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'Breaking the pathway’ of P and sediment loss

Wednesday March 24th 2021

The Wednesday discussion is on diffuse phosphorus (P) and sediment losses to waters and how farmers can ‘break the pathway’ of P and sediment losses by putting the right measure in the right locations on farms.

P interactions with soil

Phosphorus is an essential nutrient particularly when it comes to crop establishment. Eddie Burgess, Catchment Specialist with the Teagasc Agricultural Catchments Programme speaks more about managing soil phosphorus for water quality.

Phosphorous is an essential element and is of particular benefit for crop establishment.  Unfortunately phosphorous easily gets fixed to soil and becomes unavailable to growing plants.  The standard soil test measures P that is available, which is usually less than 1% of the total phosphorous in the soil.  Clay content, soil temperature and organic matter all have an impact, but the single biggest thing you can manage to improve P availability is pH.   Spreading lime on acidic soils to bring the soil pH up to 6.3 will make far more phosphorous available than spreading fertiliser.

In grassland, applied phosphorus accumulates in soil close to the surface. When you get a lot of rainfall on heavy soil types, or when the soil is saturated in the first place, most of the water will “run-off” the surface.  Consequently, the water is moving in or on the soil where P is most concentrated.  This “run-off” carries both dissolved P and Phosphorous attached clay particles.  In a typical year 8 or 10 heavy rain storms will carry over half the Phosphorous lost to our rivers and lakes.  Fertiliser, including slurry, spread on wet or frozen soils followed by heavy rain will add to this loss.  Drier soils have the capacity to soak up heavy rain and can reduce phosphorous losses to one quarter the amount.

Eutrophication results from excessive growth of unwanted algae.  In fresh water, a very small amount of phosphorous (under 1 unit per acre) can cause this, leading to reduced oxygen which impacts on life naturally occurring in our rivers and lakes.  Spreading manure at the Right time, in the Right place and at the Right rate will reduce losses, which in addition to saving money, will result in good water quality leaving your farm.

In this clip, Eddie Burgess, Catchment Specialist with the Teagasc Agricultural Catchments Programme speaks more about managing soil phosphorus for water quality.


Water quality and pathway interception

A Riparian Margin is the land that runs alongside our rivers and streams. Here, Fiona Doolan, Teagasc ASSAP Advisor, Co. Laois, talks about a variety of riparian margins. She explains the benefits of a riparian margin on water quality and the role it plays in protecting rivers and streams

What is a Riparian Margin?

A Riparian Margin is the land that runs alongside our rivers and streams. They can vary in width and type but in simple terms they are basically the corridors that are adjacent to our water bodies. The objective of a riparian margin is to protect the river by creating buffer zones alongside them where little or no agricultural activity takes place. Correctly planned and located Riparian margins can be effective in reducing surface water runoff or pollutants from entering waterbodies.

Riparian Margins can range in width from 2m to 30m and sometimes beyond this. Wider riparian margins are beneficial, particularly in more sloped, marginal land where there is a greater risk of overland runoff carrying nutrient and sediment with it.

What do Riparian Margins look like?

In their simplest form they can be an unfenced grass margin – unfertilised and uncultivated yet trapping nutrients from slurry and fertilisers and preventing them making their way into the stream.

Fenced Riparian margins will also prevent access by livestock – reducing damage that could potentially be caused along the banks. Overtime, fenced riparian margins can allow for natural vegetation to become established in the area. The wider the margin, the more protection offered, particularly important in sloped poorer draining land.

Hedgerows and trees in riparian margins can work to improve bank stability – their roots holding the bank together preventing erosion. In some cases Riparian margins can be wider larger areas, devoted to woodland / scrub or natural habitat– encouraging nature as well as protecting Water Quality. Riparian margins such as these provide other environmental benefits including increased biodiversity and carbon sequestration.

Riparian Margins can be in many different forms yet despite the differences in what they contain, all riparian margins have the potential to protect the rivers and streams they are adjacent to and enhancing the wider environment around them.

In this short video Clip Fiona Doolan, ASSAP Advisor shows us a few good examples of Riparian Margins. 

Farm Roads 

Farm roadways are an essential piece of infrastructure on most livestock farms and in particular dairy farms. Under new Nitrates rules there shall be no direct runoff of soiled water from farm roadways to waters from 1st January 2021. Padraig Fitzgerald, Teagasc Advisor lists the key points involved

New Nitrates Rules from 1st January 2021

Roadways help farmers in achieving high animal performance from pasture based systems by aiding grassland management. Under new Nitrates rules that have come into effect there shall be no direct runoff of soiled water from farm roadways to waters from 1st January 2021.

