Perhaps one of the most important statements made at last week’s ITLUS conference is that manure application matters to field performance. Also, organic manures are best recycled on the land in a controlled manner taking account of the risks to water, odour, noise and disease.

Last week’s ITLUS (Irish Tillage and Land Use Society) meeting focused on the use of manures in tillage to help improve both the fertility and the biological and physical characteristics of worn land. It also looked at the influence and impact of environmental legislation and the need for safe and sustainable use of these products. This article focuses on these issues.

At the conference, Seamus Barron from the nitrates division of the Department of Agriculture Food and the Marine outlined the requirements of legislation with regard to water quality, the nitrates action plan and organic manures. He referred to the recent EPA water quality report which indicated a 3% deterioration in water quality in 2017.

The main nutrients involved are nitrate and phosphate, which give rise to eutrophication, and the report stated that 44% of monitored river water bodies had less than good ecological status. While 197 of the monitored rivers showed improved ecological status, some 269 of them showed reduced status compared with the last assessment.

Areas that are posing particular concerns have been found and these relate to factors relating to soil type, geology and rainfall level. He went on to say that the ‘Agricultural Sustainability Support and Advisory Programme’ is now focussing on 190 priority ‘Areas-for-Action’. This programme will operate from 2018 to 2021 and will focus on 729 out of a total of 4,832 water bodies all around the country.

Soil fertility

While excess nutrients are a cause for concern in water, it is likely that inadequate fertility in soils may be contributing somewhat to that problem. Low soil pH adversely affects many different soil functions and even though there is a slight improvement in pH values, almost two-thirds of soils are below 6.2 pH. And on phosphorous, Seamus commented that, while high-risk Index 4 levels are decreasing, this is largely happening through an increase in poor fertility Index 1 levels.

While Index 4 soils do present an increased risk of nutrient loss, especially of phosphorous, good balanced fertility in conjunction with improved biological activity can help to reduce nutrient loss. Anything which increases the ability of water to percolate will tend to reduce surface flow and loss while improved soil structure will foster higher yield potential.

So improving soil fertility, especially soil pH, can be seen as a way of reducing nutrient loss to the environment. Crops that are growing actively consume more of the available nutrients in a soil and thus decrease the risk of loss. One of the modern approaches being considered to help prevent loss to water focuses on measures that break the loss pathway. In this regard taking specific measures at any point where nutrients could be lost would be seen as a benefit.

For soil analysis and fertility assessment to be useful at farm level it should be conducted in a judicious manner. Soil analysis and testing must be seen as a tool to improve efficiency rather than a box ticking exercise. But now that environmental protection is also part of the requirement for soil testing, the Department has introduced a reduced sample area and increased frequency to try to improve accuracy.

Up until recently, a farm had to produce a soil sample for every eight hectares farmed and this had to be repeated every five years. Now a sample must be done for every five hectares farmed and a sample is only valid for four years. This is targeted at more accurate soil analysis and planning. Indeed, one might add to this the need for farmers to be guided on the location and number of soil samples by observing variations in crop growth and performance.

Speakers at the ITLUS conference included Patrick Forrestal of Teagasc, Johnstown Castle, Duncan Rose of NRM UK, Brendan Cooney, Wexford County Council, Seamus Barron of DAFM and Ivan Whitten, Teagasc Naas.

New measures

It is also interesting to note another new guidance measure which specifies that where soil organic matter level is 20% or higher, one is not allowed to apply rates of P fertiliser that are above maintenance levels, ie no soil-building allowance. This is targeted at minimising the risk of loss from peaty soils which are very poor at holding P.

Seamus also outlined new soil fertility ‘build-up’ arrangements of Index 1 & 2 grassland soils. This applies to farms with a stocking density equivalent to greater than 130kg P/ha/year. These allow an additional 30kg P/ha to be applied to Index 1 and an additional 20kg P/ha to be applied to Index 2 soils subject to certain provisions such as soil analysis, a nutrient management plan, being in a KT group and partaking in a four-year programme.

However, no such equivalent measure is available to tillage farmers in similar low fertility situations and Seamus indicated that this was because it was not sought by Teagasc. However, it must be noted that tillage farmers are allowed to apply up to 20kg P/ha up to 31 October when planting winter cereals, ie apply this amount of P between 15 September and 31 October. The difference is that this quantity must be part of the total allowance.

Use of manures

A number of presentations on the day outlined the huge variability in the nutrient and carbon content of different organic manures. Much of the difference relates to how the products were manged prior to testing but they do outline to farmers the massive variability that can exist. However, knowing this is of little benefit to farmers as test results cannot be used to fulfil nutrient management plans.

Seamus was very adamant that this is the case and that book values will be used by the Department when assessing nutrient use plans, even where the test result might have been only half to one third of the book value. This situation will certainly decrease the attractiveness of taking in organic manures like slurries and FYM, as it is possible that the product will supply much less than the book value.

However, a change to the phosphorous availability level in all organic manures saw the availability percentage reduced from 100% in 2014 to 50% on all Index 1 and Index 2 soils thereafter.

One important change to previous regulations allows for pig and poultry manure which is imported onto a holding in the closed period in 2018 to be treated as inventory for application in 2019. To avail of this farmers must notify DAFM by 31 December. This is normal for all slurry or manure movement between farms but Seamus indicated that a new on-line manure export system will be launched early in 2019. As with the paper version, this must show details such as the date of movement, the type of manure and the quantity. It must also be signed by the importer and exporter.

