Farm management sq

In this section of FAIRWAYiS we review and assess measures and practices aimed at maintaining and/or improving water quality of drinking water supplies.

We

  • review and assess measures and practices aimed at decreasing nitrate pollution of drinking water supplies;
  • review and assess measures and practices aimed at decreasing pesticides pollution of drinking water supplies;
  • identify and assess most promising measures and practices to decrease nitrate and pesticide pollution of drinking water supplies.

Subcategories

Main authors: Oene Oenema, Meindert Commelin, Piet Groenendijk, John Williams, Susanne Klages, Isobel Wright, Morten Graversgaard, Irina Calciu, António Ferreira, Tommy Dalgaard, Nicolas Surdyk, Marina Pintar, Christophoros Christophoridis, Peter Schipper, Donnacha Doody
FAIRWAYiS Editor: Jane Brandt
Source document: »Oenema, O. et al. 2018. Review of measures to decrease nitrate pollution of drinking water sources. FAIRWAY Project Deliverable 4.1, 125 pp

 

Sufficient safe drinking water is vital for human health, public welfare and an important driver of a healthy economy. This drinking water is extracted from groundwater (aquifers) or surface waters, and in many countries purified before consumption. About 2 billion people in the world lack sufficient safe drinking water, mostly in Africa and Asia. In the European Union about 65 million people are exposed to drinking water resources which quality cannot be guaranteed. Further, many drinking water resources run the risks of pollution by nitrates and pesticides, resulting from the intensification of agricultural production. In response, drinking water authorities have taken a range of measures around their drinking water resources to reduce the pressures from pollution, and have invested in various purification steps, or in the closure of wells when contamination was unacceptably high. In addition, various policy measures have been implemented as a blanket in the European Union from the early 1990s onwards to decrease the pollution of drinking water resources with nitrates and pesticides. The current view is that not all measures are equally effective, and that the protection of drinking water resources has to be improved.

In this section of FAIRWAYiS we review and assess measures to decrease nitrate pollution of drinking water resources. The work builds on insights and results gathered in EU-wide and global projects and studies. It provides an overview and assessment of the effectiveness and efficiency of measures aimed at decreasing nitrate pollution of drinking water reservoirs.

»Background and objectives of the review shows that various reviews on measures aimed at decreasing nitrate leaching have been published already, but either these reviews focussed on single measures or were rather qualitative and descriptive in nature. The novel aspect of this review is that the accessible literature has been screened for experimental data related to the effectiveness of most measures to reduce nitrate pollution of groundwater and surface waters, in a coherent and quantitative manner, using statistical analyses.

»Review methodology describes the two surveys that were conducted.

  • Firstly, a survey of practical guidelines and measures, also at the case study sites, and earlier inventory reports yield gross lists of some 40 measures. All these measures were uniformly and concisely described and are to be found in Annexes 1 and 2 of »Review of measures to decrease nitrate pollution of drinking water resources.
  • Secondly, a survey of published literature was conducted to identify papers that reported experimental results on the effectiveness of measures to decrease nitrate leaching, using the ISI-Web of Science and Google Scholar from 1980 to 2017. The reviews were conducted by different review teams covering different geographical regions using an approved protocol. Results were stored in a database and analysed statistically.

»The nitrogen cycle and nitrogen transformation processes provides background information about the sources of nitrate nitrogen in agriculture and about the processes and factors that contribute to the pollution of groundwater and surface waters with nitrates. The nitrogen cycle has been characterised as leaky and complex. Main sources are animal manures and synthetic fertilizers, but also residues and wastes, and the mineralization of soil organic matter following land use change can be sources regionally. Estimates suggest that some 60% of the amounts of nitrogen entering the aquatic system originates from diffuse agricultural sources in EU-28, which is about 6 Tg (1 Tg is 1 million ton is 1012 g), and equivalent to 60% of the N fertilizer use in EU-28.

»Agriculture in EU-28 and the use of nitrogen presents background information about agricultural systems and land use in EU-28 and about management factors that influence nitrogen use in agriculture. The nitrogen input-output balance is a synthetic manner for summarizing N use at farm level but also at regional and national levels. We also discuss the difficulties of optimizing N fertilization due to site and temporal variations in N demands by growing crops.

»Processes and factors that transfer nitrates to drinking water resources describes the hydrological cycle and pathways of N transfers from land to groundwater and surface waters. The potential risks of runoff and leaching of nitrate and nitrogen to surface waters is determined by a combination of pedo-climatic factors and the amounts of nitrate and nitrogen in the top soil. Important pedo-climatic factors are:

  1. rainfall amount and distribution, especially heavy rainfall events, and
  2. water infiltration rate into the soil.

The latter is determined by slope, soil texture, soil structure, soil depth to underlying rock, vegetation cover, snow and frost and freeze-thaw cycles, and the presence of terraces, tree-lines, buffer zones, riparian zones, which all contribute to intercepting overland flows. Soils with a high nitrate leaching vulnerability have a high infiltration rate and a high hydrological conductivity, such as coarse-sandy soils and shallow soils overlying karst formations.

