Characterization of Compost from Reusable Industrial Streams: : physical, Nutrient, and Microbial Properties

Abstract: The increasing global population, combined with soil degradation, poses challenges to food security, and raises concerns about the excessive and long-term use of conventional fertilizers. Evaluating sustainable alternative by-products for their soil-improving properties could offer a potential solution, particularly for Swedish fruit producers who can tap into local waste streams as a circular source of plant nutrients. The main objective of this study is to investigate the quality of a one-year-old compost derived from different ratios of spent mushroom compost (SMC), apple waste and wood chips. As these materials originate from waste streams of agricultural practices, three different compositions were used to assess the individual impacts of the materials on quality. A series of tests were conducted to measure the physical properties, chemical content, and microbial growth to determine the current status of the compost, and its suitability as a fertilizer in fruit production. The study found that no significant difference in physical and microbial quality could be observed, leading to the conclusion that the characteristics of the composted materials had been partly neutralized as an effect of decomposition rates. This suggests that the ratios of the mixed materials did not have a substantial effect on overall compost quality. However, the results of pH and EC measurements showed that the combination of SMC, apple waste and wood chips potentially could stabilize the high salinity levels of SMC after one year. Another finding revealed that there were significant differences in nitrogen concentration, particularly in the treatment with the highest proportions of SMC. This specific treatment demonstrated higher nitrification rates compared to the others. This study aims to lay the groundwork for investigating alternative by-products as potential sources of fertilizer. Further research is required to explore the soil amending qualities of the compost when used as a growing medium, and its effects on apple cultivation. By conducting additional studies in this area, a more thorough understanding of the compost’s potential as a growth medium and its impact on apple crops can be obtained.