‘The public tells us’

Brendan Cooney is senior executive scientist in the environment section of Wexford County Council and he emphasised that the application of manures must be done in a way that is good for the ecological and chemical status of the soil. He also said that while local authorities are charged with implementing pollution legislation, they do not have the manpower to be everywhere at the same time to ensure the law is upheld.

However, he went on to emphasise that councils do know what farmers and others are doing because local authorities receive numerous calls daily from the general public to report activities that are taking place. He said they will be bombarded with calls once the season for a field activity opens. So when slurry spreading opens or hedge cutting begins or anything else that the public can identify, they will instantly get on the phone to report it.

While Brendan acknowledges that recycling is the best use of all organic manures, he also emphasised that it is the obligation of local authorities to ensure good water quality. He reminded us that the recent EPA report indicated that water quality (N&P status) is deteriorating.

While acknowledging that incidents of severe pollution, like those that happened over two decades ago, are now virtually non-existent, the fact that water quality is deteriorating remains a concern.

Nitrate level in surface water remains an issue, especially in the main tillage regions. But Brendan acknowledged that agriculture is not the only source of this pollution and stated that there are many villages around the county that do not have a sewage system. “The blame for pollution belongs to society,” he stated.

He said current complicated legislative controls are not working for society and that the councils would really like to engage with people to get ideas on ways and systems that might work better in practice. He said that the system should be much more interactive and responsive to the needs of local groups.

Recycling is best

Brendan said that manures and organic fertiliser sources fit well into nutrient management planning and acknowledged that they play a very important role in improving soil health. Improved soil health and structure can help to prevent nutrient run-off by scouring nutrients and pollutants out of percolating water. So if agriculture played its part to the maximum it could begin to point a finger at others who fall short, Brendan commented.

This also holds for municipal sludge which is best used on the land to recycle nutrients. While we must watch for heavy metals, Brendan commented that Irish sludge is mainly processed human excrement and so is generally not a significant source of heavy metals. Its sensible use of the land should be promoted and not demonised, he said.

Buffer zones and pesticides

One increasingly important issue is adherence to buffer zones when spreading all types of manures. This is always a minimum of 5m from a surface water entity and much more from lakes, rivers, houses and water abstraction points. But a number of speakers pointed out that the minimum 5m buffer from surface water doubles to 10m in the two weeks prior to the spread closing date and after the new season opens. Minimum buffers will alter depending on the materials being spread.

Brendan also pointed out the need for continuous care with pesticides to keep them out of surface and ground water systems.

Botulism a serious issue

This is a serious issue for all farmers and is associated with the use of poultry litter on land. Botulism is one of the world’s deadliest toxins and very small doses can be lethal. The problem arises from the decay of animal flesh and is most often associated with dead birds in poultry litter. All guidelines state that litter sources which contain bird carcases must not be spread on the land.

That said, poultry manure free of carcases is a valuable soil fertiliser. There are many guidelines that pertain to its use, including the fact that it should not be tipped in fields prior to its application and that cattle should not be allowed out on to treated fields until there has been rain post-application. And there is the stated obligation to incorporate immediately post-application.

The transfer of the disease was mainly considered to be through the movement of poultry carcases by birds or vermin. This has long been considered as the main threat to neighbouring livestock and perhaps that was the case.

But more questions must now be asked. Seamus Barron from DAFM indicated that new guidelines are being drawn up to help prevent problems from the associated risk of spreading poultry litter and broiler litter in particular.

A number of high-profile cases in 2018 have emphasised the seriousness of this problem. These mean that tillage farmers will be very reluctant to take this product, leaving incineration as the only other option for its disposal. It is a great product for tillage land but the risks are more than most farmers will be willing to take for the sake of their livestock farming neighbours.

There are a number of issues that should be considered in the new guidelines. Firstly there are sources of botulism other than poultry litter, as evidenced recently by the incidence of animal deaths thought to have been caused by the presence of a dead bird in a water trough.

Dust spread

The question must be asked about the importance of dust rather than carcases as a spread vector. While this is not yet listed on official documentation, the advice now being given is to move grazing animals at least one field away from where litter is being spread. Some believe that the dust generated during spreading could be a source of botulism spread. This dust can be subsequently ingested, either through grazing or through animals licking their coats.

The advice not to graze land adjacent to a field where litter is spread until after rain had washed the foliage clean may have been even more relevant this year. Could the number and severity of animal deaths in 2018 be highly influenced by the lack of rain through the spreading season?

Another factor here is the increasing dryness of litter at the point of spread. Systems used to dry litter to make it more cost-effective for transport may be adding to the risk and the problems. If we could spread dry material during rain, would the risk of direct botulism spread be reduced?

One last comment. If dust is a disease spread risk, we must take exceptional care when a load is being tipped. It is normal to see a plume of dust rising from the top of a tipping trailer as a vortex is created as the load spills out. Could this process represent a high risk because this dust will emanate from a high point, making it easier for it to travel greater distances?

The simple advice is to inform your neighbours of any risk, especially those at risk from the prevailing winds at the time, and request them to move their grazing animals at least one field away from the spread point.

  • Deteriorating water quality in rivers sends a signal that existing control measures are not working.
  • Recycling of organic manures is a great way to utilise their nutrients to maximum effect but this must be done in a very controlled way.
  • Rural dwellers regularly inform local authorities as to what is happening on the land.
  • Botulism represents a severe threat to the continued use of poultry manures on tillage land.