AD Digestate

[Brisel]

I'm new to the forum and would like to know what the farmers out there think about using digestate out of AD plants. If anyone has used it or would like to use it, instead of the costly chemical fertilisers!

I would consider it, yes. I already import circa 10,000 tonnes of organic matter every year as PAS100 green compost, sewage digestate cake & horse/cow/chicken manure.

The key bit is calculating the cost/benefit of the fertiliser value plus unquantifiable organic matter value, minus direct costs of buying it, spreading & the soil damage of compaction from the application machinery.

Would you consider an umbilical system with a nurse tank fed by artic tankers? A good source of low cost storage for you as a producer is an ex dairy farmer with a slurry lagoon you can fill all year round then thye can spread it when soil/crop conditions are suitable. It would be worth talking to the Environment Agency about the implications of using old slurry towers/lagoons under SAFFO regulations vis a vis storing industrial wastes. Another benefit would be for said ex dairy farmer to grow your feedstock & ensile it in their old silage clamps.

 

[tesma]

We do use a nurse tank and umbilical system to spread the fields, to reduce the compaction damage that tankers can course to the soils. As i work for a company that deals with a LOT of waste. We have found it is the best and quickest way to move it.

 

[tesma]

[QUO"beefandsleep, post: 1540352, member: 4148"]Are we talking about liquid digestate?[/QUOTE]
Yes liquid digestate.

 

[tesma]

QUOTE="kill, post: 1540404, member: 622"]Still depends on how huffing big the tanker is. As one lot I have heard of is using a 4500 gallon tanker and makes ruts when it's dry.[/QUOTE]
Umbilical cord is the way forward!

 

[Robigus]

I'm new to the forum and would like to know what the farmers out there think about using digestate out of AD plants. If anyone has used it or would like to use it, instead of the costly chemical fertilisers!

So you using any chem fert?

I would be fascinated to see a fertilizer that was not made up of chemicals.

Can i just say digestate is better than pig slurry! ! If you have the chance to try it, then do. The digestate I've see spread works no end. What is feeding the AD plant?

I sell it at £24/ac and we put it on very even. Who do you get it from?

What is the chemical analysis of your digestate?
What rate are you applying it at?
Does the £60/Ha include spreading?

We are lucky as Thames Water will deliver and spread for free around here.

 

[beefandsleep]

Website says foc. But in all seriousness, there is a serious shortage of land available to dispose of Digestate waste. Nobody should be paying for the stuff. In fact for winter storage farmers could be getting a gate fee for every load as well as spreading on an foc basis.

 

[tesma]

Ahlstrom is foc (potash product ) the web site is getting up date. The digestate, the cost does include spreading. If you have storage for it over the winter months and you spread it yourself it can be foc. The digestate is a valuable fertiliser that is why there is a cost. The product can save farmers money, and test we have done are very pleasing, more to the point the farmers haven't used chem fert, saving them money!

 

[Lincsman]

A lot of blackgrass infested whole crop wheat went to AD last summer, anyone know if any seeds would be killed in the process?

 

[tesma]

I would be fascinated to see a fertilizer that was not made up of chemicals.




What is the chemical analysis of your digestate?
What rate are you applying it at?
Does the £60/Ha include spreading?

We are lucky as Thames Water will deliver and spread for free around here.

For the £24/ac we apply bout 13t/ac 2700g/ac and yes it does include spreading. For that you'll get 100u/N, 16u/P, 21u/K and 10u/S.
If you get Thames Water for free then good!

 

[beefandsleep]

Ahlstrom is foc (potash product ) the web site is getting up date. The digestate, the cost does include spreading. If you have storage for it over the winter months and you spread it yourself it can be foc. The digestate is a valuable fertiliser that is why there is a cost. The product can save farmers money, and test we have done are very pleasing, more to the point the farmers haven't used chem fert, saving them money!

