Biosolids photo identifier

Event Recycling


Application Rate

Biosolids Application Process

Field Evaluation

Field data include information about the:
  • Application site,
  • Field history (crop history, fertilization, and special problems),
  • Realistic yield goals and planned crop rotation,
  • Soil evaluation.
For assistance with soil sampling see,

Determine Nutrient Needs

You need to determine the nutrient needs of your crops to make sure the amount of biosolids applied doesn't exceed the agronomic rate.

For assistance with test interpretation see,

Application Rate

When designing an application program, consider the variables affecting the nitrogen cycle at the site, such as plant uptake, leaching potential, nitrogen losses, and transformations. You can adjust the application rate, timing, and method as needed for the site that meets requirements of the biosolids rule and your permit. Your goal is for crops or other vegetation to have the best possible uptake of nitrogen and no leaching below the root zone. It should be noted that all calculations are in dry tons of biosolids.

For assistance calculating biosolids application rates see,

Monitor Crop & Soil

Monitoring activities for matching biosolids nutrients to crop needs may include:
  • Residual soil nitrate and other tests after harvest, which give information on how well the nutrient management program worked.
  • Field observation, which identifies differences in plant vigor or color, or changes in pest incidence.
  • On-farm testing.
For assistance with post harvest testing see,

Biosolids Analysis

Agronomists and land managers use biosolids analysis to determine how well biosolids can satisfy nutrient needs. Only a portion of the total nitrogen content of biosolids is immediately available for plant uptake. The remainder is in an organic form that slowly becomes available to plants after application. Biosolids analysis also determines phosphorus content, which can help determine application appropriateness at any given site.

For assistance estimating available nitrogen see,

Record Keeping

Records should be in a simple, legible, reproducible format. Below is stage specific record keeping information. You may be required keep additional records, depending on the conditions of your permit coverage.

Field Evaluation
  • Retain copies of all laboratory reports for soil and water monitoring during the life of the project.
  • Describe how site and access restrictions were met. This includes
    • Waiting periods for harvest of crops and public access,
    • Buffer requirements.
Determine Nutrient Needs
One of the best ways to demonstrate the beneficial use of biosolids is to compare pre and post-application monitoring. Soil tests will show changes in plant-available soil nutrients. Plant tissue tests show changes in crop nutrient content. Soil and plant tests can also be used to compare biosolids-treated and untreated areas within the same field.

Application Rate
Maintaining agronomic rate records allows you to document that applications have met agronomic rate requirements.
  • The biosolids applied to a site, and daily records of field applications including the:
    • Application date,
    • Percent total solids,
    • Quantity applied (dry tons per acre),
    • Acreage applied.
  • Keep records of the quantity of biosolids delivered and the quantity of biosolids applied to the field. For examples see the tables below.
Example of a biosolids application record for a land application site.
Date of Report 1/1/12
Grower/Land Manager John Doe
Site or Field Number 14-C
Target Application Rate (dry tons/acre) 3.2
Total site Acreage (acres) 48.6
Target Application Rate (dry tons/site) 155.5
Actual Application Rate (dry tons/site) 147.8
Percent of Target Rate Applied (%) 95
Applied Daily Cumulative Applied
Date Wet Tons % Total Solids Dry Tons Acres Dry Tons/Acre Dry Tons Dry Tons/Acre
8/8/13 180 18.2 32.8 12.0 2.7 32.8 2.7
8/9/13 280 20.8 58.2 18.0 3.2 91.0 3.0
8/10/13 290 19.6 56.8 18.6 3.1 147.8 3.0


Biosolids Analysis
  • Certification statements: Appropriate certification statements in WAC 173-308-290 (Record Keeping) must accompany records.
  • If vector attraction reduction requirements are met at the time of application (injection or tillage) include a description of how they were met.
  • If any trace element concentration is greater than the Table 3 pollutant limits, keep the following records indefinitely:
    • Site location,
    • Area of biosolids application,
    • Date, rate, and location of biosolids applications,
    • Cumulative amount of each pollutant applied.