Enhancing water use efficiency (WUE) and yield in Lactuca sativa: a comparative study of simplified soilless cultivation (SSC) versus traditional soil-based systems in Colombia

Simplified soilless cultivation systems (SSC) have emerged as a viable solution for sustainable fresh food production, particularly in response to the challenges posed by changing climatic conditions and the global population expansion. The increasing pressure on land and water resources intensifies the need for innovative approaches, especially in regions struggling with unpredictable rainfall patterns, limited arable soil, as well as issues related to low-quality water and food scarcity. This study conducted in Popayan in the Cauca region of southern Colombia, aimed at evaluating the productivity and water use efficiency (WUE) of lettuce (Lactuca sativa L.) in either a closed-loop simplified soilless system or a traditional soil-based cultivation. The “Garrafas PET” soilless system, constructed from bamboo poles and plastic bottles, served as the experimental platform, incorporating various growing substrates such as coconut fiber, peat, carbonized rice husk, and a mixture of the three. The adoption of the SSC system significantly enhanced WUE, especially when using peat (71.2 g L-1), rice husk (alone or in a combination with peat and coconut fiber, average of 51.1 g L -1), or coconut fiber alone (28.5 g L -1) as compared to traditional on-soil cultivation (3.74 g L -1). Yield differences were observed between the cultivation techniques. The SSC with peat exhibited highest yields (3.9 kg m -2), similarly to soil-based cultivation (3.2 kg m -2), which on the other end equaled productivity achieved in the SSC with the adoption of rice-hulls substrates (alone or in combination with coconut and peat, 2.8 kg m -2 on average), while coconut fiber alone scored the lowest production (1.6 kg m -2). This research underscores the potential of SSC in mitigating resource challenges and advancing sustainable food production systems.