Zinc and its Role in Crop Production

Understanding what inhibits the uptake and translocation of zinc will help us to supply this important micronutrient during time of peak demand.

Most people recognise that with many soils across Australia, and the world for that matter, have varying zinc deficiencies.  But the function of zinc, and many trace elements, is an area where it can often be misunderstood.

Seedling. Early growth is when Zinc is required.

Zn may not be available for early growth when it is needed

 

A & L Canada Laboratories, INC. explains this well:

Zn is predominantly taken up as a divalent cation, Zn2+ (two chemical bonds) but in some cases of calcareous and high pH it is believed to be taken up as a monovalent cation ZnOH+(only one chemical bond).  Zn interactions in both plants and soils are quite complex and play a major role in how and when we should apply Zn to a crop.

What Inhibits Zinc uptake in Soil and Plants?

Understanding what inhibits the uptake and translocation of zinc in both soil and plants will also help us to supply this important micronutrient during time of peak demand. High concentration of divalent cations such as Ca2+ will inhibit zinc uptake however the most understood reaction is the Phosphorus to zinc relationship and how it effects Zn availability.

In soils with low zinc, large applications of P will induce even further Zn deficiency.  Ideally people say a 10:1 ratio of P:Zn is ideal in soils.  However, if a soil has high P then trying increase Zn to achieve this type of ratio can cause other issues.

This is also true in the plant itself when high concentrations of P in the shoots will inhibit Zn translocation; which may be more important during seed development.  Again as was in the soil the P:Zn ratio is more important than the actual concentration to predict the availability of Zn to the plant.

Balance and ratio in the soil and plant is key for optimum growth of your crop.  If your soil is high in P then foliar Zn becomes and even more crucial tool for you.  Straight Zn products such as EDTA and Citrate chelated zincs are ideal in these situations. If P and Zn are both low then a zinc phosphate foliar could be the better option. A product such as GroPhoz is ideal in this situation

Temperature of the soil in the spring can have an influence on the amount of Zn that is available from the soil.  Even in soils with adequate zinc levels, zinc may not be available for early growth when it is needed.  The earlier a crop is planted the greater the need for row-applied zinc and foliar options.