Aged Manure vs Composted Manure: What's the Difference?

Wikipedia: ManureClemson Cooperative Extension: Composting
Verdict

Composted manure is the safer choice for vegetable gardens because the composting process kills pathogens and weed seeds through sustained high temperatures. Aged manure is simply old manure that has dried out. It may still contain viable weed seeds and pathogens. Always choose composted for food crops.

How Do Aged Manure and Composted Manure Compare?

Composted Manure wins 3 of 5 categories. The breakdown below covers pathogen safety, weed seed viability, nutrient content, effort required, food crop safety.

FactorAged ManureComposted Manure
Pathogen Safety
Composting reaches 130-160 F, killing E. coli and salmonella. Aging alone may not reach these temperatures
5
9
Weed Seed Viability
Hot composting kills most weed seeds. Aged manure may still contain viable seeds that sprout in your garden
5
8
Nutrient Content
Aging preserves slightly more nitrogen than composting, which loses some nitrogen during the hot phase
7
6
Effort Required
Aging requires only time and a place to pile manure. Composting requires turning, moisture management, and monitoring
8
5
Food Crop Safety
USDA organic standards prefer composted manure. Aged manure requires a 120-day pre-harvest wait for food crops
5
9

When Should You Choose Aged Manure?

Choose Aged Manure when you prioritize nutrient content, effort required. Aging preserves slightly more nitrogen than composting, which loses some nitrogen during the hot phase

  • Nutrient Content: Aging preserves slightly more nitrogen than composting, which loses some nitrogen during the hot phase
  • Effort Required: Aging requires only time and a place to pile manure. Composting requires turning, moisture management, and monitoring

When Should You Choose Composted Manure?

Choose Composted Manure when you prioritize pathogen safety, weed seed viability, food crop safety. Composting reaches 130-160 F, killing E. coli and salmonella. Aging alone may not reach these temperatures

  • Pathogen Safety: Composting reaches 130-160 F, killing E. coli and salmonella. Aging alone may not reach these temperatures
  • Weed Seed Viability: Hot composting kills most weed seeds. Aged manure may still contain viable seeds that sprout in your garden
  • Food Crop Safety: USDA organic standards prefer composted manure. Aged manure requires a 120-day pre-harvest wait for food crops

Sources

Source:Wikipedia: ManureSource:Clemson Cooperative Extension: Composting

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