Understanding Your Waste Report
The waste report provides information about using materials as amendments for soils and media. Incorporating these materials into a nutrient management plan can offset fertilizer costs and inputs. The waste code determines which tests will be applied to each sample.
Nitrogen (N)
This is the total concentration of nitrogen (N or TKN) in mg/kg or mg/L for solids and liquids, respectively. Nitrogen is reported on an as-received (wet-weight) basis for all liquids and for all manure-based solids. Solid Industrial by-products (e.g. paper fibers, ash, non-composted crop residues, etc.) are reported on a dry-weight basis.
Inorganic nitrate-nitrogen (NO3-N) and ammonia-nitrogen (NH4-N) are not part of the standard analysis but can be added for a fee.
Other Nutrients
Concentrations of phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), and boron (B) are reported in mg/kg for solids and mg/L for liquids. All solids are reported on a dry-weight basis. All liquids are reported on an as-received (wet-weight) basis. Molybdenum (Mo) can be added for a fee.
What is the "grade" of the waste material?
Imagine if you bought a big bag of this material, what would its fertilizer grade be? A fertilizer grade is the percentage of the nutrient in the material. To find the percentage, simply move the decimal point 4 places to the left. Let's use the example above.
| Nutrient | Nutrient Measurement from Report | Percentage |
|---|---|---|
| Nitrogen (N) | 39500 | 3.95 |
| Phosphorus (P) | 14100 | 1.41 |
| Potassium (K) | 26400 | 2.64 |
This material would have a NPK fertilizer ratio of 4 - 1.4 - 2.6. It is about 4% N, 1.4% P, and 2.6% K on a dry-weight basis.
Important note: The Agronomic Division does not actually grade fertilizer or waste products.
Estimate of Available Nutrients
The nitrogen availability estimate depends on the manure type and application method that you specify on the submission form and accounts for the fact that only 40-60% of the manure nitrogen becomes available within one year of application. The nitrogen availability calculation for specific manure types was established by the North Carolina Interagency Nutrient Management Committee. This committee adopted a conservative approach in estimating non-manure N and other nutrients. These nutrients are estimated to be 100% available. Concentrations are reported on an as-received (wet weight) basis for all elements in lb/ton for solids or lb/1000 gal for liquids.
How do we calculate the estimate of available nutrients?
The formulas used to calculate the estimate of available nutrients (or Total, depending on sample type) are below. The NAC or "Nitrogen availability coefficient" is determined by the North Carolina Interagency Nutrient Management Committee, this coefficient depends on the waste code. CF is a conversion factor needed to express P as P2O5 and K as K2O. The CF for P is 2.29 and for K is 1.20. The last variable needed is the Dry Matter Percentage (DM%), this only applies to solid waste.
| Nutrient | Solid (lb/ton) | Liquid (lb/1000 gal) |
|---|---|---|
| Nitrogen (N) (Manure) | (N ÷ 1,000,000) × NAC × 2000 | (N ÷ 1,000,000) × NAC × 8340 |
| Nitrogen (N) (Non-manure) | (N ÷ 1,000,000) × 2000 × (DM% ÷ 100) | (N ÷ 1,000,000) × 8340 |
| Phosphorus (P2O5) or Potassium (K2O) | (P or K ÷ 1,000,000) × CF × 2000 × (DM% ÷ 100) | (P or K ÷ 1,000,000) × CF × 8340 |
| Other Nutrients | (Nutrient ÷ 1,000,000) × 2000 × (DM% ÷ 100) | (Nutrient ÷ 1,000,000) × 8340 |
Carbon (C) and the Carbon to Nitrogen Ratio (C:N)
Carbon (C) is measured on solid organic materials primarily to determine the carbon to nitrogen ratio (C:N). The Carbon to nitrogen ratio is an important parameter in composting, both for feedstocks and finished product.
Is my compost "good"?
