Sodium in Fertilizers

Application of sodium to many crops has been reported to stimulate growth, particularly when potassium is deficient (15,101–107). This phenomenon has been documented repeatedly with Beta species (red beet, fodder beet, and sugar beet) (108–126), and in a range of other crops including asparagus (Asparagus officinalis L.), Italian ryegrass (Lolium multiflorum Lam.), tomato (Lycopersicon esculentum Mill.), potato (Solanum tuberosum L.), carrots (Daucus carota L.), celery (Apium graveolens L.), and flax (Linum usitatissimum L.) (15,74,101,103,104,107,127,128). There is particular interest in sodium fertilizer application to forage crops, since animals require substantial amounts of sodium (129,130). Lactating dairy cows need a concentration of about 2 g Na kg^-1 in forage (131). The problem is particularly evident on soils that are intensively managed and deficient in nutrients (132–134), although there are exceptions (135). Application of sodium fertilizer improves the quality of fodder crops and makes them more acceptable to animals (136–140).