[USCC] Soil test levels for nitrogen in compost

Tue Jul 3 16:07:04 CDT 2007

I think it's important to remember significant figures when providing
this kind of general information.  Without contesting the range you
suggest, it is inaccurate to provide nitrate and ammonia in terms of
general values down to 1 mg (or ppm if one prefers).  I think that the
nearest 50 mg/kg is the most accurate such a discussion should suggest,
and probably the nearest 100 mg/kg.  

Thus using your numbers:

NO3:  300 mg/kg
NH4:  850 or 900 mg/kg
Total N: 16,000 mg/kg

On a more specific note, Ericaceous species: blue berries, azaleas,
rhododendrons, mountain laurel, and heather as examples, absorb most
nitrogen in form of ammonium-nitrogen.  Grasses, flowering annuals,
herbaceous perennials and vegetable plants absorb most nitrogen in form
of nitrate-nitrogen.  Trees and many woody perennials tend to absorb
both equally well.

Peter Severtson
Biosolids/Composting/Soils
Department of Ecology
15 West Yakima Avenue
Yakima, WA  98902
(509) 575-2605

-----Original Message-----
From: compost-bounces at mailman.cloudnet.com
[mailto:compost-bounces at mailman.cloudnet.com] On Behalf Of frank
Sent: Tuesday, July 03, 2007 10:30 AM
To: Steve Diver; Compost Discussion List
Subject: Re: [USCC] Soil test levels for nitrogen in compost

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Steve,
Great question. The goal is to provide a steady supply of nutrients
during the growing season. When using compost we have the available
forms and the to-be available forms. Then the many site specific
considerations like soils that leach and soils that don't. plants that
need  a lot of available N and plants that need a long term slow supply.

Please see below:

Steve Diver wrote:

>Join us at the US Composting Council's 16th Annual Conference & Trade 
>Show Oakland Marriott City Center, Oakland, CA | February 9-12, 2008.
>The National forum for those involved in the development and expansion
of the composting and organics recycling industry.
>Conference Highlights, Registration forms, Exhibitor information and 
>Sponsorship Opportunities available at the USCC website: 
>www.compostingcouncil.org or call the USCC at 631.737.4931 
>_______________________________________________________________________
>_______ I'm looking for interpretive guides to understanding 
>ammonium-nitrogen in comparison to nitrate-nitrogen on lab tests for 
>soils and composts.
>
>  
>
When deciding if the soil should have high ammonia or high nitrate I
look at a few factors. Both are available but most plants seem to like
nitrate better. So when growing lettuce and other leafy green I suggest
the quick response nitrate with a continuous supply. When talking about
trees, shrubs and places where the compost nitrogen must last a long
time I look more toward ammonia and the slow conversion to nitrates
without the potential loss of nitrogen due to leaching. (nitrate
leaches).
Then if you have a high pH you will not want to add a high amount of
ammonia and high nitrates can 'burn' roots especially in low pH soils.

>For example, what are the normal ranges for L, M, H, VH. 
>  
>
Soil range for agronomic rates. (available maintained in soil ) NH4-N
from 50 to 150 lb per acre NO3-N 25 to 50 lb/acre These numbers differ a
lot depending on crop type, type of irrigation, how fertilizer is
applied, soil type,  compost

Compost
Average values for compost is:
1.61% dry wt total nitrogen
303 mg/kg Nitrate nitrogen
879 mg/kg ammonia nitrogen

In the past I wanted to group all the constituents into L, M, H VH
ranges and make a classification system.  I got no interest  and it is
more 'extra' work than I want to do now. But if you have the time and
want to do that I could send you the info you will need.

Frank

>Interpretive numbers on NO3-N is easy to find, but guidelines on NH4-N 
>seems to be scarce.
>
>And then how do you interpret the numbers in relation to soil/compost 
>activity when one is 2x-4x higher than the other.
>
>It appears that NH4-N is normally performed for manure analysis as part

>of a nutrient management plan.
>
>  
>
I think this is because during active composting and all manures there
is a huge oxygen demand. Nitrates (NO3) do not form because there is no
oxygen available for it to form. As the compost stabilizes and the
Biological Available Carbon is reduced, and there is air going through
the pile, oxygen becomes more plentiful and the NO3 can form. I think
this is good that it doesn't form until the end (curing) because
bacteria use ammonia as an available source and not NO3(?).  So if the
pile dries out too soon or there is too much aeration during the
composting process and nitrates form there may be a short supply of N
for the microbes even though there is plenty N in the pile.

>Much appreciated,
>Steve Diver
>
>
>
>
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--
Frank Shields
Soil Control Lab
42 Hangar way
Watsonville, CA  95076
(831) 724-5422 tel
(831) 724-3188 fax
frank at compostlab.com
www.compostlab.com

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Food Industry Environmental Network (FIEN), a regulatory and policy
e-mail alert service for environmental, food and agricultural industry
professionals.
Contact Jack Cooper 301/384-8287 JLC at fien.com --- www.fien.com

Opinions expressed do not necessarily represent the USCC, the
Foundation, or the Board of Directors.

Non-members of USCC are encouraged to join the Council through its
website at: http://www.compostingcouncil.org/membership.cfm

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