Comparison of Land, Water, and Energy Requirements of Lettuce Grown Using Hydroponic vs. Conventional Agricultural Methods

Abstract

The land, water, and energy requirements of hydroponics were compared to those of conventional agriculture by example of lettuce production in Yuma, Arizona, USA. Data were obtained from crop budgets and governmental agricultural statistics, and contrasted with theoretical data for hydroponic lettuce production derived by using engineering equations populated with literature values. Yields of lettuce per greenhouse unit (815 m2) of 41 ± 6.1 kg/m2/y had water and energy demands of 20 ± 3.8 L/kg/y and 90,000 ± 11,000 kJ/kg/y (±standard deviation), respectively. In comparison, conventional production yielded 3.9 ± 0.21 kg/m2/y of produce, with water and energy demands of 250 ± 25 L/kg/y and 1100 ± 75 kJ/kg/y, respectively. Hydroponics offered 11 ± 1.7 times higher yields but required 82 ± 11 times more energy compared to conventionally produced lettuce. To the authors’ knowledge, this is the first quantitative comparison of conventional and hydroponic produce production by example of lettuce grown in the southwestern United States. It identified energy availability as a major factor in assessing the sustainability of hydroponics, and it points to water-scarce settings offering an abundance of renewable energy (e.g., from solar, geothermal, or wind power) as particularly attractive regions for hydroponic agriculture.

Automatically controlled deficit irrigation of lettuce in “organic potponics”

“…Commercial lettuce production spends about 250 L kg −1 of water demands (Barbosa et al, 2015). Here, it was used only 30.45 L kg −1 , which is close to other studies conducted under precise control of irrigation conditions (Montesano et al, 2016).…”

Efficiency and effectiveness of vitamin C-substrate organo-mineral straight fertilizer in lettuce (Lactuca sativa L.)

“…In prehistoric times, humans formed clans and started cultivating plants as a food supply. Conventional agricultural systems can cause multifarious negative impacts on the environment such as inefficient use of water, large-scale land requirements, outflow of residual pesticides, and erosion with soil degeneration [1]. Therefore, over time, people have attempted to develop cultivation techniques for more efficient food production and environmental conservation.…”

Composted slaughterhouse sludge as a substitute for chemical fertilizers in the cultures of lettuce (Lactuca sativa L.) and radish (Raphanus sativus L.)

“…As observed in this study, LDW was not altered at the same doses of the composts. Lettuce plants are demanding in irrigation and water use of 250 L/Kg (FW)/year is estimated for plants in order to achieve proper development (Barbosa et al, 2015).…”