass. Decomposition rates were low (<10% organic matter loss) and not affected by P enrichment. Nitrogen and P export during winter did not vary across the P enrichment gradient. Export accounted for <10% of observed summer N uptake (1363 mg m⁻²), with denitrification potentially accounting for at least 40% of retained N. In contrast, net P retention was dependent on enrichment; in unenriched mesocosms, P uptake and release were balanced (only 25% net retention), whereas net retention increased from 77% to 88% with increasing P enrichment. Our results indicate that vegetated ditch environments have significant potential to serve as denitrification sinks, while also storing excess P in agricultural watersheds. Full article

(This article belongs to the Special Issue Nitrogen Removal in Agricultural Watersheds: Through Agricultural Practices and Phytodepuration)

► Show Figures

Figure 1

16 pages, 478 KiB

Open AccessFeature PaperCommunication

Combining Tools from Edge-of-Field to In-Stream to Attenuate Reactive Nitrogen along Small Agricultural Waterways

by Brandon C. Goeller, Catherine M. Febria, Lucy A. McKergow, Jon S. Harding, Fleur E. Matheson, Chris C. Tanner and Angus R. McIntosh

Water 2020, 12(2), 383; https://doi.org/10.3390/w12020383 - 31 Jan 2020

Cited by 19 | Viewed by 4018

Abstract

Reducing excessive reactive nitrogen (N) in agricultural waterways is a major challenge for freshwater managers and landowners. Effective solutions require the use of multiple and combined N attenuation tools, targeted along small ditches and streams. We present a visual framework to guide novel applications of ‘tool stacking’ that include edge-of-field and waterway-based options targeting N delivery pathways, timing, and impacts in the receiving environment (i.e., changes in concentration or load). Implementing tools at multiple locations and scales using a ‘toolbox’ approach will better leverage key hydrological and biogeochemical processes for N attenuation (e.g., water retention, infiltration and filtering, contact with organic soils and microbes, and denitrification), in addition to enhancing ecological benefits to waterways. Our framework applies primarily to temperate or warmer climates, since cold temperatures and freeze–thaw-related processes limit biologically mediated N attenuation in cold climates. Moreover, we encourage scientists and managers to codevelop N attenuation toolboxes with farmers, since implementation will require tailored fits to local hydrological, social, and productive landscapes. Generating further knowledge around N attenuation tool stacking in different climates and landscape contexts will advance management actions to attenuate agricultural catchment N. Understanding how different tools can be best combined to target key contaminant transport pathways and create activated zones of attenuation along and within small agricultural waterways will be essential. Full article

(This article belongs to the Special Issue Nitrogen Removal in Agricultural Watersheds: Through Agricultural Practices and Phytodepuration)

► Show Figures

Graphical abstract

17 pages, 1621 KiB

Open AccessArticle

A Mass Balance of Nitrogen in a Large Lowland River (Elbe, Germany)

by Stephanie Ritz and Helmut Fischer

Water 2019, 11(11), 2383; https://doi.org/10.3390/w11112383 - 14 Nov 2019

Cited by 12 | Viewed by 2884

Abstract

Nitrogen (N) delivered by rivers causes severe eutrophication in many coastal waters, and its turnover and retention are therefore of major interest. We set up a mass balance along a 582 km river section of a large, N-rich lowland river to quantify N retention along this river segment and to identify the underlying processes. Our assessments are based on four Lagrangian sampling campaigns performed between 2011 and 2013. Water quality data served as a basis for calculations of N retention, while chlorophyll-a and zooplankton counts were used to quantify the respective primary and secondary transformations of dissolved inorganic N into biomass. The mass balance revealed an average N retention of 17 mg N m⁻² h⁻¹ for both nitrate N (NO₃–N) and total N (TN). Stoichiometric estimates of the assimilative N uptake revealed that, although NO₃–N retention was associated with high phytoplankton assimilation, only a maximum of 53% of NO₃–N retention could be attributed to net algal assimilation. The high TN retention rates in turn were most probably caused by a combination of seston deposition and denitrification. The studied river segment acts as a TN sink by retaining almost 30% of the TN inputs, which shows that large rivers can contribute considerably to N retention during downstream transport. Full article

(This article belongs to the Special Issue Nitrogen Removal in Agricultural Watersheds: Through Agricultural Practices and Phytodepuration)

► Show Figures

Figure 1

23 pages, 6263 KiB

Open AccessArticle

Is Flood Irrigation a Potential Driver of River-Groundwater Interactions and Diffuse Nitrate Pollution in Agricultural Watersheds?

by Erica Racchetti, Francesca Salmaso, Monica Pinardi, Silvia Quadroni, Elisa Soana, Elisa Sacchi, Edoardo Severini, Fulvio Celico, Pierluigi Viaroli and Marco Bartoli

