Soil–plant interactions, which have been studied for well over a century (Hinsinger and Marschner 2006), represent one of the most exciting challenges of scientific endeavours of the present century. These studies cover a wide range of topics, from chemistry to molecular biology, and from rhizosphere to ecosystems. Soil–plant interactions have been the focus of agriculture-oriented studies worldwide for many years; however, in the last decade, much attention has been shifted towards issues related to global change, such as greenhouse gas emission from soil–plant systems, and soil carbon management. This trend is evidenced by the fact that among the 100 papers involving ‘‘soils’’ listed as highly cited papers, about 60% are related to soil biology, soil carbon in particular (Web of Science http://portal. isiknowledge.com/portal.cgi?DestApp=WOS& Func=Frame). Highly cited review papers (all citation classics, i.e. all cited over a hundred times) published in Plant and Soil include Haynes (1982) on effects of liming on phosphorus availability, Gorham et al. (1985) discussing salt tolerance, Melillo et al. (1989) dealing with carbon and nitrogen dynamics in soil, Graham et al. (1992) reviewing zinc efficiency in cereals, Lynch and Whipps (1990), and Jones (1998), both dealing with carbon flow in the rhizosphere, and Marschner and Dell (1994), on nutrient uptake in mycorrhizal symbioses. The review papers on plant adaptations to acid soils (Marschner 1991) and aluminium (Kinraide 1991), plant strategies for iron acquisition (Marschner and Romheld 1994), responses of soil biota to elevated atmospheric CO2 levels (O’Neill et al. 1987, 1994), symbiotic nitrogen fixation (Mariotti et al. 1981; Peoples et al. 1995), soil microbial diversity and sustainability (Kennedy and Smith 1995), nitrogen emissions from agricultural soils (Mosier et al. 1996), and on effects and of adaptation of anoxia (Drew 1983) have equally appealed to a very large number of readers for prolonged periods. The authoritative review by Vogt et al. (1996) on root dynamics in forest ecosystems as dependent on climate and forest type also continues to be cited. These reviews show the breadth of Plant and Soil as well as the enormous appreciation for the reviews that have been published in the journal over many years. That is why we have decided to start a new series of regular, authoritative reviews: our Marschner reviews. These review papers are by invitation only, as further explained below. Our citation classics are by no means restricted to review papers. Wijler and Delwiche (1954) published our very first citation classic, reporting on denitrifying H. Lambers (&) L. Bultynck University of Western Australia, Crawley, Australia e-mail: hlambers@plants.uwa.edu.au