3.5. Agronomic testing
Approximately two dozen specific tests were conducted to measure the agronomic value of the compost sample and were presented in Table 6. The tests included nutrients, organic matter, pH, electrical conductivity etc. The analysis showed that the compost had high organic-matter content and low salt content, all of which indicate good compost characteristics. The ratio of nitrogen (N), phosphorus (P), and potassium (K), or NPK ratio, was measured at 1.6–0.9–0.7. Reported units are consistent with those found on fertilizer formulations. A sum greater than 5 is indicative of compost with high nutrient content, and best used to supply nutrients to a receiving soil. A sum below 2 indicates low nutrient content, and is best-used to improve soil structure via the addition of organic matter. Most compost falls between 2 and 5 (Thompson et al., 2003). Nutrient levels were slightly greater than expected for compost produced from naturel casings. However, compost is typically used to amend and improve soil structure as a nutrient source.