Frass 101

From biology to best practices—everything you need to get started.

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Frass is a biologically rich soil amendment that contributes organic matter, chitin, and a living microbiome.

This section covers definitions, typical composition, how frass works in soil systems, recommended application ranges, and answers to common questions.

Frass 101

  • Frass is the excrement of insects, primarily produced in insect farming operations. It contains partially digested feed, insect exoskeleton fragments (chitin), and a diverse community of beneficial microbes.

    • Average N-P-K ranges: 4% N, 2% P, 2% K, however values range based upon insect species and diet.

    • Organic matter typically >60%.

  • Frass enhances soil health by increasing microbial diversity, supplying slow-release nutrients, and adding chitin, which can prime plant defense mechanisms.

    • For field crops: 200-500 kg/ha pre-plant incorporation recommended.

    • For greenhouses: 50-100 g per plant at transplanting.

  • Frass is best categorized as an organic soil amendment, but it can provide measurable nutrient contributions.

  • Properly processed frass is unlikely to attract pests; it should be stored dry and applied in accordance with recommendations.