Compost Atlas

Citations & Sources

Every coefficient, rate constant, and field convention used in the calculator — with the specific source that produced it and the role it plays in the output.

← Back to Sources & methodology

On this page

  1. Mineralization kinetics & substitution ratios
  2. Soil & compost data standards
  3. Field conventions & oxide chemistry
  4. Crop nutrient demand
  5. Regulatory frameworks
  6. Internal methodology

1. Mineralization Kinetics & Substitution Ratios

Foundation for the 90-day plant-available delivery calculation. These references establish the first-order mineralization model, supply the rate constants used at California growing-season soil temperatures, and provide the calibrated substitution ratios for each nutrient.

Stanford, G., & Smith, S. J. (1972). Nitrogen mineralization potentials of soils. Soil Science Society of America Journal, 36(3), 465–472.
Foundational kinetic framework
Used for
  • First-order mineralization model: N_min(t) = N₀ × (1 − e^(−kt))
  • Establishes the labile-pool concept (N₀) that the 90-day window draws against
Hadas, A., & Portnoy, R. (1994). Nitrogen and carbon mineralization rates of composted manures incubated in soil. Journal of Environmental Quality, 23(6), 1184–1189.
Rate-constant range for composted manures
Used for
  • Rate constant k range 0.020–0.054 wk⁻¹ for composted dairy and poultry manures
  • Contributes to the adopted central value k = 0.037 wk⁻¹ at 25°C reference
Sikora, L. J., & Szmidt, R. A. K. (2001). Nitrogen sources, mineralization rates, and N dynamics for composts. In Compost Utilization in Horticultural Cropping Systems (P. J. Stoffella & B. A. Kahn, eds.), CRC Press, pp. 287–305.
N speciation in mature compost
Used for
  • N pool partitioning in mature compost: inorganic ~15%, labile organic ~40%, stable humic ~45%
  • Rate constant range 0.025–0.045 wk⁻¹ for MSW and yard waste composts
Gale, E. S., Sullivan, D. M., Cogger, C. G., Bary, A. I., Hemphill, D. D., & Myhre, E. A. (2006). Estimating plant-available nitrogen release from manures, composts, and specialty products. Journal of Environmental Quality, 35(6), 2321–2332.
PAN methodology for mixed composts (Pacific Northwest)
Used for
  • Mineralization rate range 0.020–0.040 wk⁻¹ for mixed composts
  • PAN (plant-available N) estimation methodology backbone
  • Uptake efficiency factors used in the substitution-ratio composite
Amlinger, F., Götz, B., Dreher, P., Geszti, J., & Weissteiner, C. (2003). Nitrogen in biowaste and yard waste compost: dynamics of mobilisation and availability. European Journal of Soil Biology, 39(3), 107–116.
European-source confirmation of kinetic range
Used for
  • Confirms rate constant range 0.022–0.038 wk⁻¹ for biowaste and yard waste composts
  • Supports the adopted central k = 0.037 wk⁻¹ across feedstock types
Cabrera, M. L., Kissel, D. E., & Vigil, M. F. (2005). Nitrogen mineralization from organic residues: Research opportunities. Journal of Environmental Quality, 34(1), 75–79.
Temperature correction methodology
Used for
  • Q₁₀ = 2.0 temperature-correction relationship for soil N mineralization
  • Arrhenius-derived correction: k(T) = k(T_ref) × Q₁₀^((T − T_ref)/10)
Griffin, T. S., & Honeycutt, C. W. (2000). Using growing degree days to predict nitrogen availability from livestock manures. Soil Science Society of America Journal, 64(5), 1876–1882.
Temperature-time integration validation
Used for
  • Validates Q₁₀ = 2.0 for the soil-temperature → mineralization mapping
  • Supports growing-degree-days as the integration variable for the 90-day window
Eghball, B. (2002). Soil properties as influenced by phosphorus- and nitrogen-based manure and compost applications. Agronomy Journal, 94(1), 128–135.
P kinetics + soil-fixation factor
Used for
  • P partitioning in compost: ~40% inorganic + ~60% organic (phytate, phospholipids, nucleic acids)
  • Uptake efficiency of 0.80 for P (soil P fixation losses)
  • Underpins the P substitution ratio of 0.18
Eghball, B., Ginting, D., & Gilley, J. E. (2004). Residual effects of manure and compost applications on corn production and soil properties. Agronomy Journal, 96(2), 442–447.
Multi-year residual nutrient release
Used for
  • Year 2 residual N: 7–10% of remaining organic N
  • Year 3 residual N: 3–5% of remaining organic N
  • Source for the multi-year residual strip in the calculator output
Sullivan, D. M., Bary, A. I., Nartea, T. J., Myhre, E. A., Cogger, C. G., & Fransen, S. C. (2003). Nitrogen availability seven years after a high-rate food waste compost application. Compost Science & Utilization, 11(3), 265–275.
Long-tail residual N (multi-year)
Used for
  • Detectable N residual continuing 5–7 years post-application
  • Supports the "tail continues 5+ years" disclosure in method notes
Sharpley, A. N. (1996). Availability of residual phosphorus in manured soils. Soil Science Society of America Journal, 60(5), 1459–1466.
P availability and fixation
Used for
  • Phosphatase-hydrolysis kinetics for organic P fraction
  • Soil P fixation correction in the P substitution ratio
Castellanos, J. Z., & Pratt, P. F. (1981). Mineralization of manure nitrogen — correlation with laboratory indexes. Soil Science Society of America Journal, 45(2), 354–357.
Lab-index correlation with field mineralization
Used for
  • Confirms laboratory total-N and C:N ratio as adequate proxies for field-scale mineralization
  • Supports using C:N as the user-exposed parameter for the N substitution adjustment
Stadler, C., von Tucher, S., Schmidhalter, U., Gutser, R., & Heuwinkel, H. (2006). Nitrogen release from plant-derived and industrially processed organic fertilizers used in organic horticulture. Journal of Plant Nutrition and Soil Science, 169(4), 549–556.
Micronutrient release order in organic matrices
Used for
  • Affinity order: Cu > Fe > Zn > Mn — explains the descending micronutrient substitution ratios
Whalen, J. K. (2014). Managing soil biota-mediated decomposition and nutrient mineralization in sustainable agroecosystems. Advances in Agriculture, 2014, Article 384604.
K dissolution kinetics
Used for
  • Potassium release primarily dissolution-driven, not mineralization-driven
  • K substitution ratio of 0.68 reflects dissolution from a largely water-soluble K pool (60–80% of total K)
Sullivan, D. M., & Miller, R. O. (2001). Compost quality attributes, measurements, and variability. In Compost Utilization in Horticultural Cropping Systems (P. J. Stoffella & B. A. Kahn, eds.), CRC Press, pp. 95–120.
Compost quality variability bounds
Used for
  • Background on compost variability that drives the calculator's per-batch lab-input requirement
  • Establishes that batch-level testing is required for defensible nutrient management

