Covering Slurry lagoons??? Good thing or not???

delilah

Member
Just how does covering a slurry pit help with emissions? Unless the methane is taken off as in a digester surely it’s still there waiting to enter the atmosphere at some point.

The rate of loss of methane from a slurry store will depend on the temperature more than anything else. The bugs that produce it perform best at cow body temperature, and produce very little at winter temperatures.
Ammonia is a different story, it is split between ammonia (which readily evaporates) and ammonium ions (which stay in the slurry). The higher the pH, the greater proportion as ammonia, and the same with temperature. As ammonia is lost from solution, more ammonium will be converted into ammonia, but the lower the proportion as ammonia the slower that will be.

Note that the y axis of the graph is a log scale, so going from pH 8 to pH 5.5 is a thousand fold reduction.

I think the best way to reduce ammonia losses is to reduce pH with sulphuric acid (cheaper than buying sulphur as Double Top or ammonium sulphate), rather than covering lagoons. I am part way through developing a system for our AD digestate.


the methane is the product of digesting slurry. As far as i know, and i am not an 'expert', no methane comes from an open slurry store.
In fact, little ammonia evaporates until spread. There is a study on spreading which found - the runnier the slurry being spread, the less the ammonia evaporates.


Trying to get my head round this.
What is gained, in terms of emissions, by putting a cover on your slurry store ?
 

som farmer

Member
Livestock Farmer
Location
somerset
Trying to get my head round this.
What is gained, in terms of emissions, by putting a cover on your slurry store ?
stops things falling in and drowning ?
it's meant to keep the gasses in the lagoon, but does seem a bit funny.
been looking at the problem, was thinking of a separator, a good friend sells these systems, his honest advice, unless you have a mechanical person, on farm, to look after it, do not go down that root. That knocks that out then.
Was thinking about crust etc, slurry bugs etc, the cheapest, easiest way to get rid of your crust, spray it with silage effluent, next, buy a stirrer. The effluent, hard to believe, anybody else telling me, l would doubt. So l to am having different thoughts, you have to take cover off, to either spray or stir, surely you let all the gasses out then ?
We use a top fill pump, fills tankers up in 4/5 minutes, and can mix it very well, that goes on maize ground, let some water build up, umbilical the rest.
then, we cannot use a spreader plate...........
Rather think quite a lot of farmers, will find it difficult to fully comply, or even ignore it, especially the removal of aut spreading. And am quite sure, it isn't going to work quite like some f############# idiot, who devised it.
 
Last edited:

glow worm

Member
Location
cornwall
dont see how any sort of floating or tarpaulin cover can work on a lagoon or tower if you bed on sand as no amount of stirring moves it all and it has to be dug out. Roof over with shed yes to keep out rainwater but it would need to be very high to accommodate digger and wouldn't stop emissions.
 

som farmer

Member
Livestock Farmer
Location
somerset
It’s the blind leading the blind whilst in the dark on a foggy night.

Where do they think all these thousands of slurry lagoon covers/covered towers are suddenly going to appear from?
china ?
where, after they invade tawain, but so much is made there, virtually everything will stop working, so we cannot afford to fall out,
But, its going to be a bloody nightmare.
1st lot goes on maize ground, ( they want to stop us growing that ) 2nd after silage, any thing else under autumn reseeds.
Even with grants, many cannot afford to spend serious money on ever tightening regulations, on slurry. The only light on the horizon, price of fert, controls on sh1t, will lead to lower production, which might push prices up, so we can afford it.
 
More to the point, what is the fudging point of covering lagoons when you are all going to go out on the first dry day in spring and spread the fudging stuff?

A bit of rain water does no harm besides costing you money to spread and haul the stuff.

That EA chap in this area is a PITA.
 

som farmer

Member
Livestock Farmer
Location
somerset
More to the point, what is the fudging point of covering lagoons when you are all going to go out on the first dry day in spring and spread the fudging stuff?

A bit of rain water does no harm besides costing you money to spread and haul the stuff.

That EA chap in this area is a PITA.
ollie, please don't be so polite about the ########### ############ ##### EA man, in this area. When his boss came out, he was fine.
Many farmers, including us, treat slurry as a bit of a nuisance, get as much under maize as we can, and spread the rest on grass/arable ground,
But it is a valuable product, more so with fert price, and NVZ has perhaps shown us that it is valuable, and we need to use it more carefully, to save us money, still a pia though.
The new regs are a bigger pia, but they do actually look good theory, and l rather suspect some idiot devised them, with no idea of the practicality of actually doing them, and sold the idea to those above him, who definitely have no idea.

like you, l cannot see any logic in covering a lagoon, then spreading it all over ground, the next stage, trailing shoe, dribble bar or injecting, looks to negate that, at more expense.
if we remove cover, and stir/agitate, you can smell if from quite a distance, surely that smell, is the 'emmissions' ?
 

Stinker

Member
The rate of loss of methane from a slurry store will depend on the temperature more than anything else. The bugs that produce it perform best at cow body temperature, and produce very little at winter temperatures.
Ammonia is a different story, it is split between ammonia (which readily evaporates) and ammonium ions (which stay in the slurry). The higher the pH, the greater proportion as ammonia, and the same with temperature. As ammonia is lost from solution, more ammonium will be converted into ammonia, but the lower the proportion as ammonia the slower that will be.