The aim of the measure is to prevent runoff of sediment and nutrients from farm roadways thereby protecting and improving the water quality. Excess sediment getting into a watercourse can impact on the habitat of the river bed. It can also bring with it excess nutrients such as phosphorous which impacts on the water quality.

Research on dairy farms in Ireland has shown that a dairy cow can deposit up to 8 litres of urine and manure on farm roadways each day. As a result, significant amounts of sediment, animal manures and urine are frequently observed to accumulate on the surfaces of these roadways. Because farm road surfaces tend to be mostly hard and compacted, much of this material simply sits on the road surface where it can be washed off the road following rainfall events. Very often a high rainfall storm event can result in significant levels of sediment and nutrients moving very quickly off farm roads and into rivers and drains.

These new rules apply to all farmers who have farm roadways beside watercourses, rivers, drains or any feature that can carry water.

Some key points to remember when constructing roadways:

  • Camber the roadway away from the stream or drain using a cross fall of 1to 25. Thus diverting the run off towards a field or a paddock.
  • All new roads installed on farms beside watercourses or drains must be 1.5m back from the top of the bank from watercourse or drain.
  • Existing farm roadways running beside a watercourse that are already fenced do not require the 1.5m buffer margin. A good camber away from the watercourse is still required.
  • Moving paddock access >5m from watercourse/drain is also recommended to reduce the possibility of any sediment/nutrient entering watercourse/drain.

Source: Department of Agriculture, Food & the Marine (DAFM) Specification on Farm Roadways S199 on www.gov.ie/agriculture 

Runoff issues from farm roadways are extremely variable from farm to farm. Each farm is different and one needs to look at things like soil type, stream and drain density on the farm, slopes, roadway condition and herd size when one is to consider a solution to preventing the runoff from farm roads to watercourses or drains.

In this clip, Padraig Fitzgerald, Teagasc Advisor goes through some key points to remember when constructing roadways on the farm.


P use on organic soils 

A recent analysis conducted by the Teagasc Rural Economy and Development programme indicates that approximately 6% of the country (420,000 Ha) is made up of cultivated peats across a wide range of farming intensities. Fiona Doolan, ASSAP Advisor Kildare/Laois, discusses Phosphorus Use on Peat Soils

A recent analysis conducted by the Teagasc Rural Economy and Development programme indicates that approximately 6% of the country (or 420,000 Ha) is made up of cultivated peats across a wide range of farming intensities (though predominately low intensity farming). There are however some intrinsic differences between peat soils and mineral soils in relation to nutrients, particularly Phosphorous (P), and how the soil stores and uses them.

Phosphorous is a nutrient that can have negative effects on water quality if it is lost to streams and rivers. It is vital that we manage P applications carefully to improve efficiency, get the best financial return for the farmer and also reduce the risk of loss to our waters.

It is important to note that peat soils behave differently to mineral soils, when it comes to some nutrients such as phosphorous.  High organic matter soils (OM > 20%) do not adsorb P in the same way that mineral soils do. Therefore P does not bind to peat soil particles so do not have the capacity to build up or increase the store of phosphorous they hold. Applications of fertiliser P on peat soils may be lost (leached) to water if P is not utilised by the growing plant during periods of rainfall. 

So what is the best approach to take to ensure fertiliser P applications get utilised by the grass or crop?

1. Only apply the phosphorus that the plant needs and can use for growth – do not apply excess amounts of P; peat soils cannot build up its phosphorous levels so it will be an expensive exercise to apply more than the crop needs with no long term advantage to the soil. This applies whether its phosphorous applied in chemical form or organic fertiliser.

2. Timing of application. Match application to the growth period of the crop and crop requirement. Do not apply earlier, in advance of the crop requirement as this may be lost to waters and do not apply late in the season as growth rates will have slowed down. In grassland peat soils, a little and often approach is recommended to ensure applied P is taken up by the grass crop and not lost to waters.

In summary:

  • P  Peat soils behave differently to mineral soils and are not capable of holding or building up phosphorous
  • E  Evenly match application to what the growing crop can use and do not target a build-up application
  • A  Apply this during the growing season so match the crop demand
  • T  Take account of your NMP plan and adhere to buffer margins when spreading.

In this clip Fiona Doolan, Teagasc ASSAP advisor advises on applying phosphorus fertilisers to peat soils. 