2. Soil & Compost Data Standards

Standardized analytical methods and data sources the calculator consumes.

USDA Natural Resources Conservation Service (NRCS). Soil Survey Geographic Database (SSURGO) and Soil Data Access (SDA) REST API.
Source: sdmdataaccess.sc.egov.usda.gov · Produced through the National Cooperative Soil Survey
Used for
  • All pre-treatment soil baseline data: pH, OM%, CEC, texture, bulk density, drainage class, available water capacity
  • Depth-weighted horizon aggregation source data per cokey
  • Mapunit identification (mukey) from lat/lon via SDA_Get_Mukey_from_intersection_with_WktWgs84()
U.S. Composting Council (USCC). Test Methods for the Examination of Composting and Compost (TMECC). Compost Research and Education Foundation (CREF).
Source: compostfoundation.org/TMECC · compostingcouncil.org/page/TMECC
Used for
  • Compost input schema methodology citations: 02.02 (bulk density), 03.09 (moisture), 04.02 (N species), 04.05 (acid-digest total elementals), 04.10 (electrical conductivity), 04.11 (pH), 05.07 (OM by LOI; CCE), 05.08-B (stability respirometry)
  • Standardizes the compost analytical inputs the calculator accepts
U.S. Composting Council. Seal of Testing Assurance (STA) Program. Compost quality benchmarks.
USCC STA general-use compost specifications
Used for
  • Warning thresholds: pH 5.5–8.5 (acceptable range), OM 30–65%, EC ≤ 5.0 dS/m on TMECC 04.10-A basis
  • Stability classification (very stable / stable / moderately unstable / unstable) per respiration rate

3. Field Conventions & Oxide Chemistry

Conventions for reporting nutrient amounts in NRCS-compatible field units.