Note that the y axis of the graph is a log scale, so going from pH 8 to pH 5.5 is a thousand fold reduction.

I think the best way to reduce ammonia losses is to reduce pH with sulphuric acid (cheaper than buying sulphur as Double Top or ammonium sulphate), rather than covering lagoons. I am part way through developing a system for our AD digestate.
View attachment 833288

Could you add the acid where the liquid comes off the separator. Maybe use some sort of dosatron device to make it accurate.
 
The rate of loss of methane from a slurry store will depend on the temperature more than anything else. The bugs that produce it perform best at cow body temperature, and produce very little at winter temperatures.
Ammonia is a different story, it is split between ammonia (which readily evaporates) and ammonium ions (which stay in the slurry). The higher the pH, the greater proportion as ammonia, and the same with temperature. As ammonia is lost from solution, more ammonium will be converted into ammonia, but the lower the proportion as ammonia the slower that will be.

Note that the y axis of the graph is a log scale, so going from pH 8 to pH 5.5 is a thousand fold reduction.

I think the best way to reduce ammonia losses is to reduce pH with sulphuric acid (cheaper than buying sulphur as Double Top or ammonium sulphate), rather than covering lagoons. I am part way through developing a system for our AD digestate.
View attachment 833288
I'm sure ive asked this before but how much sulfuric acid is needed per cube of slurry?
 

sjt01

Member
Mixed Farmer
Location
North Norfolk
Could you add the acid where the liquid comes off the separator. Maybe use some sort of dosatron device to make it accurate.
We add the acid pre-separator in a mixing tank, so we stop ammonia loss from the solids as well. The issue is then it tends to clump the fibres, making it hard to pump. We have found that only a piston pump (e.g. Houle) can cope after many tries.
I'm sure ive asked this before but how much sulfuric acid is needed per cube of slurry?
It was supposed to be 5 kg/m3, but I find it to be about 16 kg to get to pH5.5 on our digestate. It will depend on the starting pH (we are about 7.8) and the buffering capacity of the slurry. We cannot get any more second user acid at the moment, and virgin acid is up to £750/tonne which makes it uneconomic.
 

Cowski

Member
Location
South West
Acidification is part of the next productivity grant
I wonder if this is a signal that government are leaning towards acidification rather than covering lagoons?

I’m sceptical about acidification as I don’t think the impact on the slurry and soil biology is well understood and I think it relies on an on farm process would be difficult to enforce
 

frederick

Member
Location
south west
I wonder if this is a signal that government are leaning towards acidification rather than covering lagoons?

I’m sceptical about acidification as I don’t think the impact on the slurry and soil biology is well understood and I think it relies on an on farm process would be difficult to enforce
Talking to someone yesterday it was available last time round. Probably more relevant to pig producers and there current permitting requirements it may become a direction of travel but not with acid at those prices.
It has double benefits as it lowers ammonia and methane.
 

Slowcow

Member
I wonder if this is a signal that government are leaning towards acidification rather than covering lagoons?

I’m sceptical about acidification as I don’t think the impact on the slurry and soil biology is well understood and I think it relies on an on farm process would be difficult to enforce
I was wondering this, raising pH of the soil is hard enough here. Spreading slurry at pH 5.5 instead of 7ish has got to have an effect?
Or is the nutrient benefit greater than the effect on soil pH?

Will be a while before ofandg approve it anyway :ROFLMAO:
 

nonemouse

Member
Location
North yorks
I wonder if this is a signal that government are leaning towards acidification rather than covering lagoons?

I’m sceptical about acidification as I don’t think the impact on the slurry and soil biology is well understood and I think it relies on an on farm process would be difficult to enforce

It’s been fairly common practice over in Holland for over 30 years, surely there must be plenty of details on the longer term effects on soil biology from over there?
 

sjt01

Member
Mixed Farmer
Location
North Norfolk
Anyone on here involved in the DEFRA Co-design on slurry/ammonia? I know @Janet Hughes Defra is very busy at the moment but it would be great to get an update on the direction of travel on all of the clean-air/slurry stuff
I have been involved with some of it, mostly on how to regulate, how to arrange grant schemes, very little technical. We are now going to do smaller groups, some on regs, some on grants etc.
 

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Man fined £300 for bonfire-related waste offences

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Written by William Kellett from Agriland

court-640x360.jpg
A man has pleaded guilty at Newtownards Magistrates’ Court to waste offences relating to a bonfire next to the electrical sub-station on the Circular Road in Newtownards, Co. Down.

Gareth Gill (51) of Abbot’s Walk, Newtownards pleaded guilty to two charges under the Waste and Contaminated Land (Northern Ireland) Order 1997, for which he was fined £150 each and ordered to pay a £15 offender’s levy

On June 25, 2018, PSNI officers went to Gill’s yard, where they found a large amount of waste consisting of scrap wood, pallets, carpet and underlay.

Discussion with Northern Ireland Environment Agency (NIEA) officers confirmed the site...
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