Unlocking the Value of Layer Manure
Layer units have significantly increased in size over the past听decade, producing听large volumes of manure.听With significant growth in free range eggs recently, we are now seeing new poultry sheds springing up around the country, this also means that availability of layer manure or听鈥榟en pen鈥櫶齱ill increase. While there are some farmers who may shy away from using it,听it鈥檚听reputation as听鈥榬ocket fuel鈥櫶齣s well deserved, with听relatively small听applications capable of supplying good levels of nutrients very quickly. As margins tighten, could hen pen offer an opportunity for your business to reduce fertiliser costs?听听听听听
Most poultry farmers realise the value of their hen pen and will try to utilise as much as they can on their own holdings although volumes produced will, in many cases be greater than can be spread on the holding. There are also holdings with听very little听additional听land and will need to export much听if not听all of听their manure production.听听
Layer manure听contains听high levels听of听several听nutrients and unlike other听farmyard听manures听(FYM), nutrient availability听is higher.听While standard values can be a useful starting point,听just听like other manures getting a sample of the hen pen analysed can give a much more听accurate听indication听of nutrient content.听This allow applications to be better targeted and avoid unnecessary over-applications.听
Using the standard values from听Scotland鈥檚听Farm Advisory Service听(FAS)听technical听note听鈥淥ptimising the application of livestock farmyard manures and slurries鈥�,听one tonne听of layer manure听contains听the following nutrients听with the availability to the following crop also shown:
*Depends on incorporation timing (over or under 24 hours), soil type听and time of year of application.
Nitrogen availability to the following crop can vary significantly听due to听a number of听factors including time of year, speed of incorporation, soil听type听and ground cover. Around 30-50% of the total nitrogen is potentially readily available to crops, being in the forms of uric acid and ammonium-N.听Unfortunately听this also听means that it is more susceptible to losses听both听to the air through volatilisation听and听through leaching听meaning that careful planning is听required听to get the听optimum听benefit from the application and to minimise losses to the environment.听听
Most of the听phosphate and听potash will be available to the growing crop, with the听remainder听being added to soil reserves. Good levels of听sulphur are also found in layer manure, with some available to the crop. Layer manure will also supply good levels of听magnesium, although this should听mainly be听thought of as helping听maintain听soil reserves.听As with all manures, applications should be planned in tandem with using soil analysis听and it is important that pH is at recommended levels. When soils are at a lower听than听optimum听pH, nitrogen and phosphate will not be utilised efficiently, increasing the risk of nutrients being wasted and lost to the environment.听听听
Taking this a stage further, what does this mean at field level, both in terms of nutrients听and also听financially?听Taking typical application rates of 6.25t/ha (2.5 tons per acre) being applied in the spring onto听a grass field听with听an organic mineral soil, the following nutrients are supplied听with their financial value also shown at current fertiliser prices:听
Using layer manure offers the opportunity to supply good levels of nutrients although there are听several听considerations.听
Due to its听high level听of readily available nitrogen, there are several restrictions听for those in听Nitrate Vulnerable Zones听(NVZ)听areas听in terms of storage, application听timings听and rates as well as periods of the year when no spreading can occur to reduce the risk to the environment. Planning timing of applications and requirements beforehand can therefore help decide when to take it onto farm, particularly if storage is an issue.听Records must also be kept of any imports onto farm along with spreading dates and rates etc.听听
Spreading should be undertaken in an even manner, avoiding lumps left lying in fields. No grazing should be undertaken for at least four weeks after an application.听Consult with听the latest听Farm Assurance scheme guidance, to ensure compliance when applying听layer manure as a fertiliser.听
Layer manure offers an opportunity for farmers to access an excellent source of nutrients which can provide a quick response in grassland and arable crops alike. With global influences meaning that fertiliser prices are rising significantly with availability also becoming challenging,听perhaps it听is time to consider giving hen pen a try.听听
George Chalmers, Senior Consultant,听George.Chalmers@sac.co.uk
Posted by Unearthed News on 17/04/2026
