The present invention relates to the use of a composition comprising at least one basic L-amino acid as a dual effect growth additive, which dual effect comprises at least one growth-enhancing element and at least one water use efficiency (WUE) increasing element.The invention also relates to a method of manufacturing a composition, which method comprises preparing at least one basic L-amino acid into a liquid or solid fertilizer composition, optionally by mixture with further plant nutrients and/or other materials such as solvents, to produce a dual effect growth additive wherein the additive so produced comprises growth-enhancing element(s) as well as water use efficiency (WUE)-increasing element(s), and wherein no nitrate or nitrate-containing compounds are added or formed during the manufacture thereof.
