Organic Farming · July 2025 · 5 min read
Organic fertilizers release nutrients more slowly than synthetic options, building soil biology while feeding crops. Choosing the right source depends on nutrient needs, cost per unit, and availability in your region.
Blood meal (12-0-0) provides fast-release organic nitrogen, while feather meal (13-0-0) breaks down more slowly over several months. Composted poultry manure (3-2-2) supplies balanced nutrition at lower cost per ton but requires higher application volumes. Chilean nitrate (16-0-0) offers quick availability but is restricted to no more than 20% of total crop nitrogen under NOP rules.
Bone meal (3-15-0) and rock phosphate (0-3-0) are primary organic phosphorus sources, with bone meal being more plant-available. For potassium, sulfate of potash (0-0-50) mined from natural deposits is NOP-approved, and greensand (0-0-3) provides slow-release K along with trace minerals. Wood ash supplies both potassium and calcium but should be applied carefully to avoid raising soil pH excessively.
Calculate application rates based on soil test results and nutrient analysis of your organic source, since nutrient content varies between batches. Organic nitrogen typically costs $1.50–$3.00 per pound compared to $0.40–$0.60 for synthetic urea. Offset higher costs by crediting legume nitrogen from cover crops and building soil organic matter to improve nutrient cycling over time.
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