USDA NRCS. Conservation Practice Standard 336 — Soil Conditioner.
NRCS Field Office Technical Guide
Used for
  • Output units convention: lbs/acre for nutrient additions
  • Oxide-form reporting convention: P₂O₅, K₂O, CaO, MgO; elemental S
  • Integration-depth defaults (6 in standard)
USDA NRCS. Conservation Practice Standard 590 — Nutrient Management.
NRCS Field Office Technical Guide
Used for
  • Annual PAN (plant-available N) framework comparison — calculator's 90-day window deliberately diverges from the annual framework (which overstates by 30–40% for rowcrop), as documented in method notes
  • Cumulative-loading rate compliance reference
Standard oxide molecular-weight ratios (universal physical chemistry).
Periodic-table molecular-weight derivations
Used for
  • P → P₂O₅: × 2.29   (MW P₂O₅ ÷ 2·MW P)
  • K → K₂O: × 1.20   (MW K₂O ÷ 2·MW K)
  • Ca → CaO: × 1.40   (MW CaO ÷ MW Ca)
  • Mg → MgO: × 1.66   (MW MgO ÷ MW Mg)
  • S: reported as elemental S per NRCS convention

4. Crop Nutrient Demand

Sources for the seeded crop nutrient demand database.

Hart, J., Sullivan, D. M., Anderson, N. P., Hulting, A. G., Horneck, D. A., & Christensen, N. W. Crop Fertilizer Guide. Oregon State University Extension Service.
OSU Extension publications · CropFertilizerGuide_Aug_26_2017
Used for
  • Nutrient demand rows for the 10-crop v1.0 reference set (field corn, winter wheat, alfalfa, pasture grass, processing tomatoes, strawberry, potatoes, soybeans, bluegrass/turf, leafy greens)
  • 90-day window demand vectors for N, P₂O₅, K₂O, S
University of California Agriculture and Natural Resources. Manure and Compost Application to Cropland Guidelines. UC ANR Publication 21505.
UC ANR publication catalog
Used for
  • California-specific cropping system context for the substitution-ratio framework
  • Validation of the irrigated rowcrop assumption

5. Regulatory Frameworks

Regulatory references for compliance context and cumulative metal loading.

U.S. Environmental Protection Agency (1993). 40 CFR Part 503 — Standards for the Use or Disposal of Sewage Sludge.
U.S. EPA · ceiling concentrations and pollutant limits
Used for
  • Cumulative metal-loading thresholds: Zn 2,800 mg/kg ceiling, Cu 4,300 mg/kg ceiling
  • Source for the warning logic when compost metal content approaches regulatory limits
California Department of Food and Agriculture (CDFA). Healthy Soils Program Technical Documentation and compost application guidelines.
CDFA Office of Environmental Farming and Innovation
Used for
  • California-specific compost-amendment incentive and reporting context
  • Annual PAN framework comparison (the framework the calculator's 90-day model diverges from for in-season planning)

6. Internal Methodology

Internal technical documents that bridge published literature to the operational calculator coefficients.

Compost Nutrient Substitution for Synthetic Fertilizers — 90-Day Rowcrop Rotation, California Conditions, Mature Compost at C:N = 15. Internal technical memorandum, May 2026.
Synthesizes the literature above into operational ratios
Used for
  • All 11 base substitution ratios in the calculator: N (0.20), P (0.18), K (0.68), Ca (0.50), Mg (0.50), S (0.17), B (0.51), Zn (0.11), Mn (0.15), Fe (0.05), Cu (0.06)
  • C:N interpolation anchors: 12 → 0.24, 15 → 0.20, 20 → 0.15
  • Application-method adjustment: surface application × 0.75 on N (NH₄⁺ volatilization)
  • Multi-year residual N coefficients: Year 2 ~8.5%, Year 3 ~4% of remaining organic N
  • California Central Valley operating assumptions: 23°C mean soil temperature, 90-day rowcrop window, incorporated pre-plant baseline