Land drainage & water quality

Ireland lies in a temperate zone where the main role of drainage is the removal of excess water in the root zone of crops from surplus rainfall, improving land trafficability and increasing productivity. Meabh O'Hagan, ASSAP Advisor and Niall McLoughlin, Lakeland Dairies has some advice.

When soils are saturated or waterlogged, water will flow over the surface moving sediment and nutrients into our waterbodies. This is known as Overland Flow. The function of a main drainage system is to collect, transport and dispose of water collected from the field drainage system through an outlet.  Main drains may also collect excess water directly from the fields themselves (surface and groundwater).

Appropriately designed and constructed land drainage will lead to improved nutrient uptake by the plant. This can lower losses of nutrient and sediment to watercourses, however great care must be taken to ensure that drainage channels do not become pathways for losses of nutrients. 

Water quality in Ireland has been falling over the last number of years. Hydromorphology which includes land drainage and channel straightening is the second biggest pressure on water quality in Ireland. 

To minimise sediment and nutrient losses when carrying out drain maintenance, adhere to the following practices:

  • Any maintenance to surface water drains should only be carried out during the months July to September. Fish and their spawning grounds are protected under the Fisheries Acts (1959 – 2010). In-stream works should not be carried out without prior consultation and approval of Inland Fisheries Ireland (www.fisheriesireland)
  • When cleaning drains it is recommended that only one side of a drain is cleaned at a time leaving the opposite bank undisturbed. Do not clean the opposite side until sufficient growth has regenerated on the first to ensure the bank has stabilised. 
  • Drains should not be over-cleaned, retain as much vegetation as possible only removing material from the bottom of the drain. Only clean the lengths where flow is impeded leaving the stone and gravel in-situ. 
  • Ensure the bank is sloped afterwards to prevent collapse. Unstable banks can increase sediment and nutrient loss to the watercourse. The following table outlines recommended bank slopes.

  • In order to avoid sediments entering a waterbody a 20m length of uncleaned drain should be kept at the lowest length of the drain to act as a sediment trap.
  • Spread the spoil as soon as possible after cleaning, ensuring adequate distance between the spreading area and the open drain and spread it as thinly as possible.
  • In the course of carrying out maintenance leave as much vegetation as possible in place along the banks and margins. Native hedgerows along watercourses can stabilise the bank and act as a natural buffer zone while providing an important habitat.
  • Fence off the drain afterwards leaving a minimum of 1.5m fenced buffer. Allowing vegetation to develop along this riparian margin can help trap nutrients and sediment preventing them from entering drains.
  • There is a requirement for a 5m buffer when spreading organic manures along all surface water drains and this expands to 10m for the two weeks either side of the closed period. This will help prevent drains from becoming a pathway for nutrients to enter rivers and streams.

Due consideration should be given to impacts on wildlife, water and biodiversity prior to undertaking any new drainage works. Wetlands have the highest biodiversity value of any farm habitats. Fish bearing or spawning streams should never be cleaned – refer to Inland Fisheries Ireland if you have any concerns about waterbodies in your locality.

Speak to your agricultural advisor before carrying out any maintenance on surface water drains to ensure you are not impacting water quality.

In the below video, Meabh O'Hagan, ASSAP Advisor and Niall McLoughlin, Lakeland Dairies go through some steps you can take to minimise sediment and nutrient losses when carrying out drain maintenance.


The Caha Project (incl. farmer testimonial)

The Caha Project is a project where nine farmers have come together to protect a section of their local river. This length of river is particularity important as it has been identified as having a High Status Objective and is a Priority Area for Action under the Water Frameworks Directive

The southern section of this project takes place along a length of the river which is SAC (Special Area of Conservation) due to the presence of endangered species such as the Freshwater Pearl Muscle. This length of river also is of historical significance being the location where seventeen people were murdered in 1793, along with many other interesting and historically important events. It is an important salmonid spawning section of the Bandon River Catchment and is a fantastic amenity to the local community.

The Caha Project participants have received a Community Waters Grant to help to fund the fencing off of approximately 3300m of the river and provide an alternative water source to the adjacent fields. This action will prevent cattle from directly damaging the river bed and protect species like the Freshwater Pearl Muscle, it will help to prevent sediment from entering the waterway and it will enhance biodiversity along the river bank. All of this will help to protect and improve the water quality of the river and preserve the natural heritage of the Caha River.

Lane Giles, Teagasc ASSAP Advisor and Ciara Donovan, Dairygold have more information in the below video.

