Van Rooyen, Ignatius LeopoldusNicol, Willie2022-11-112021-06Van Rooyen, I.L. & Nicol, W. 2021, 'Optimal hydroponic growth of Brassica oleracea at low nitrogen concentrations using a novel pH-based control strategy', Science of The Total Environment, vol. 775, art. 145875, pp. 1-9, doi : 10.1016/j.scitotenv.2021.145875.0048-9697 (print)1879-1026 (online)10.1016/j.scitotenv.2021.145875https://repository.up.ac.za/handle/2263/88272Please read abstract in the article.en© 2021 Elsevier B.V. All rights reserved. Notice : this is the author’s version of a work that was accepted for publication in Science of the Total Environment. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. A definitive version was subsequently published in Science of the Total Environment, vol. 775, art. 145875, pp. 1-9, doi : 10.1016/j.scitotenv.2021.145875.Proton to nitrate ratioNitrate concentration controlNitrogen spillageSoilless agriculturePostprint Article