Without a doubt it is a useful product, it has good levels of availiable N. But even foc it is not cost free to the farmer as some compromise has to be made in spreading accuracy and coverage. Compaction and rutting is an issue even with an umbilical system as you would expect with the application of a high volume liquid product. Ground conditions rarely permit early spring applications and misses and overlaps , especially on headland turns can lead to some very uneven looking crops. These are the main reasons you struggle to get rid of it, as well as the fact that it is produced year round at a constant flow so has to find a home even in winter come what may.
Farmers providing a service to the waste disposal industry need to be aware that they are needed far more than the waste you are trying to shift is needed. Even spread on a foc basis it is a cheap option for you as you are well aware.

 

[tesma]

Without a doubt it is a useful product, it has good levels of availiable N. But even foc it is not cost free to the farmer as some compromise has to be made in spreading accuracy and coverage. Compaction and rutting is an issue even with an umbilical system as you would expect with the application of a high volume liquid product. Ground conditions rarely permit early spring applications and misses and overlaps , especially on headland turns can lead to some very uneven looking crops. These are the main reasons you struggle to get rid of it, as well as the fact that it is produced year round at a constant flow so has to find a home even in winter come what may.
Farmers providing a service to the waste disposal industry need to be aware that they are needed far more than the waste you are trying to shift is needed. Even spread on a foc basis it is a cheap option for you as you are well aware.

You make some very good points. I do understand compromise has to be made. This is why i work very hard to keep the compromise to the farmers to a minimum.

 

[Wastexprt]

Is there any truth in the german experience that it can contain high levels of heavy metals ?

Not from analyses I've seen, certainly way below that of sewage sludges and other 'industrial' wastes. Having said that I have seen some very high PTE levels in pig slurry.

 

[Simon C]

Does no one consider the implications off inoculating their soil with methane producing anaerobic bacteria as in digestate. To get good biology in the soil you need aeroibic bacteria and beneficial fungi, digestate is doing the opposite. When we get a wet time in the winter there will inevitably be periods when there is very little air in the soil, these bacteria will take advantage of the conditions and proliferate massively, eating your organic matter and breathing out methane. Methane is highly toxic to living roots, it will kill them stone dead along with the whole plant if they are all effected.

 

[Brisel]

If the environment the anaerobic bacteria are applied to isn't beneficial to them won't they just die out?

 

[Simon C]

If the environment the anaerobic bacteria are applied to isn't beneficial to them won't they just die out?

Only ten percent of them will be active at any one time, the rest will be dormant, waiting for their ideal conditions to feed and breed. Bacteria never die, they just get eaten by something else so if you can guarantee aerobic conditions continuously, their population will gradually decline but a week say of rain and anaerobic conditions and the opposite will happen.

 

[The_Swede]

I've always been put off stubble applications in front of winter crops in terms of possible N losses against N-Max limits, this coupled with @Simon C 's description now makes this seem like a doubly bad idea - has its place in drying spring conditions perhaps, up until end of tillering?

 

[Wastexprt]

I've always been put off stubble applications in front of winter crops in terms of possible N losses against N-Max limits, this coupled with @Simon C 's description now makes this seem like a doubly bad idea - has its place in drying spring conditions perhaps, up until end of tillering?

AD digestate shouldn't be applied to stubbles in front of winter crops, unless the crop is OSR, as there is no N requirement. It's main window is from spring on arable and in split applications through the grass growing period. It's the same as bagged fertiliser, if the crop isn't able to use the nutrients why put them there?

As for the methane angle, once digested the methane content should be very low, I have some figures somewhere) so shouldn't cause a problem.

 

[Lawless]

A lot of blackgrass infested whole crop wheat went to AD last summer, anyone know if any seeds would be killed in the process?

As I understand it the seeds are only killed if it has been pasteurized.
Only AD plants that take food waste would have to pasteurize the digestate. I might be wronge.

 

[Brisel]

AD digestate shouldn't be applied to stubbles in front of winter crops, unless the crop is OSR, as there is no N requirement. It's main window is from spring on arable and in split applications through the grass growing period. It's the same as bagged fertiliser, if the crop isn't able to use the nutrients why put them there?

As for the methane angle, once digested the methane content should be very low, I have some figures somewhere) so shouldn't cause a problem.

How much available N (ammonium, nitrate, ureic) is there in AD digestate typically?

 

[Wastexprt]

How much available N (ammonium, nitrate, ureic) is there in AD digestate typically?

The ones I deal with range from 80 - 99% depending on inputs.