Effect of Mixing Ratios of Rice Husk Ash and Coco Coir on the Improvement of Green Waste Compost as a Substrate for Cucurbitaceae Seedlings

Abstract

ABSTRACT Green waste is gradually increasing as national forest city construction is promoted. Using green waste compost (GWC) products as seedling substrates is an effective way to achieve ecological sustainability. Nevertheless, some GWC are not always suitable for directly serving as seedling substrates due to their inappropriate physicochemical properties (i.e. undesirable porosity, high pH, high salinity, lower nutrient elements, etc.). This research aimed to evaluate how the addition of rice husk ash (RHA; 0, 2.5, 5%) and coco coir (CC; 0, 10, 20%) affected the physicochemical properties of GWC as well as its usage as a seedling substrate for Cucurbitaceae plants. The GWC was optimized by 2.5% RHA and 10% CC as the seedling substrate had the best physical and chemical properties (i.e. bulk density, porosity, water-holding capacity, pH, conductivity, and nutrient content). And the seedlings of cucumber and watermelon grew best under this seedling substrate in terms of germination energy and total biomass. Compared to GWC without RHA or CC amendments, GWC modified with 2.5% RHA and 10% CC enhanced the germination energy and total biomass of cucumber seedlings by 252% and 60%, respectively, and the germination energy and total biomass of watermelon seedlings increased by 61% and 67%, respectively. In consequence, the GWC that had been modified by 2.5% RHA and 10% CC was an excellent seedling substrate for Cucurbitaceae plants.