Rosemary growth and nutrient balance: Leachate fertigation with leachates versus conventional fertigation

The free discharge of drainage water from greenhouse horticultural production to the environment is a current environmental concern due to its capacity to contribute to environmental pollution. This has led to the search of sustainable alternatives for its reuse in the production of other crops. However, before the large-scale use of such horticultural leachates in ornamental plants, the effects of such fertigation treatments on ornamental plants need to be evaluated. Plants of rosemary were grown in pots with a mixture of sphagnum peatmoss and Perlite and subjected to three fertigation treatments: T0 (a standard nutrient solution or control), T1 (raw leachates from Cucumis melo) and T2 (a mixture of raw leachates from C. melo and tap water 1:1 v/v, over a period of 9 weeks. At the end of the experiment, the growth parameters, color of leaves as well as water and nutrient uptake efficiencies and their losses were assessed for each fertigation treatment. The total dry weight and the water use efficiency of rosemary plants decreased under the fertigation with raw and diluted leachates. In addition, rosemary plants were shorter compared to the control but there were no differences in leaf color between the fertigation treatments. The uptake of N, P and K were affected by the applied fertigation treatments in a different manner. The use of horticultural leachates in the production of ornamental plants (as shown here for melon and rosemary) is feasible and presents a viable option to reduce water and nutrient input in plant production.