Harvesting is well under way and it will not be long until planting begins again. With more growers appreciating the many benefits of poultry litter and that sector undergoing expansion it is important that we use it wisely and judiciously. The amount of lodging around in spring barley emphasises one of the merits of catch crops to fertility.

We are also seeing the benefit of having additional fertility in the ground, albeit resulting from the poor yields last year in many instances.

It is important to match the manure type with the objective

For those attempting to build organic matter and improve soil health, the addition of organic manure is more than worthwhile.

But it is important to match the manure type with the objective, which could be fertiliser replacement for a specific crop, or soil organic matter increase.

This article focuses on the use of poultry litter for two main reasons:

There is no questioning the value of litter as a source of nutrients, coupled with its yield enhancing characteristics. But with its use comes the risk of botulism. There are substantial guidelines available on the proper use of litter, regarding transport, storage and spreading from the Department of Agriculture and these were updated this year: https://www.agriculture.gov.ie/animalhealthwelfare/diseasecontrol/botulism/

There is a general acknowledgement of the value and benefits that these products bring, especially to the tillage sector.

Currently we produce an estimated 145,000t of broiler litter in Ireland from approximately 90m broilers

I took the opportunity a few weeks ago to meet with some of the people from the Department who oversee these controls and regulations to discuss the guidelines and the critical factors.

Currently we produce an estimated 145,000t of broiler litter in Ireland from approximately 90m broilers. This is a significant resource for use on tillage farms and access to it must be protected.

The problem

While it is of considerable benefit for tillage farmers, broiler litter in particular represents a unique threat to other livestock proximate to the area of spreading. For this reason, it is important to understand what the problem is and how it moves about and this formed the basis of the discussions I had with the Department people.

My first thing to learn was the nature of how the disease and animal deaths manifest themselves.

Ultimately, it is caused by a bacteria called Clostridium botulinum. This bacteria grows on decaying flesh (it can originate from plant material also) and in doing that it produces a potent toxin which is deadly when ingested. Generally, all that enters the affected animal is the toxin.

There are seven different types of botulism toxins depending on their source and different ones affect different species

We call the disease and death associated with Clostridium botulinum, botulism. The disease arises following the ingestion of neurotoxin which is deadly to the ingesting animal. The occurrence of botulism in Ireland is most often associated with cattle and broiler litter but it has also been a problem in wild birds.

There are seven different types of botulism toxins depending on their source and different ones affect different species. Even small pieces of carcase or a dead rodent are enough to contaminate a silage pit and such instances have been a serious issue.

While diagnosis of death can be indicated by clinical symptoms, the Department emphasises the importance of using laboratory testing to confirm the cause and the particular neurotoxins involved.

There is no vaccine licensed for use in cattle in Ireland, nor is there any specific treatment for the disease. The only effective control is prevention.

Preventing spread of toxins

This requires all efforts to minimise animal contact with carrion and decaying matter to help prevent ingestion of feed contaminated with decaying materials.

While the cause is generally associated with decaying animal/bird carcases, it can also be associated with decaying vegetation such as silage pits/bales, grain, or even grassland.

It is also noted that wildlife and poultry carcases produce particularly high levels of the botulism toxin.

Efforts to prevent the problem must begin in the poultry house. Technically, litter should not contain dead birds and any litter that does should not be moved to agricultural land.

If dead birds are seen as material is being loaded or tipped, that material should not go to farms

The different guidelines clearly state that anyone involved in transporting litter should not take material if there are signs of dead birds. If dead birds are seen as material is being loaded or tipped, that material should not go to farms.

Control of the disease and the acceptability of material for use in tillage land is heavily dependent on poultry producers doing their jobs. Nonetheless, hauliers and tillage farmers also have a part to play.

While you should only receive litter that is not contaminated with carcases, you should equally assume that the material contains a real danger. This is the basis of the general advice and guidelines.

Traditionally, the spread of the disease has been associated with the movement of dead carcases in wet litter but this can still occur in the drier product which is more common nowadays.

While this remains a risk, the move to dryer litter would appear to be adding another dimension to spread via the associated dust and toxin movement during tipping and spreading. And perhaps this has increased the risk of spread of the disease.

The Department guidelines also suggest the risk of spread seems to be greater when spreading in dry and windy conditions.

So, by default, it might be that damp, calm or light rain scenarios would decrease the risk of spread for any given scenario.

Good incorporation is a challenge. The Department specifies immediate ploughing down but the pressure for rapid incorporation can result in poor burial. For anyone very serious about minimising this risk, my advice would be to incorporate to three to four inches using a good disc immediately behind the spreader and then to plough this as soon as possible. Having the field cultivated will help to ensure more complete burial.

It is difficult to minimise the risk from dust, especially with dry product. The only real option is to opt to load and spread on a calm day preferably during light rain. This could prove to be a very useful option if you can make it happen.

There is always a risk when spreading fields adjacent to livestock. The guidelines recommend that users notify owners of neighbouring stock in advance of their intention to spread so they can move their stock to fields a bit further away.

One of the big challenges for users of litter is its storage.

The guidelines state that it cannot be tipped in a field and must be stored on a concrete pad away from rivers, etc. This is not an option for some farmers.

A stack must be at least 500m from grazing or housed livestock and should be completely covered to prevent access by wildlife. This is a serious deterrent where loads are arriving on farm over a prolonged period.

That said, the middle of a big tillage area is the safest place to spread the product.

Of interest though is the fact that every load should have with it a commercial document to state that the delivery is carcase-free. Users should insist on this minimum guarantee.

When and where to use

The guidelines rightly state that the product should only be spread on tillage land and not on grassland. There is also concern about its use in catch crops being grown for grazing.

The new guidelines specify a three-year application interval for litter. This could be an issue in terms of the amount of N that would be applied but I gather from the officials that this is not necessary once spreading of litter is part of a nutrient management plan.

That said, oilseed rape growers could easily opt for rotational application as this crop can directly benefit from higher autumn N fertilisation. Rape can sap up the free nitrogen to produce additional autumn growth.

This can help reduce or prevent winter pigeon damage. And the growth made by this nitrogen can help to significantly reduce the amount of bagged nitrogen needed in springtime to produce the necessary green area index of 3.5.