Mols of Nitrogen etc Something for you agronomists.

[JohnDeere8530]

I have a 800t pile of organic plant material from a nursery on my farm. An analysis report states in it has 2500mmol/kg DS of Nitrogen in it.

I wish to apply this next year on the freshly drilled OSR crop (have EA permission) However I am struggling with the amount of Nitrogen I will be applying

2500mmol/kg… I take that as to mean 2500 x10^-3 moles of Nitrogen per 1kg of dry material
Therefore this equates to 2.5mol/kg DM
Nitrogen has a RAM of 14 so that equates to 35g of N/kg (From memory of my chemistry days)
Therefore applying 800t (800,000kg)

=800,000*35grams of N
=28,000,000gm of N
=28t of N

But that assumes it is 100% dry, ( I think by looking at lab report)
So if it is 10% dry that is

approximately 2.8t of N in the 800t pile.

Is that correct?

It is possible I may be a power of 10 out somewhere though !!

 

[MNBVCXZ]

If I were you I would get the analysis re sent in something you can understand.

 

[JohnDeere8530]

i like a challenge lol

 

[John Slejpner]

your math and assumptions look good to me

 

[Luke Cropwalker]

I would get it re-tested at a lab such as Lancrop. The figure required for top dressing your OSR in the Autumn would be the ready available N rather than the total N. The available N will then be subject to field losses depending on how and when it is spread and the dry matter of the material.

 

[e3120]

I like this sort of challenge too. All I can say is that if your interpretation of the mmol/kg bit is correct, then the maths looks good from there on. At one stage you have 35gN/kg DS which is 35kg/t or 3.5kgN/t fresh weight. This would certainly be plausible, compared with FYM etc.

 

[Brisel]

Compost has minimal available N. Dose rates are limited by Total N in a NVZ but there's wriggle room if you're not doing this regularly on the same patch of land etc.

I can't and won't help on the maths here because @Luke Cropwalker is correct - it needs a more relevant test, which is hardly expensive given the tonnage and benefits.

 

[Flat 10]

I don’t think you need anymore testing other than perhaps a self oven dried sample to find out moisture content. What you have written makes sense.....