Analyzing organic amendments, such as manure, compost, digestate and biosolids, has always been recommended for macro-nutrients, but there is more to manure than just N-P-K. Significant micro-nutrients, organic matter and other elements are also present, and can reveal additional cost savings or management precautions.

An analysis does not give a lot of detail about the effect or the impact of the organic amendment on soil microbial activity. Soil microbial activity is important for its role in decomposition of crop residue and mineralization of nutrients. The larger and more diverse the microbial community, the greater the potential for soil microbial activity and enzyme process in increasing nutrient mineralization and nutrient cycling.

Table 1 provides an example of a solid analysis (compost material) and a liquid manure analysis (hog manure). The analysis report generally comes back in percentages and part per million (ppm). What do these numbers mean, and how can that information be used to enhance the value of the organic amendment? The "Available Nutrients" columns reveals the nutrients contained in the material based on Ontario guidelines. The comments column gives additional detail.

Table 1 - Comparing and Interpreting the Results of an Organic Amendment (Manure) Sample

  Solid (Compost) Liquid (Hog manure) Comments
 
Analysis
Available
Nutrients
(lbs/ton)
Analysis
Available
Nutrients
(lbs/ton)
  
Dry Matter %
76.6
1,532
4.7
470
  
Total Nitrogen (N) %
2.78
 
Organic N 14.9 + 4.5 NH4-N = 19.4
0.38
Organic N 15.9 + 3.4 NH4-N = 19.2
 
 Total N - NH4-N = Organic N

Organic N is slow release with microbial activity
ranging from 5 - 30 % depending on:
· Timing of application
· C:N ratio
· soil/weather conditions
NH4-N is readily available, but easily lost through volatilization. Same day incorporation provides ~ 75% of NH4-N
NH4-N (ppm)
(ammonium-
nitrogen)
3,003
2,114
Phosphorus (P) %
0.62
22.8 (P205)
0.13
23.9 (P205)
 · Assumption that P in manure is ~ 80% as available over time as commercial sources; where 20% is tightly tied to soil or lost in runoff or erosion

Total P% x 1.84 x 100 = lbs/1000 gal available P205
Total P% x 1.84 x 20 = lbs/ton available P205.
· Where soil fertility low, the full amount of P may not be available immediately after application and additional P205 may be needed (commercial sources).
Potassium (K) %
0.77
16.6 (K20)
0.10
10.8 (K20)
 · Assumptions that K in manure is ~90% as available over time as commercial sources

Total K% x 1.08 x 100 = lbs/1000 gal availableK20 .
Total K% x 1.08 x 20 = lbs/ton available K20.
 
Organic Matter %
51.6
791
3.5
16.5
 · Available OM is reported as dry material returned to the soil
· Existing soil organic matter levels will impact nutrient uptake/cycling/loss and water holding capacity. Where manure is applied regularly, soil organic matter levels are usually higher
 
Carbon
~ 500
 
~ 85
 
 · Organic N x Carbon value from C:N ratio - gives a rough estimate. Organic carbon measurement can also be requested from a lab analysis
pH
 
5.8
7.5
 
 · Ammonia volatilization occurs because NH4-N in manure or solution is converted to dissolved NH3 gas. More N is volatilized as pH and/or temperature increases
· Some Digestate materials and Lystek have high pH and high ammonium-N and are subject to high N loss from volatilization when not immediately incorporated.
 
C : N ratio
 
10 : 1
5 : 1
 
 · Carbon to Nitrogen ratio indicates how quickly carbon breakdown may occur.
· Nitrogen is the food source for microorganism breaking down carbon.
· C:N ratio ~ 10:1 is similar to soil conditions
· C:N ratio over 25:1 (i.e. high bedding manure) could result in nitrogen from the soil being tied up to break down carbon and cause N deficiency
Bulk Density
455 kg/m3
28.41 lbs/ft3
1,062 kg/m3
66.3 lbs/ft3
 · Bulk Density is important considerations when planning for amendments that are being transported and applied.
· Bulk density of broiler manure/compost materials are generally 25 lb/ft3 where solid cattle manure with high bedding will often be greater than 50 lbs/ft3
To convert: kg/m3 x 2.2 ÷ 35.31 = lbs/ft3
Sulphur (S) (ppm)
3966
7.9
314
3.1
 · Significant portion as organic S - slow release with soil microbial activity
· Regular application of manure will generally provide adequate S for crop requirements.
· In-frequent application may not provide enough S for canola or alfalfa crops especially in cool - wet soil conditions
EC (conductivity) (ms/cm)
15.68
20.1
12.95
83
 All salts - K, NH4, Mg, Ca, Al and including sodium (Na)
· EC and Sodium (Na) both measure salt content.
· Both materials have a high salt content and would cause potential injury (seedling/germination) if planting occurred too quickly after application or if material was surface applied (no-till) and conditions were very dry.
 
Sodium %
0.86
17.2
0.04
4.0
Aluminum (ppm)
1726
3.5
38.9
0.4
 · Micro nutrients are reported as they exist in the organic amendment.
· Availability for crop uptake varies with soil conditions, soil microbial activity, organic matter levels and existing fertility.
· Generally in the year of application, about half of the sulfur, calcium and magnesium is available
· About two-thirds of the boron, copper, iron, manganese and zinc is available for crop uptake.
Boron (ppm)
20.4
0.04
2.4
0.02
Calcium (%)
3.98
80
0.13
13
Copper (ppm)
41.3
0.08
36
0.4
Iron (ppm)
1970
3.9
113
1.13
Magnesium (%)
0.43
8.6
0.07
7.0
Manganese (ppm)
90.9
0.18
19
0.2
Zinc (ppm)
385.5
0.77
61
0.61

To convert to metric: lbs/1000 gallons ÷ 10 = ~ kg/m3, lbs/ton ÷ 2 =~ kg/tonne, ppm ÷ 10,000 = %