Experimental and life cycle assessments of tomato (Solanum lycopersicum) cultivation under controlled environment agriculture

Abstract

Crop production system assessments can evaluate if controlled environment agriculture is feasible as compared with semi-controlled and/or uncontrolled conditions. This study assessed the growth of tomatoes (Solanum lycopersicum) in three different environmental conditions (a fully controlled greenhouse mimicking controlled environment agriculture, a semi-controlled nethouse, and an uncontrolled open space) and three nutrient applications including nutrients supplied with i) 100 % inorganic fertilizer, ii) 100 % compost, and a mixture of 50 % of i and ii to be termed as mixed fertilizer from here onward. A life cycle assessment of tomato production in the greenhouse, nethouse, and open space cultivation phases was carried out using experimental data. A life cycle directory, a holistic cradle-to-gate concept, OpenLCA software, and commercial databases were used to evaluate the experimental activities’ potential for acidification, eutrophication, global warming, human toxicity, ozone depletion, and photochemical ozone creation. The environmental conditions and nutrient applications had individual and interactive effects on plant growth variables, fruit yield, and water use efficiency. For example, under the individual effects, the fruit yield means of greenhouse (9.52 ± 2.88 Mg/ha), nethouse (14.4 ± 3.64 Mg/ha), and open space (10.9 ± 1.88 Mg/ha) were significantly (P ≤ 0.05) different from one another. Fruit yield for the mixed fertilizer treatment (14.7 ± 3.06 Mg/ha) was 22.3 % and 41.9 % higher than those of inorganic fertilizer (11.5 ± 1.86 Mg/ha) and compost (8.55 ± 2.15 Mg/ha) treatments alone. The life cycle analysis showed that the phases of the nursery and product transportation (in all 3 cultivation phases) and irrigation systems in the nethouse and open space phases were the hotspots for their environmental impact. Replacement of irrigation pumps run on government electricity is suggested with solar-powered ones for nethouse and open space. Despite lower tomato yield, a fully controlled greenhouse was considered environmentally safe and the most efficient controlled environment agriculture system (with a proper supplemental lighting system) as it can operate year-round to produce an optimum annual yield of horticultural crops in arid and humid environments of the Arabian Peninsula. The significance of this study includes i) the production of Qatar-specific experimental data that is scarce in the literature, ii) the findings that insufficient supplemental lights could lower tomato yield from a greenhouse compared to a nethouse, iii) the life cycle-based environmental burdens of crop production systems, and iv) discoveries that, for arid regions, the nethouse cultivation could serve as economically viable, energy-efficient and environment-friendly tomato production systems.