Program on the Environment

Current mulches, such as wood chips or hays, used in urban restoration are often expensive, difficult to access, and slow to decompose, creating a need for faster and more accessible alternatives. This study aimed to identify a more effective alternative to traditional wood chip mulch by comparing the effects of fruit, vegetable peels and leaves/branches on soil nutrient supplementation, moisture, pH, and temperature. During a capstone internship with the Green Seattle Partnership, data were collected weekly, measuring soil pH, temperature, moisture, and nutrient levels (N, P, K) by a 6 in 1 soil conditions tester. The results showed that fruit-based mulch led to faster nutrient release, with higher increases in nitrogen, phosphorus, and potassium compared to leaf-based mulch. In contrast, the pH of the leaf treatment rose significantly over the 7-week period, while other soil conditions showed only minor changes. These findings suggest that fruit and vegetable waste has the potential to serve as a more effective and accessible alternative to traditional wood chip mulch, improving soil fertility while supporting sustainable resource use. This work contributes to developing more efficient and practical strategies for urban waste management. The volunteers and GSP staff are encouraged to collect the fruit or vegetable wastes from their kitchen, and turn these wastes into the alternatives of wood chips mulch. This action can greatly reduce the wastes as well as the time & effort in processing the wastes. Meanwhile, volunteers and staff can learn the essence of sustainability through collecting the peels in the kitchens.