Smarter BufferZ

Riparian buffer zones are patches of land adjacent to rivers, streams and drains, removed from intensive production. When designed correctly, they play a significant role in the reduction of diffuse inputs from agriculture entering our waterbodies.

Buffer zones provide a variety of environmental and ecological services, including:

  • a habitat for biodiversity
  • alleviating flood threat
  • greenhouse gas exchanges
  • recreational services. 

The SMARTER_BufferZ (Specific Management And Robust Targeting of Riperian Buffer Zones) project aims to ensure optimal targeting and management of riparian buffers for the effective management of Irish rivers.

Narrow grass buffers are often insufficient to intercept diffuse inputs such as Phosphorus along with sediment being lost from fields through overland flow. A wider buffer area is often required along with rough dense vegetation or raised ground in a targeted approach. Well designed and managed riparian buffers will slow flows and trap nutrients and sediment. The introduction of trees in these areas can act as a barrier to spray drift, shade streams and stabilise river banks while the roots can absorb soil nutrients.

When installing riparian buffers on farms a chain of treatment or mitigation action works best. This can include good soil and field management along with well-designed and maintained targeted riparian buffers.

Get more information on SMARTER_BufferZ here

Buffer Zones for Fertiliser Applications

Once the growing season arrives farmers begin to apply nutrients to their lands. This can be in the form of chemical fertilisers or organic fertilisers. Organic fertiliser includes soiled water, effluents, farmyard manure, slurry etc. As well as abiding by the regulations governing good practice when deciding to apply these fertilisers the farmer must also know the relevant Buffer Zones. A Buffer Zone is a no spread area which is used for the protection of water against pollution.

The loss of nutrients to our waters is causing a decline in water quality. As a country we are required to have all our waters achieving “good status” by 2021 which is a goal we must all work towards. Nitrogen and Phosphorous loss from agriculture are the main nutrients which are prone to loss and contributing to the decline in this regard.

Nutrient enrichment occurs when excess nutrients are not retained on land or used by the growing crop and subsequently are lost to water. Phosphorous is most prone to loss from low permeability soils or soils which are peaty in nature. This loss occurs through overland flow of water which carries sediment and P into drains and surface waters. Conversely most Nitrogen losses occur from free draining and light soils as N does not bind tightly to soil. The application of more N than the growing plant can take up leads to loss through leaching downwards through the soil to waters.

In all cases to mitigate against the loss of N and P to waters we can “Break the Pathway” through the use of buffer zones. A buffer zone may be fenced or unfenced, planted with trees or just grass, but in all cases acts to intercept and take up excess nutrients before they negatively impact on water. Buffer zones are no spread zones for nutrients. Ditches and drains are designed to remove water from fields but act as corridors and connecting pathways for nutrients and so buffer zones should be sited along these areas of potential loss.

In order to prevent waters from being polluted by nitrogen and phosphorus, the European Union (Good Agricultural Practice for Protection of Waters) Regulations, 2014 require that you must adhere to the following buffer zones. 

You Must Not Spread

  • Chemical fertiliser on land within 2m of surface waters

You Must Not Spread Organic Manure Within

  • 5m of surface waters (extends to 10m for first 2 and last 2 weeks of open season)
  • 10m of surface waters where the slope towards water exceeds 10%
  • 15m of exposed cavernous or karst features such as swallow holes
  • 20m of Lake Shoreline           
  • 25-200m of water abstraction point for human consumption

Exclusion of Bovines from Watercourses and Location of Water Troughs

Under the Nitrates Action Plan a number of measures have come into being since 1st January 2021 aimed at further enhancing the protection of water. The headline measure is the requirement to prevent the runoff of sediment and nutrients from farm roadway to any kind of structure that can convey water ( lakes, rivers, streams, watercourses even dry drains ). There are two other very important measures worth noting. The first one is the “exclusion of bovines from watercourses” and the second one is the “location of water troughs away from watercourses”.

So who do these two water protection measures apply to?

They apply to farmers that have a grassland stocking rate over 170 kg. N. / Ha. in the previous year, which is 2020.

  • They apply to farmers who exported organic manure to come back under the 170 kg N. / Ha. in 2020
  • They apply to Tillage farmers with grassland, where that Grassland is stocked at greater than 170 kg N. / Ha. in 2020
  • And of course they applies to all Derogation farmers.

What type of water conveying system do these measures apply to?

