Manure Harvest Interval Calculator
Application date to earliest organic harvest day.
What it does
Organic rules put a clock between raw manure and harvest: 90 days when crops avoid soil contact, 120 when they touch it. The date math is trivial; missing it fails certification.
The tool above adds the right wait to the application date in UTC and names the rule. Pick soil contact for roots and leafy greens, no-contact for trellised fruit. It prints the earliest harvest day.
USDA organic standards carry the 90/120-day raw-manure clause, and extension produce-safety guides teach the same split with incorporation and recordkeeping around it. Composted manure with temperature logs plays by different rules.
Apply, incorporate within hours, write it down, and let the later of every applicable clock govern. Grazed fields, produce rules, and certifier paperwork can each push harvest past this page's date.
How to use
- Enter the manure application date.
- Pick soil contact or no contact.
- Read the earliest harvest date.
- Read the wait days and rule name.
- Log it for the certifier.
- Layer produce-safety rules on top.
Formula
- applied
- Manure application date.
- wait
- 90 no-contact, 120 soil-contact.
Soil contact means edible portions touch soil during growth: 120 days. No contact (trellised, staked) means 90 days. Dates compute in UTC at noon to dodge daylight-saving shifts; applied day counts as day zero.
Worked example
Example: Mar 1, soil contact
March 1 raw manure where harvest will touch soil.
- Raw manure applied Mar 1, 2026, crops touch soil.
- Rule is the 120-day soil-contact wait.
- Mar 1 + 120 days = Jun 29, 2026.
- Tool prints Mon Jun 29 2026, 120 days.
- Incorporate fast and log it for the certifier.
Reference table
| Contact | Wait | Examples |
|---|---|---|
| Soil contact | 120 days | Roots, leafy greens, melons |
| No contact | 90 days | Trellised fruit, staked crops |
| Composted right | Per compost rules | Temperature-logged piles |
| Grazed | Rolling | Harvest waits restart |
Limits
- Organic raw-manure rule only. Compost differs.
- Produce-safety law can extend waits.
- Grazing restarts clocks continuously.
- Certifier paperwork decides disputes.
Common mistakes
- Counting the applied day as day one.
- Using 90 days for ground crops.
- Forgetting grazed-field deposits.
- Skipping incorporation and records.
- Ignoring produce-rule overlays.
Try it yourself
Quick checks. Answers sit tucked under each question.
Apr 15 application, no soil contact?
90-day rule: Apr 15 + 90 = Tue Jul 14 2026.
Dec 1 application, soil contact?
120-day rule: Dec 1 + 120 = Tue Mar 31 2026.
Questions
90 or 120 days: which applies?
90 days where harvest avoids soil contact (trellised fruit), 120 where it touches (roots and leafy greens). Raw manure only; properly composted manure follows compost rules instead.
Does this cover composted manure?
Untreated animal manure under organic rules. Compost made to temperature-turn schedules with records is a different input with its own waiting logic.
What records does the certifier want?
Incorporate within hours, keep setbacks from water, and log dates, sources, and fields. Certifiers read records first and stories never.
Does produce safety law change this?
No. Fresh produce rules layer on top with their own microbial standards and ag-water testing. Both clocks can run; the later harvest date wins.
Do grazed fields count as applied?
Yes. Grazing livestock deposit fresh manure continuously, so harvest waits restart around rotations. Plan grazing gaps before cutting or picking.
Which date wins with several inputs?
The later of the two dates. Biological, chemical, and certifier clocks all bind; harvest only when every one has expired.