Grocery Waste Compost as an Alternative Hydroponic Growing Medium

Abstract

Modern hydroponic substrates have contributed significantly to the popularity and progress of hydroponic cultivations worldwide, nevertheless, their development, transportation, and disposal often come at a significant environmental cost. Here we investigate the feasibility of partial to total replacement of conventional organic growing media constituents, such as cocodust (C), in a 20% perlite (P) and 80% cocodust substrate (hereafter control 8C), with compost from locally sourced grocery waste (W). For this purpose, four treatment mixtures were developed (6C:2W, 4C:4W, 2C:6W, 8W), with the grocery waste-compost fraction ranging from 20 to 80%, respectively (perlite constant at 20%). The new substrates were tested on hydroponic lettuce (Lactuca sativa var. Tanius) cultivation. During the 35-day experiment, lettuce physiology was evaluated using chlorophyll concentration [SPAD], chlorophyll fluorescence [Fv/Fm], number of leaves, and plant growth index. At harvest, the plant yield was evaluated using leaf area [cm2], leaf fresh and dry weight [g], as well as leaf firmness [g]. Results show that substrates with compost led to superior physiology and yield characteristics, with 8W inducing a significant increase in leaf area, chlorophyll concentration, dry weight, and firmness, by 11.6%, 5.4%, 19.8% and 12.8%, respectively, compared to the control treatment 8C. Results indicate that grocery waste-based compost is an excellent sustainable alternative for the soilless cultivation of lettuce. After its use in hydroponic cultivation, substrate material is safe to dispose of or be used as a soil amendment, thus contributing to a circular agro-food economy model.

Effect of Compost from Cardoon Biomass, as Partial Replacement of Peat, on the Production and Quality of Baby Leaf Lettuce

“…Similar to our results, Moschou et al [70] found that in hydroponic lettuce (Lactuca sativa var. Tanius) cultivation waste-based compost (from fruits, and vegetable and olive pruning) substrate significantly increased leaf dry weight (19.8%) of the plants compared to the conventional organic growing media constituents (cocodust).…”

Growth Analysis of Lettuce (Lactuca Sativa L.) Using Nutrient Film Technique (NFT) in Hydroponic Systems

“…A porous medium has adequate pore space to allow water and air to move more flexibly. It reported that planting medium with high porosity could increase the mung bean's lateral root length and shoot its dry weight (Kusuma et al, 2013;Moschou et al, 2022;Thalib, 2019). Increasing soil porosity can increase plant growth (Anastasia et al, 2014).…”

Water Availability in Pumice, Coir, and Perlite Substrates Regulates Grapevine Growth and Grape Physicochemical Characteristics in Soilless Cultivation of Sugraone and Prime Cultivars (Vitis vinifera L.)

“…The results can be partially attributed to the increased water availability of perlite:coir and perlite compared to pumice, but mainly to the significantly increased organic nitrogen (%) concentration of the leaves in perlite:coir and perlite compared to pumice and sole coir. Correspondingly, Moschou et al [82] investigated the effect of grocery waste compost on the growth parameters of lettuce plants, and according to the results, grocery waste-based compost led to a significant increase in leaf area (cm 2 ) compared to perlite and coir substrate.…”