|
Table 3. Method of calculating ammonia N availability
of biosolids and manurea |
|||
|---|---|---|---|
|
Available Nitrogen % |
Time of Application |
Days Until Incorporatedb |
|
|
NH4
|
Organic
|
Date
|
Days
|
|
50
|
33
|
Nov-Feb
|
<= 5
|
|
25
|
33
|
Nov-Feb
|
> 5
|
|
50
|
33
|
Mar-Apr
|
<= 3
|
|
25
|
33
|
Mar-Apr
|
> 3
|
|
75
|
33
|
Apr-Jun
|
<= 1
|
|
25
|
33
|
Apr-Jun
|
> 1
|
|
75
|
15
|
Jul-Aug
|
<= 1
|
|
25
|
15
|
Jul-Aug
|
> 1
|
|
25
|
33
|
Sep-Oct
|
<=1
|
|
15
|
33
|
Sep-Oct
|
> 1
|
| a Biosolids injected immediately may have 100% of
the ammonia nitrogen available in the year of application if injected when
the plants can readily use this form of nitrogen. The calculations are for
all animal manures. It is assumed that 50% of the organic N in poultry manure
is converted to NH4 rapidly and is therefore included in the
NH4 column for calculating available N. b Incorporation is the mixing of manure and soil in the tillage layer. Disking is usually enough tillage for conserving N availability. |
|||
| Source: The Ohio State University Bulletin 604 | |||
| The general formula for calculating available nitrogen in manure and biosolids is: |
|---|
|
Available N lb/ton = O.N x (efficiency factor) + A.N x (efficiency factor) + nitrate nitrogen ammonium nitrogen = NH4 - N Available N = 38.18 lb/ton organic N X 0.30 efficiency factor + (5.58
lb/ton) ammonium nitrogen X (0.50 efficiency factor). (This example will
be surface applied if we were to inject or plow-in the efficiency factor
would be greater.) |
| Key O.N. = organic nitrogen A.N. = ammonium nitrogen |
Mineralization of organic nitrogen varies considerably with soil type and environmental conditions.
Table 4 illustrates the dramatic reduction in organic nitrogen over time. In most cases, it would not be necessary to account for residual organic nitrogen applications made more than two years ago.
|
Table 4. Estimated mineralization rates (Kmin) for
organic nitrogen of different sewage sludges and manurea |
||||||
|---|---|---|---|---|---|---|
| Fraction (Kmin)* of Organic N Mineralized From the Following Sludges: | ||||||
|
Time After Sewage Sludge Application (Years) |
Animal |
Unstabilized Primary and Waste |
Aerobically Digested |
Anaerobically Digested |
Composted |
Lime Stabilized |
|
0-1 EF1
|
----
|
0.40
|
0.30
|
0.20
|
0.10
|
0.15
|
|
1 -2 EF2
|
0.05
|
0.20
|
0.15
|
0.10
|
0.05
|
0.05
|
|
2 -3 EF3
|
0.047
|
0.10
|
0.08
|
0.05
|
----b
|
----
|
|
3 -4 EF4
|
0.045
|
0.05
|
0.04
|
----
|
----
|
----
|
|
4 -5 EF5
|
0.043
|
----
|
----
|
----
|
----
|
----
|
|
5 -6 EF6
|
0.041
|
----
|
----
|
----
|
----
|
----
|
| * Fraction of the sludge organic N (Org-N) initially applied,
or remaining in the soil, that will be mineralized during the time interval
shown. Kmin values are provided as examples only and may be quite
different for different sewage sludges, soils, and climates. Therefore,
site-specific data, or the best judgment of individuals familiar with N
dynamics in the soil-plant system, should always be used in preference to
these suggested Kmin values. a Applications of organic wastes in July and August may have as little as one half of the mineralization rates posted in the year of application (OSU Bulletin 604). bOnce the mineralization rate becomes less than 3% (i.e., 0.03), no net gain of PAN (plant available nitrogen) above that normally obtained from the mineralization of soil organic matter is expected. Therefore, additional credits for residual sludge N do not need to be calculated. |
||||||
| Source: Sommers, L. E., C. F. Parker, and G. J. Meyers, "Volatilization Plant Uptake and Mineralization of Nitrogen in Soils Treated with Sewage Sludge," Technical Report 133, Purdue University Water Resources Center, West Lafayette, Indiana, 1981. | ||||||