REAP supplemental fertilizer improves greenhouse crop yield

Background Mine tailings contain rare earth elements, including lanthanum and cerium, and plant micronutrients including iron. Previous studies have demonstrated that fertilizers containing rare earth elements and/or micronutrients can influence plant physiology, nutrient uptake and crop yield. However, applying the right dose of these fertilizers is critical since the concentration range associated with benefits is often narrow, and overapplication can lead to crop yield reductions. This study aimed to quantify the effects of a water-soluble fertilizer, REAP, on the yield of greenhouse crops. Methods In the first experiment, the effects of three concentrations of REAP (100, 250 or 500 ppm) were compared to a control (0 ppm REAP) on growth of lettuce, tomato and pepper growing in soilless media. In the second experiments, the effects of REAP applied at higher rates (500, 1000 and 2000 ppm) were compared to a control (0 ppm REAP) on the growth of lettuce, peppers, tomato and cantaloupe. Results In the first experiment, there were no significant differences in yield between treatments, REAP appeared to promote root development. In the second experiment, there were significant yield increases for all crops treated with REAP. Gas exchange rates and nutrient concentration of tomato plants receiving REAP were not significantly different from the control. These results demonstrated that nutrient elements in REAP, including lanthanum, cerium, and micronutrients, improved the growth and yield of vegetable crops when applied at rates ranging from 500 to 2000 ppm.