Feasibility of Plug Production Utilizing Digestate from Home-Waste to Energy Systems (H-WEF)

Abstract

The integration of sustainable technologies in waste management systems has become imperative in addressing the escalating challenges of agricultural productivity and sustainability. Plugs are essential when starting crop production in controlled environment agriculture (CEA) setups and greenhouses. Horticultural crops such as vegetables, fruiting, and ornamental plants that utilize plugs have demonstrated higher success rates, healthier plants, and higher total yields. The APS Laboratory for Sustainable Agriculture explored the innovative utilization of digestate from the Home Water-Energy-Food Systems (H-WEF). The H-WEF system converts household food waste into biogas, electricity, and nutrient-rich digestate. The digestate from the H-WEF system was used to produce agricultural plugs, presenting a novel approach to circular resource utilization. We carried out the growth of Rex Butterhead Lettuce Latuca sativa plugs with 1) control system (synthetic fertilizer) and seven different treatments, 2) 5% Digestate—95% RO Water (5D–95RO); 3) 10% Digestate—90% RO Water (10D–90RO); 4) 15% Digestate—85% RO Water (15D–85RO); 5) 20% Digestate—80% RO Water (20D–80RO); 6) 25% Digestate—75% RO Water (25D–75RO); 7) 30% Digestate—70% RO Water (30D–70RO); 8) 35% Digestate—65% RO Water (35D–65RO). The plugs were cultivated for 15 days in a controlled environment until two leaves had developed after the cotyledon. After 15 days, we collected data on wet weight (g), plug head area (cm 2 ), total leaf area (cm 2 ), total chlorophyll content (mg/cm 2 ), and dry weight (g). In addition, we collected data on the Leaf Area Index (LAI, cm 2 /cm 2 ) and Specific Leaf Area (SLA, cm 2 /g). The synthetic fertigation yielded a higher wet weight than the following treatments: 5D–95RO, 10D–90RO, and 35D–65RO. While the 30D–70RO treatment produced a larger plug head than all other treatments. The digestate-based fertilizers were comparable to the synthetic fertilizer at dilutions of 25D–75RO and 30D–70RO. This study underscores the viability of using digestate for plug production, providing crucial insights for growers navigating the challenges of sustainable agricultural practices.