C:N
The C:N ratio and pH are important parameters for "good" compost. The carbon to nitrogen ratio (C:N) is probably the most important and affects not only the quality of the compost, but also the rate of composting. C provides energy and mass to the composting microbes, while N is crucial for their cell growth and function. An imbalance of C and N can lead to inefficient composting. An ideal C:N to start is around 25:1 - 30:1. Ratios higher than this will slow the composting process while lower ratios can lead to off-gassing of ammonia causing odors. Testing individual feedstocks can help optimize mixing ratios. Common feedstocks ratios are below.
| Materials High in C | C:N |
|---|---|
| Dried Leaves | 30-80:1 |
| Straw | 40-100:1 |
| Wood Chips and Sawdust | 100-500:1 |
| Bark | 100-130:1 |
| Paper | 150-200:1 |
| Newspaper and Cardboard | 560:1 |
| Materials High in N | C:N |
|---|---|
| Vegetable Scraps | 15-20:1 |
| Coffee Grounds | 20:1 |
| Grass Clippings | 15-25:1 |
| Manure | 5-25:1 |
From Dickson, N., T. Richard, and R. Kozlowski. 1991. Composting to Reduce the Waste Stream: A Guide to Small Scale Food and Yard Waste Composting
pH
Optimal pH for compost is between 5.5 and 8.5. As microbes turn the materials into compost, they produce organic acids which promote the growth of fungi. These acids while beneficial for dropping the pH for the fungi, can over-accumulate and lower the pH too much. As the compost nears pH 4.5, it becomes anaerobic severely decreasing the microbial activity and rate of compost. Typically all that is needed is to remedy low pH is mixing and aeration.
Other Parameters
EC (Electrical Conductivity) is reported in units of mS/cm. It measures the total quantity of dissolved salts (ions) in solution. It may be used as a general evaluation of the total nutrient concentrations available to plants. However, it also includes elements such as sodium (Na) and chloride (Cl), which increase EC without providing nutritional value. In addition, excessively high EC will burn plant roots regardless of the whether the ions are required for plant nutrition.
SS (Soluble Salts) is the same as EC, but is expressed in units of 10-5 S/cm.
pH is the level of acidity or basicity as measured by the amount of hydrogen ions (H+ ) in solution. It ranges from 0 (acidic) to 14 (basic) on a logarithmic scale; 7 indicates neutrality. It can reduce the availability of micronutrients (Fe, Mn, Zn, Cu, B) when pH is high (>6.5) and the availability of macronutrients (N, P, K, Ca, Mg, S) when pH is low (<5.0).
Bulk density (BD) is a measure of how heavy the organic material is, relative to its volume, and it reported in lb/yd3. It is an optional test that is sometimes used to measure compost quality.
CCE% (Calcium Carbonate Equivalent) represents the acid-neutralizing capacity of a material expressed as weight percentage of calcium carbonate. For waste materials with liming potential (e.g., lime-stabilized biosolids, ash, poultry layer litter), the application rate may be limited by a high CCE%. Waste with a high CCE% should only be applied at rates needed to increase soil pH to the desired target. Overapplication can lead to high soil pH, which may limit micronutrient availability.
ALE (Agricultural Lime Equivalent) indicates the amount of the sample material that provides a liming effect equivalent to one ton of agricultural grade limestone. For example, an ALE of 2 indicates that 2 tons of the sample material would have the same liming effect as one ton of limestone.
DM% (Dry Matter) is the percent of the as-received sample that is dry solids and is inversely related to percent moisture. It is used in semi-solid and solid samples to convert the dry-weight nutrient measurement concentrations (mg/kg) back to wet-weight concentrations of the original sample, which are reported in the estimate of nutrients available for first year (lb/ton).
Sodium (Na), chloride (Cl), and aluminum (Al) are elements that may be important for plant nutrition but are more often detrimental to plant health in excessive levels. Aluminum is not a plant nutrient and may create toxicity when soil or substrate pH is excessively low.
Additional Conversion Factors
lb/ton × 4.17 = lb/1000 gal.
lb/1000 gal. × 0.24 = lb/ton
Fertilizer grade (%) = mg/kg or mg/L ÷ 10,000
This page was last modified on 04/02/2026