Water 2019, 11(11), 2304; https://doi.org/10.3390/w11112304 - 03 Nov 2019

Cited by 22 | Viewed by 3834

Abstract

In the Po plain, northern Italy, rivers within agricultural basins display steep summer increases in nitrate (NO₃⁻) concentrations. Flood irrigation in overfertilized, permeable soils may drive such diffuse pollution, facilitating interactions between NO₃⁻-rich groundwater and surface waters. We discuss multiple, indirect evidence of this mechanism in the Adda, Oglio, and Mincio rivers. These rivers drain agricultural soils with elevated nitrogen (N) surpluses, averaging 139, 193, and 136 kg ha⁻¹ in the Adda, Oglio, and Mincio watersheds, respectively. The three rivers cross a transitional area between highly permeable and impermeable soils, where summer NO₃⁻ concentrations may increase by one order of magnitude over short distances (8–20 km). Upstream of this transitional area, a major fraction of the river flow is diverted for flood irrigation, a traditional and widespread irrigation technique for permeable soils. We speculate that diverted water solubilizes soil N excess, recharges the aquifer, and transfers soil N surplus into groundwater, resulting in NO₃⁻ pollution. Groundwater–river interactions were estimated experimentally, via water and NO₃⁻ budgets in 0.3 to 1 m³ s⁻¹ km⁻¹ and in 1500 to 5400 kg NO₃⁻–N day⁻¹. The data suggest a pronounced east–west gradient of groundwater to river diffuse water inputs among the three adjacent basins, reflecting the soil permeability and the width of the river–groundwater interaction zone. Given the large stock of NO₃⁻ in groundwater, management interventions performed at the basin scale and aimed at decreasing N excess will not produce an immediate decrease in river NO₃⁻ pollution. Full article

(This article belongs to the Special Issue Nitrogen Removal in Agricultural Watersheds: Through Agricultural Practices and Phytodepuration)

► Show Figures

Figure 1

16 pages, 3947 KiB

Open AccessArticle

Enhancement of Agricultural Policy/Environment eXtender (APEX) Model to Assess Effectiveness of WetlandWater Quality Functions

by Amirreza Sharifi, Sangchul Lee, Gregory W. McCarty, Megan W. Lang, Jaehak Jeong, Ali M. Sadeghi and Martin C. Rabenhorst

Water 2019, 11(3), 606; https://doi.org/10.3390/w11030606 - 23 Mar 2019

Cited by 8 | Viewed by 3578

Abstract

The Agricultural Policy/Environmental eXtender (APEX) model has been widely used to assess changes in agrochemical loadings in response to conservation and management led by US Department of Agriculture (USDA). However, the existing APEX model is limited in quantification of wetland water quality functions. This study improved the current model capacity to represent wetland water quality functions by addition of a new biogeochemical module into the APEX model. The performance of an enhanced APEX model was tested against five observed outgoing water quality variables (e.g., sediment, organic N, NO₃, NH₄ and PO₄) from a wetland within the Eastern Shore of Maryland. Generalized Likelihood Uncertainty Estimation (GLUE) was implemented to assess model uncertainty. The enhanced APEX model demonstrated that it could effectively represent N and P cycling within the study wetland. Although improvement of model performance was limited, the additions of wetland biogeochemical routines to the APEX model improved our understanding of inner mass exchanges within N and P cycling for the study wetland. Overall, the updated APEX model can provide policymakers and managers with improved means for assessment of benefits delivered by wetland conservation. Full article

(This article belongs to the Special Issue Nitrogen Removal in Agricultural Watersheds: Through Agricultural Practices and Phytodepuration)

► Show Figures

Figure 1

18 pages, 3668 KiB

Open AccessArticle

Cover Crops and Landscape Position Effects on Nitrogen Dynamics in Plant-Soil-Water Pools

by Gurbir Singh, Karl Williard, Jon Schoonover, Kelly A. Nelson and Gurpreet Kaur

Water 2019, 11(3), 513; https://doi.org/10.3390/w11030513 - 12 Mar 2019

Cited by 14 | Viewed by 3658

Abstract

Nitrogen dynamics and water quality benefits deriving from the use of cover crops (CCs) are mostly incurred from plot-scale studies without incorporating large-scale variability that is induced by landscape positions. Our understanding of how topography affects the N response in CC systems is limited. The objectives of this study were to evaluate the effects of topography (shoulder, backslope, and footslope) and CCs (cereal rye, Secale cereale L. and hairy vetch, Vicia villosa L.) on nitrogen (N) uptake, soil inorganic N content (nitrate-N, NO₃-N and total N, TN), and N leaching in watersheds that were planted with or without CCs. The crop rotation in CC watersheds was corn (Zea mays L.)-cereal rye-soybean (Glycine max L.)-hairy vetch whereas control watersheds had corn-no CC-soybean-no CC rotation. Data from the watersheds was collected for three cash crop seasons and three CC seasons from 2015 to 2018. Nitrogen uptake of hairy vetch in CC watersheds was 110.9, 85.02, and 44.89 kg ha⁻¹ higher at the shoulder, backslope, and footslope positions, when compared to shoulder, backslope, and footslope positions of no CC watersheds. About 12 to 69% reduction in soil solution NO₃-N and TN was observed with cereal rye CC when compared to no CCs watersheds. However, reductions in soil solution N concentrations were only seen at the footslope position where the hairy vetch reduced NO₃-N and TN concentrations by 7.71 and 8.14 mg L⁻¹ in CC watersheds compared to no CC watersheds. During the corn and soybean growing seasons, similar reductions in soil solution N concentration were only seen at the footslope position in the CC watersheds. The excessive N at footslope positions of CC watersheds may have been fixed in CC biomass, immobilized, or lost through denitrification stimulated by higher water availability at the footslope position. The results of this research can help farmers and stakeholders to make decisions that are site-specific and topographically driven for the management of CCs in row-cropped systems. Full article

(This article belongs to the Special Issue Nitrogen Removal in Agricultural Watersheds: Through Agricultural Practices and Phytodepuration)

► Show Figures

Journal Menu

Journal Browser

Nitrogen Removal in Agricultural Watersheds: Through Agricultural Practices and Phytodepuration

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (10 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI