Magnesium mobility in soils as a challenge for soil and plant analysis, magnesium fertilization and root uptake under adverse growth conditions

Due to its unique chemistry magnesium (Mg) is subject to various cycling processes in agricultural ecosystems. This high mobility of Mg needs to be considered for crop nutrition in sustainable agricultural systems. The Mg mobility in soils and plants and its consequences for crop nutrition are understood, but recent findings in crop Mg uptake, translocation and physiology particularly under adverse growth conditions give new insights into the importance of Mg in crop production. The aim of this review is to combine the knowledge on the origin and mobility of Mg in soils with the role of Mg in plant stress physiology and recent evidence on the principles of crop Mg uptake. The question is addressed whether the progress made in Mg research, particularly on the role of Mg in stress physiology, makes a revision of the development of Mg fertilization recommendations necessary. New insights into Mg uptake and utilization but particularly into the role of Mg in increasing crop tolerance to various stresses indicate changes in the crop Mg demand under adverse growth conditions. Future work should incorporate these findings in optimization of site-specific balanced fertilization programs particularly under stress conditions.