Organic matter %

[jack6480]

Hi
I’ve had all my fields soil tested this year and have had the organic matter tested to. All the fields have come back around 3% or 4%
I’m wondering how do you measure 1% organic matter? How many tons per acre is 1%?

Thanks

 

[Brisel]

Loss on ignition?
Soil type?

 

[Flat 10]

I'll have a stab. If you are talking the top 20cm and assuming soil weighs 1kg/litre (its probably more like 1.3 but i don't know) that's 200kg a square metre which 2000t/ha.
1% of 2000t is 20t..... Its a start anyway.
Article on measuring soil OM in the yellow peril this week.......
Perhaps its more useful than people think?!!
I will be burned at the stake for suggesting such things probably.

 

[Humble Village Farmer]

Work out the per ha dry weight of soil in the field, to the depth you have tested, say 20cm. Divide that figure by your percentage and that will give you tonnes per ha.

So say 10,000 X .2 = 2000m3

2000 x 1.4 tonnes per m3 = 2800 tonnes

2800 X .04 (or 4%)= 112 tonnes of om

Does that sound about right?

1.4 tonnes per m3 is a guess. You would have to dig a hole with measured dimensions to get anywhere near

 

[Fish]

A good AV of the sp gravity of soil is around 2.5.
Eg, one cube = 2.5 t

 

[Flat 10]

A good AV of the sp gravity of soil is around 2.5.
Eg, one cube = 2.5 t

Really? I thought sand was approx 1.4 as above. How can soil be so much more?

 

[Fish]

Really? I thought sand was approx 1.4 as above. How can soil be so much more?

Sorry , you are correct, complete brain fart on my part, got sp gravity and sp weight mix up.

 

[Flat 10]

Sorry , you are correct, complete brain fart on my part, got sp gravity and sp weight mix up.

Happens to us all!

 

[Hindsight]

Hi
I’ve had all my fields soil tested this year and have had the organic matter tested to. All the fields have come back around 3% or 4%
I’m wondering how do you measure 1% organic matter? How many tons per acre is 1%?

Thanks

Why do you want to know? What is the relevance?

 

[jack6480]

Why do you want to know? What is the relevance?

just wondered

 

[Sonoftheheir]

Reminds me of the time organic veg was really being pushed (probably early 90’s) we’re on black fenland and my grandad got the figure of 20% of our soil was organic, so he had “Grown in 20% organic soil” printed on our potato bags. I think he was trying to tap into the organic market!