Soil Fertility (Organic Standards)

Soil fertility under the NOP isn't just about feeding the crop — it's a system-level requirement to maintain or improve the physical, chemical, and biological condition of soil over time. The rule lives in NOP §205.203 and shapes a substantial part of any crop OSP.

What the regulation requires

The producer of an organic crop must:

• Use tillage and cultivation practices that maintain or improve soil condition and minimize erosion
• Manage crop nutrients and soil fertility through rotations, cover crops, and the application of plant and animal materials
• Manage plant and animal materials to maintain or improve soil organic matter content in a manner that does not contribute to contamination of crops, soil, or water by pathogens, heavy metals, or residues of prohibited substances

What's allowed as a fertility input depends on whether the substance is on the National List, plus restrictions on raw manure timing.

Allowed inputs

The most common allowed soil fertility inputs:

• Composted plant and animal materials — meeting the NOP composting standard (specific C:N ratio, time/temperature requirements)
• Raw manure — allowed but with a critical timing restriction (see below)
• Compost teas — typically allowed if from compliant compost
• Cover crops — green manures, especially legumes for nitrogen fixation
• Allowed soil amendments — listed in NOP §205.601, including some forms of mined gypsum, elemental sulfur, certain rock phosphates

The raw-manure timing rule

Raw manure may be applied to organic crops, but with a 120-day pre-harvest interval for crops where the edible portion contacts the soil (lettuce, root vegetables, low-growing fruit) and a 90-day pre-harvest interval for crops where the edible portion does not contact the soil (tree fruit, sweet corn).

This is one of the most-checked items at inspection. Records must show the application date, the field, the manure source, and the harvest date.

Prohibited

• Synthetic fertilizers — urea, anhydrous ammonia, triple superphosphate, blended NPK products (unless the specific product is on the National List)
• Sewage sludge / biosolids — prohibited even though "natural"
• Burning crop residues, except as a way to suppress disease or stimulate seed germination

What documentation is required

The OSP and field records must include:

• The fertility plan — what's applied, when, at what rate
• Crop rotation plan and actual rotations (often spanning 3+ years)
• Cover crop history
• Soil test results (most certifiers want them periodically; some require them annually)
• For each application: date, field, material, rate, source, harvest interval observed

Why it matters

Soil fertility noncompliances are common because the rule rewards system thinking and punishes shortcuts. An operation that applies manure inside the pre-harvest interval, plants nutrient-demanding crops without rotation, or uses an off-list amendment risks suspension of the affected parcels.