Ontario labs accredited for OMAFA soil testing use similar methodology and report results with “as-is” or “as-applied” percentages or ppm for macro and micronutrients. Table 1 provides details for interpreting the results of a manure analysis and calculations used to determine available nutrients. OMAFA’s AgriSuite nutrient management software tools includes an organic amendment calculator that will provide available nutrients, micro nutrients and N-P-K equivalent value of manure using database or actual analysis numbers combined with application and timing management details. The Field Management tool allows a user to complete a nutrient management plan for a single crop or crop rotation using soil test and crop removal data, yield goals, nutrient credits from previous crops or organic amendments and fertilizer applications to determine rotational and/or longer-term nutrient balances. Available Nutrients and Value for Manure from Various Livestock Types summarizes total and available nutrients from liquid and solid manure based on manure dry matter ranges and/or specific groups within livestock types. Figure 1 provides a snapshot of these tables.
The traditional manure analysis measures dry matter, total nitrogen (TN), ammonium nitrogen (NH4-N), total phosphorus, and total potassium. These results will provide the estimated crop available N – P2O5 – K2O but can vary based on application timing and incorporation details.
Manure phosphorus (P)
Manure phosphorus is composed of inorganic phosphorus which is plant available and organic phosphorus which is bound to the organic components of the manure and must be mineralized by the soil microbes. In the year of application, the available phosphorus is comparable to commercial phosphorus sources. 80% of the phosphorus in manure is considered available for a crop. However, for fields with low fertility, applied manure P may not be mineralized in time to meet early season crop needs, especially in prolonged cool, wet conditions. Up to 20% of the phosphorus in manure is assumed to be bound clay particles or to soil minerals (e.g., calcium, iron, aluminum), and/or lost to the environment through water movement (runoff, tile water) or erosion.
Manure potassium (K)
The potassium (or potash) in manure is mainly in inorganic form, is not bound to soil particles, is soluble, and quickly available for uptake by plants. The potassium in manure varies by livestock species and by rations. Although potassium is not an environmental issue, it is important to be aware of the potassium in manure for nutrient balancing. Low soil K, especially on dairy operations, can result in K deficiencies in crops. Alternatively, high soil K levels can lead to high K levels in forages and when fed to cattle before calving can interfere with calcium metabolism and lead to milk fever.
For both phosphorus and potassium, the lab analysis is provided as a percent total P or K. This percentage is converted to percent P2O5 and/or K2O and then adjusted to estimate the portion that is crop available.
Secondary and micronutrients in manure
Secondary nutrients – calcium (Ca), magnesium (Mg), and sulphur (S), – as well as micronutrients – boron (B), copper (Cu), iron (Fe), manganese (Mn) molybdenum (Mo), and zinc (Zn) – are essential to plant growth and are part of livestock rations. They are present in manure and if analyzed in a manure sample, can provide insight to potential commercial fertilizer savings. Aluminum (Al) and sodium (Na) can also be analyzed, especially in biosolids (often high in Al and Fe) and compost (often high Na).
| Table 1. Interpreting Manure Analysis Results | ||||||||
| AgriSuite is a collection of on-line tools for nutrient management planning, including manure www.agrisuite.omafra.gov.on.ca | ||||||||
| Units | Analysis | ~Available Nutrients | Comments | |||||
| Solid | Liquid | lbs/ton | lbs/ 1000 gal | |||||
| Dry Matter | % | 41 | 8.6 | 820 | 86 | Analyses are reported “as-applied” or “dry matter basis” As-applied ÷ (reported DM/100) = DM basis example: 0.82 N ÷ (41% DM/100) = 2 % N DM basis | ||
| Total Nitrogen (N) | % | 0.82 | 0.38 | Available Organic N + Available NH4-N = total available N | Total N – NH4-N = Organic N Organic N is slow release with microbial activity ranging from 5 – 30 % depending on: Timing of applicationC:N ratio soil/weather conditions NH4-N is readily available, but easily lost through volatilization. Same day (spring) incorporation provides ~ 75% of NH4-N | |||
| NH4-N (ammonium- nitrogen) | ppm | 1100 | 1600 | 2.5 | 1.8 | |||
| Phosphorus (P) | % | 0.21 | 0.09 | 7.7 (P205) | 17 (P205) | Manure contains inorganic and organic P and is considered about 80% crop available over time. Where soil fertility is low, the full amount of P may not be available immediately after application and additional P205 may be required. Total % P x 2.29 = % P205 | ||
| Potassium (K) | % | 0.66 | 0.10 | 14 (K20) | 11 (K20) | K in manure is mainly in inorganic form and readily available, therefore assumed that K in manure is ~90% as available over time as commercial sources Total K% x 1.2 = % K2O | ||
| C:N ratio | 25 : 1 | 11:1 | C:N ratio indicates how quickly carbon breakdown may occur. Nitrogen = food source for microorganisms breaking down carbonC:N ratio over 25:1 (i.e. high bedding manure) could result in short-term soil N deficiency | |||||
| Organic Matter (OM) | % | 42 | 18.5 | 345 | 159 | OM is about 58% organic carbon (%OC x 1.724 ≈ %OM)Existing soil organic matter levels will impact nutrient uptake/cycling/loss and water holding capacity. Soil OM levels are higher where manure is applied regularly. OC is the carbon component of OM and provides a good estimate of total OMConversion relationship: % Organic Carbon = % OM x 58 | ||
| Organic Carbon (OC) | % | 24 | 11 | ~ 200 | ~ 90 | |||
| pH | 8.0 | 7.0 | 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. | |||||
| Bulk Density | kg/m3 lbs/ft3 | 455 kg/m3 28.4 lbs/ft3 | 1,062 66.3 | 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 | 1,200 | 320 | 2.4 | 3.2 | Significant portion as elemental S – slow release with soil microbial activityRegular application of manure will generally provide adequate S for crop requirements. Spring or infrequent application may not provide timely release for winter cereals, canola or alfalfa crops especially in cool – wet soil conditions | ||
| EC (total salts) | ms/cm | 10 | 14 | 13 | 90 | Total salts – K, NH4, Mg, Ca, Al and including sodium (Na) EC x ~640 = ppm EC and Sodium (Na) both measure salt content. Materials with a high total salts content could cause potential injury (seedling/germination) if planting occurs too quickly after application or if material was surface applied (no-till) and conditions were very dry. | ||
| Sodium (Na) | % | 0.86 | 0.06 | 17 | 6 | |||
| Aluminum (Al) | ppm | 1200 | 154 | 2.4 | 1.5 | Micronutrients are reported as they exist in the organic amendment. Availability for crop uptake varies with pH, 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. In acidic soils, soluble phosphorus reacts with aluminum and iron to become insoluble and unavailable for plant uptake. | ||
| Boron (B) | ppm | 6 | 4 | 0.012 | 0.04 | |||
| Calcium (Ca) | % | 1.3 | 0.35 | 26 | 35 | |||
| Copper (Cu) | ppm | 24 | 15 | 0.05 | 0.15 | |||
| Iron (Fe) | ppm | 990 | 210 | 2 | 2.1 | |||
| Magnesium (Mg) | % | 0.31 | 0.11 | 6.2 | 11 | |||
| Manganese (Mn) | ppm | 95 | 30 | 0.19 | 0. 3 | |||
| Zinc (Zn) | ppm | 85 | 36 | 0.18 | 0.36 | |||
| Metric/Imperial conversions: | ppm ÷ 10,000 = % | lbs/ton ¸ 2 = ~kg/tonne | lbs/1000 gallons ¸ 10 = ~kg/m3 | |||||