They apply to Watercourses that are marked on a 1:5000 scale Ordnance Survey map. These maps can be looked up on the Ordnance Survey Ireland ( OSI ) website. The watercourses will appear as a continuous blue line ( not broken or mottled ). They can be of varying thickness reflecting the size of the watercourse. See link to accessing these maps. If in doubt about whether the watercourse is marked on the OSI map it is best to fence it.    Here is the link OSI Place Map

Instructions: Choose -  Customise -  Paper options choose A3 – Scale choose 1:5000 – Zoom in to bring up your farm and note the watercourses.   Contact your Agricultural advisor if you are having difficulty getting the maps on the OSI website. 

1. Exclusion of Bovines from watercourses

The idea of this measure is to prevent the degradation of water course banks and damage to the watercourse bed and hence avoid the transfer of soil and nutrients to water.

The requirement is to erect a bovine proof fence 1.5 meters out from the top of the watercourse bank. If there is a an existing fence in place that is closer to the watercourse bank than the 1.5 meters this will either have to be moved out of another fence placed outside it that is at least the 1.5 meters out from the watercourse bank. This fence could be of a temporary nature ( pigtail stakes and flexible wire ). No bovine access is allowed for drinking. If bovines have to walk through a watercourse for access to a land parcel the crossing must be fenced both sides so that the bovines can’t walk up or down the watercourse.

2. Water trough location

This measure is aimed at preventing the likelihood of sediment and nutrients created around drinking troughs from finding their way to the adjacent water.

Water troughs cannot be located closer than 20 meters from a watercourse. In very narrow paddocks that have watercourses on all sides the trough must be located the maximum distance possible from the watercourses, this may be less than 20 meters.

The above two measures along with others will help to protect water quality and the biodiversity and wildlife these habitats support. They will also help Irelands case for the retention of the Nitrates Derogation and uphold our national environmental law.

Loch an Chuais, Uíbh Ráthach

Labhair Daire Ó hUallacháin (Teagasc) le Helen Ní Shé (ó Raidio na Gaeltachta) faoi taobh de stádas uisce na tíre. Rinne sé cuir síos ar chonas mar a mheastar stádas uisce agus cad h-iad na baoil eagsúla atá ann (msh, talamhaíocht, faraoiseanna, títhíocht). Phléigh siad stádas aibhneacha Choirce Dhuibhne agus Uíbh Ráthach. Chríochnaigh siad le cuir síos ar na h-iarrachtaí atá ASSAP, Teagasc, LAWPRO, na comhar-chumainn, EPA agus grupaí eile ag déanamh chun chaighdeán uisce na tíre a chaomhnú.

Daire Ó hUallacháin (Teagasc) spoke with Helen Ní Shé (from Radio na Gaeltachta) about the status of water in the country. He described how the status of water is assessed and what the various risks are (eg, agriculture, forests, housing). They discussed the status of rivers on the Dingle and Iveragh peninsulas. They concluded by describing the efforts being made by ASSAP, Teagasc, LAWPRO, the co-ops, EPA and other groups to conserve the country's water quality.

What impact can weed control & drainage work have on water quality? 

The Beef Edge Podcast

Agricultural Sustainability Support and Advice Programme advisors Mary Roache & Meabh O’Hagan join Catherine Egan on this week’s Beef Edge podcast as part of Water Quality Week to highlight correct weed control management & tips on carrying out drainage work to reduce impact on water quality.

Firstly, Mary discussed the main types of weeds farmers want to control.  With docks being the most common, Mary discussed the chemical and non-chemical methods of control.  Mary also advised farmers as to what they must look out for when using pesticides to avoid getting any into our water supplies such as correct application rate, method and buffer zones.

To conclude Mary advised farmers to look at the Basic Payment pack they received recently to complete the necessary recording paperwork for cross compliance. Only a DAFM-registered professional user can apply Plant Protection Products that are authorised for professional use.  It is a requirement for sprayers over 3 years of age to have passed a Pesticide Application Equipment Test before being used to apply professional use Plant Protection Products. 

Meabh then discussed how land drainage impacts water quality and how farmers can minimise the impact. When it comes to carrying out new drainage works, Meabh advised to consider the bigger picture in relation to new environmental schemes in the future and to talk to your advisor in advance of undertaking any work.

Meabh highlighted that drain maintenance should only take place when needed and after spawning has occurred from July- Sept.  She also advised on the ways to minimise the amount of maintenance drains require.

Farmers can get more information about how to appropriately carry out drainage and drain maintenance here: https://www.teagasc.ie/environment/soil/soil-drainage/

Find further information here on Water Quality Week

For more episodes and information covered on the Beef Edge, visit the show page at: www.teagasc.ie/thebeefedge