»Overview of measures and practices that decrease nitrate losses describes how the mean cost-effectiveness of most measures aimed at decreasing nitrate losses from agriculture to ground and surface waters roughly ranged from 1 to 5 euro per kg N, but the uncertainty in the cost-effectiveness is large, and some measure had higher costs. At farm level, the cost of the measures ranged from a net gain to a cost of more than a few thousands euro per year.

»Further characterisation of key measures that decrease nitrate losses examines in further detail the rational and effectiveness of 11 key measures and serves as basis for a further quantitative analysis in the next article.

In »Quantitative analysis of measures and practices a total of 84 papers with 228 experimental comparisons are examined and utilized for statistical analyses; these papers report experimental data related to measures aimed at decreasing nitrate leaching losses. Most measures were on effective overall, but some not as effective as others. Effective measures were

  1. N input control,
  2. adjustment of crop type and/or crop rotation,
  3. growth of cover crops,
  4. minimum tillage and surface mulching, and
  5. nitrification inhibitors.

Somewhat surprisingly, fertilizer type and time and method of application turned out to be not effective. These initial results need further underpinning. Moreover, the effective measures do show a wide variation; the 95% confidence interval of the mean response ratio was often very large, which is probably related to site-specific variations in socio-economic and environmental conditions.

»Implication of review findings discusses the importance decreasing nitrate pollution and considers the effectiveness, cost-effectiveness and applicability and adoptability of different measures. Our findings largely confirm the observations of earlier reports, but some meta-analysis studies provide additional and different results.

In summary, the variability in the effectiveness of measures to decrease nitrate leaching losses across sites is possibly one of the reasons for the widespread recording of nitrate concentrations exceeding 50 mg/L in groundwater and surface water monitoring stations, despite the implementation of series of measures during the last 2 to 3 decades. It shows a need for farm-specific packages of measures. This review and the subsequent »Report on most promising measures are important scientific building blocks for the further development of innovative measures and governance approaches for a more effective drinking water protection, together with local, regional and national actors.  

 


Related articles

Main authors: Meindert Commelin, Jantiene Baartman, Piet Groenendijk, Oene Oenema, Susanne Klages, Isobel Wright, Tommy Dalgaard, Morten Graversgaard, Jenny Rowbottom, Irina Calciu, Sonja Schimmelpfennig, Nicola Surdyk, Antonio Ferreira, Violette Geissen
FAIRWAYiS Editor: Jane Brandt
Source document: »Commelin, M. et al. 2018. Review of measures to decrease pesticide pollution of drinking water sources. FAIRWAY Project Deliverable 4.2, 79 pp

 

In this section of FAIRWAYiS we review and assess measures to decrease pesticide pollution of drinking water resources. The work builds on insights and results gathered in EU-wide and global projects and studies. It provides an overview and assessment of the effectiveness and efficiency of measures aimed at decreasing pesticide pollution of drinking water reservoirs and complements the section »Review of measures to decrease nitrate pollution of drinking water sources.

We start by giving some background information on changes in the use of pesticides, concerns about their safety, EU directives and guidelines, factors that affect their pollution potential and measures that are used to reduce and control it.
»Background.

Pesticides are used at different rates in Europe and around the world; as a general rule more intensive agriculture will also use more pesticide per ha. In the EU the average use is around 3.0 kg/ha per year. Groundwater and rivers are monitored in the EU to control the water quality and pesticide levels are also checked. We give an overview of farming systems and management in the EU-28, use of pesticides and monitoring of residues in drinking water before taking a quick look at pesticide use in the rest of the world.
»Agriculture and pesticides use in the EU-28 and worldwide

We then look at the existing pathways and transport mechanism of pesticides to water resources. The driving factors for pesticide pollution are in firstly water facilitated transport through or over the soil. Secondly erosion of sediment can transport sorbed particles. Areal transport occurs with spray drift during application and is a threat to surface water quality.
»Processes and factors that transfer pesticides to drinking water resurces

To conduct the review of measures to decrease pesticide pollution we undertook a systematic search through online databases and via local searches by partners of the FAIRWAY project throughout Europe. The search yielded 112 experimental comparisons in both journal articles and reports of institutes and universities. In addition a survey was done among the partners and case studies to investigate existing measures and their performance. All these measures were uniformly and concisely described.
»Review methodology

The review is in two parts. Firstly there is a qualitative review of described and tested agricultural measures in scientific literature and in the case studies
»Qualitative review of measures and practices that decrease pesticide pollution.

This is followed by a quantitative analysis of the effectiveness of these measures to reduce pollution of ground and surface water.
»Quantitative analysis of measures and practices.

