Competition in plants and Induced deficiencies

In plant, when the noticeable symptoms are the direct outcome of a nutrient deficiency, the actual process required for correction are then relatively straight-forward. However symptoms are often the result of interactions with other environmental factors limiting the availability of the nutrient whose symptoms are expressed. The important instance is that of iron deficiency induced by an excess of heavy metals in the environment.

Moving elements like Cu, Zn Cr and Ni compete with Fe and with one another for plant uptake. Competition for uptake is not specific to Fe and heavy metals but is true for all mineral nutrients that are chemically similar and have similar uptake mechanisms. For instance, if the presence of Cu or Zn is relatively less than that of Fe, then excessive concentrations of some other metal such as Ni or Cr will induce a deficiency of one of these nutrients rather than Fe. In the place of the macronutrients, excessive amounts of Mg will compete with K for uptake and can induce a K deficiency in plant. The non-productiveness of serpentine soils is the possible outcome of such competition, with the high Mg of these soils inducing a Ca deficiency.

In the cultivation of plant, the toxicity of a low pH soil is another non exceptional example of a basic nutrient deficiency. Low pH has a two-fold effect on soil nutrients: It enhances the leaching of cations, reducing their availability in the soil, and the relatively abundant protons in the soil which then compete with Ca and other cations for uptake. Nutrient deficiencies can be induced by a number of different mechanisms often working in line to limit the availability of the nutrient present in the soil.