Unlike animals, which can substitute another form of food if a preferred one is unavailable, plants must have all their mineral nutrients available to them. There is almost no possibility of substitution. Thus if one nutrient is in short supply crop growth is inhibited. Read more on the PDA website.

Potash Development Association (PDA) is an independent organisation formed in 1984 to provide technical information and advice in the UK on soil fertility, plant nutrition and fertilizer use with particular emphasis on potash. See also www.pda.org.uk.