Slurry Management & Planning - Epizym Slurry Digester A Natural Solution To Organic Waste Streams For Cattle And Pig Slurry Tanks And Lagoons

Top ten tips for slurry management
with FACTS registered slurry Specialist Giles Dadd

An introduction to Epizym
Company focus
The science behind Epizym
Dr. Howard E. Worne
Stuart Aitkenhead, Managing Director
Giles Dadd, Principal Agricultural Consultant

  Epizym Ltd
  85 High Street
  Tunbridge Wells
  Kent
  United Kingdom
  TN1 1XP

T. +44 (0) 1892 506 950
F. +44 (0) 1892 506 951

Ten tips for better slurry management

Some farmers have an easier time of it than others when it comes to slurry management. Giles Dadd is a specialist in slurry treatment and is agricultural consultant to slurry additive firm Epizym. Here, he offers some good advice on how to take the hassle and smell out of slurry and turn it into a valuable asset.

1. See slurry as an asset

Slurry should not be seen as a problem but as a valuable asset. It not only adds organic matter to your soil and thus improves the soil structure, it can also increase water holding capacity and drought resistance in lighter and sandy soils. Based on recent prices for N, P and K fertilisers, the slurry produced by 100 dairy cows over the winter housing period has a potential value of almost £3,757. The slurry produced by a 1000-place finishing pig unit has a potential value of around £4,358 each year. †

2. Get the right storage system

There is an increasing amount of advice available on the BPEX and the Environment Agency websites (www.bpex.org.uk; www.environment-agency.gov.uk) on how to build new pig buildings which reduce ammonia output. Under floor slatted tanks offer the highest potential for problems due to the inadequate removal of slurry solids during the emptying process. This gives a build up of solids which results in reduced storage capacity and added cost to remove the solids. It makes sense to design systems that offer the potential to remedy problems easily, whether in lagoons, slatted tanks etc. Make sure manure storage and handling systems are as simple as possible with the minimum of potential bottlenecks. Finally, using a slurry additive can significantly reduce crusting in storage tanks and ensure pumping and mixing can be carried out quickly and easily.

3. Get your slurry analysed

It’s important to understand the nutrient content of your slurry to enable reliable fertiliser planning. It’s best to measure or at least estimate this rather than rely on guesswork. Make sure the sample taken for analysis is the equivalent of an ‘average’ of what is found in your store. To do this, take several samples from various positions within the store, mix them together and then take a representative sub sample. This can then be analysed in a laboratory or be tested with a slurry N meter or slurry hydrometer on the farm.

4. Understand the science

In very simple terms the potash is in the liquid fraction (urine based), the phosphate is within the solid fraction. The nitrogen is bound up in the solids fraction and in bacteria within the bacterial biomass (the volume of bacteria), as well as appearing in the liquid fraction. The availability of the nutrients to crops varies, but as a simple rule of thumb for untreated slurries, take up of potash is around 90%, phosphate 50% and nitrogen between 5% and 50%.

Losses of these nutrients will vary, but losses of phosphate and potash are low unless it is applied to coarse sands/gravels, applied through cracks or subsoil channels direct to field drains, or if it is surface spread and then washed off the field through heavy rain. Nitrogen on the other hand is easily lost through volatilisation of gaseous nitrogen to the atmosphere, and is leached out of the soil and gaseous loss (ammonia) from storage tanks. Application timing, method and amount applied at any one time are important to try to minimise losses.

5. Prepare your slurry properly

Significant savings on bought in fertiliser can be made if you maximise the fertiliser value of your slurry. Trial data from tests carried out in the UK and Europe shows that using a slurry additive can increase total-N in pig slurry systems by as much as 33% and ammonia-N by as much as 57%. In cattle slurry systems, the figures are 11% and 51% respectively*. Using an additive can liquefy your slurry, making the consistency more even, and thus nutrient application more even on your land. Thinner slurry also means less time and energy spent on mixing and pumping, as surface crust and floor solids are greatly reduced.

John Pidsley, Cheshire

John runs 60 black and white milkers and 30 youngstock on his farm in Ledsham. He says, “slurry treated with Epizym additive is so much easier to handle. There is very little crust and it has a more even consistency, even before mixing. This has greatly reduced the time and energy spent stirring the stores before spreading (it only takes me an hour to an hour and a half now), reducing hassle and allowing us to take advantage of weather windows for spreading.”

He continues, “when I put the thinner slurry on the land I saw that the grass was growing noticeably quicker almost straight away. So much so, that by the springtime, I was able to drastically reduce the amount of fertiliser I put onto the land, buying only a couple of bags as an ‘insurance policy’ almost.” John saves over £4,000 a year by using Epizym.

6. Spread it at the right time

Smell and crusting had become issues for Perry Beard, who runs a dairy herd of 140 on the outskirts of a village near Gloucester. “I’d had complaints about smell when I was spreading the slurry onto the land.” After using Epizym I could see a noticeable difference in the crust – it had halved in thickness. When the umbilical contractors came, I didn’t tell them about using it. However, the difference in the slurry was so apparent, they commented on it as well as on the significant reduction in smell when spreading.”

7. Apply it evenly, using the right machinery

Slurry application must be of an even consistency to ensure nutrient applications are also even across the field. There are four main types of slurry distribution systems: broadcast spreader, band spreader, trailing shoe spreader, and injector. Using injectors or band spreaders will reduce ammonia loss and odour nuisance and enable more even spreading of slurry.

8. Keep the smell down

New IPPC regulations focus on odour control, making this a key focus for pig and poultry farmers. However, there’s a lot that can be done to minimise smell. For example, using a slurry additive can reduce odour by up to 55%*. Check the wind direction when spreading, and if your farm is in a residential area, don’t spread at the weekends or in the evening when people are at home. Finally, don’t spread slurries at rates in excess of 50 m3/ha.

9. Use it correctly for what you farm

Silage grass requires much more potash than phosphate, making cattle slurry ideally suited. Using manures on grazing land can lead to problems such as rejection or recycling disease. Plan applications well in advance to maximise the use of your storage capacity, cropping, slurry nutrient values, soil types and keep within regulations. Calculate the supply of nutrients from your slurry, soil nutrient status, crop requirement for each field to give additional nutrients needed from the fertiliser bag.

10. Keep up to date with regulation

Rules surrounding the storage and use of slurry are being updated regularly e.g. NVZ maximum rates of manure nitrogen per hectare per year. Keep abreast of these changes and update storage systems and processes in line with them to avoid cautions or expensive fines.

† Source: Calculated using slurry output figures from RB209, DEFRA guidance booklet, 7th edition.

* Source: Increased total-N in pig slurry systems by as much as 33% and ammonia-N by as much as 57% - Silsoe Research Institute, Olfactometer Unit. In cattle slurry systems, the figures are 11% and 51% respectively – UK Dairy Research Farm