We finish with the main findings of this review which are:

  • Measures can be categorized into either source-based or pathway-based measures. Each pathway (leaching to ground water, or overland transport to surface water) has its own specific and effective measures. Spray drift forms a separate pathway to surface water.
  • The driving factors for pesticide pollution are in the first place water facilitated transport through or over the soil. Secondly also erosion of sediment can cause transport, when sorbed particles are transported. Areal transport occurs with spray drift during application, and is a threat for surface water quality.
  • Buffers, drift reduction measures and IPM are effective measures to reduce pollution.
  • Tillage methods are extensively studied in relation to pesticide pollution, but they do not have a clear effect and are thus not effective to be used to reduce pollution of either ground or surface water
  • For all measures, the local design and pedo-climatic conditions are of major importance to be effective. A quantified relation between pedo-climatic conditions and measure design or effectiveness is still lacking and would improve the applicability of these measures.

»Discussion and conclusions

 


Related articles

Main authors: Mart Ros, Gerard Velthof, Oene Oenema, Meindert Commelin, Susanne Klages, Linda Tendler, Jenny Rowbottom, Isobel Wright, Donnacha Doody, Luke Farrow, Birgitte Hansen, Morten Graversgaard, Irene Asta, Andrej Jamsek, Katarina Kresnik, Matjaz Glavan, Jean-François Vernoux, Nicolas Surdyk, Christophoros Christophoridis, Kate Smith, Irina Calciu, Sonja Schimmelpfennig, Hyojin Kim, Piet Groenendijk.
FAIRWAYiS Editor: Jane Brandt
Source document: »Ros, M. et al. 2020. Identification of most promising measures and practices: 2. Reduction nitrate transport from agricultural land to groundwater and surface waters by management practices. FAIRWAY Project Deliverable 4.3, 72 pp

 

For a description of the background issues concerning the agricultural use of nitrates and their contamination of drinking water supplies see
»Background and objectives of the review

In this section of FAIRWAYiS we review the effectiveness of management practices for reducing NO3 losses to ground and surface water resources. We combine

  1. a synthesis of existing review papers,
  2. a meta-analysis of available data from literature and
  3. practice based knowledge from nine case studies across Europe.

»Materials and methods
»Results and discussion

Our main conclusions are:

  • A review of existing meta-analyses and quantitative reviews showed that there is a lot of information available on the effectiveness of measures to reduce NO3 losses to ground and surface waters. In particular the use of cover crops, (nitrification) inhibitors, and biochar has been well documented, often in relationship with other N parameters, such as N2O emissions or soil N transformations.
  • The use of non-legume cover crops appears an effective way to reduce NO3 losses. This effect is often diminished when legumes are included. Application of DCD also seems to be effective as a measure and cost-benefit analyses show that this can be profitable. For other measures, such as biochar and changes in tillage practices, the results differ.
  • The success of the implementation of a measure often varies per farm and per location. It is subject to differences in topography, climate, and other farm management practices. Farm-tailored solutions are therefore likely to yield result. This is illustrated by the large variety of measures proposed by the case study experts and the differences in applicability.
  • Implementation of measures to reduce NO3 losses should not only consider the effectiveness, and costs, but also the adoptability and possible (unwanted) side-effects. While some measures may for example decrease NO3 and N2O losses, they could increase NH3 volatilization. These effects of the measures on the N cycle and possibly those of other nutrients should be considered. This is true for measures at both the field and farm scales.

 


Related articles

Main authors: Meindert Commelin, Shaun Coutts, Jantiene Baartman, Isobel Wright, Antonio Ferreira, Gerard Velthof, Oene Oenema and Violette Geissen
FAIRWAYiS Editor: Jane Brandt
Source document: »Commelin, M. et al. 2020. Identification of most promising measures and practices: 1. Reduction of diffuse pesticide transport from agricultural land to groundwater and surface waters bymanagement practices. FAIRWAY Project Deliverable 4.3, 72 pp

 

For a description of the background issues concerning the agricultural use of pesticides and their contamination of drinking water supplies see
»Background

In this section of FAIRWAYiS we investigate the effectiveness of on-field management practices (including soil tillage practices, vegetative filter strips, application management and drift reduction) for reducing diffuse pesticide pollution by transport to ground and surface water resources.

We combine

  1. a synthesis of existing review papers,
  2. a meta-analysis of available data from literature and
  3. practice based knowledge from nine case studies across Europe.

»Materials and methods
»Results

Our main conclusions are:

  • The driving factors for diffuse pesticide pollution are (i) the amount and type of used pesticides, (ii) water facilitated transport through or over the soil, (iii) erosion of sediment that causes transport of sorbed particles, and (iv) spray drift during application.
  • Vegetated filter strips are the most clear measure to reduce overland transport and pollution by pesticides. Models are available to calculate dimensions and predict effectiveness for pesticide reduction.
  • Tillage practices are extensively studied in relation to off-site transport of pesticides. The analysis shows that no-till does not provide less off-site transport than conventional tillage, and suggests even higher pollution in no-till systems under specific circumstances.
  • On-site measures against diffuse pollution comprise only a small part of the available ap-proaches to reduce pesticide pollution. To obtain a sustainable system, input reduction, farm system redesign, point source mitigation and policy measures are essential to be taken into account.

»Discussion and conclusions

 


Related articles

Go To Top