Abstract
Annually, a large volume of sprout growing media is wasted following use, which can result in serious environmental pollution at sprout production areas as well as resource wastage. Sprout growing media are often made from difficult to biodegrade lignocellulose-rich materials; however, they also have high organic matter (OM) content and rich nutrients, making them reusable in many applications. Therefore, taking full advantage of spent sprout growing media (SSGM) and combining it with other agricultural by-products could produce organic fertiliser and environmentally-friendly solution with high economic efficiency. The present study involved 4 experimental formulas for thermophilic composting (1 control formula with 100 % SSGM and three mixed formulas with 60 % SSGM and 40 % different by-products such as straw, cow dung and soybean residue). During the composting process, the physicochemical properties changes of composting heaps were determined. The temperature of compost heaps reached their maximum after 3 d (45 - 72 (C), then gradually reduced to the value equal to the environmental temperature at the end of composting. Moisture content, pH, organic matter and C: N ratio ranged between 57.57 - 69.23 %, 5.16 - 6.96, 29.72 - 82.37 % and 12.06: 1 - 30: 1, respectively. After 63 d of composting, the nutrient content of composts increased with the highest value of total nitrogen (1.46 %) and potassium (4.24 %) using formula CT2, highest total phosphorus using formula CT4 (1.5 %), and highest OM using formula CT4 (55.44 %). The heavy metal content (Cu, Zn, Pb, Cd, As) of all compost products was under permitted standards, and they were not contaminated with pathogenic bacteria (Salmonella spp., E. coli). The evaluation of compost maturity based on using seed germination and root growth testing indicated that compost products were mature. The results of this study indicate that the treatment of SSGM according to formula CT2 is most suitable for producing high-quality compost and solving the problem of waste causing environmental pollution in sprout production areas.
