Role of Magnesium in Potato Production

Magnesium plays a central role in photosynthesis, as it is present in the center of each chlorophyll molecule. It is also involved in various key steps of sugar and protein production as well as the transport of carbohydrates from the leaves to the tubers.

Magnesium and relative yield

Severe magnesium deficiency can reduce yields by up to 15%. Regular use of magnesium on an annual basis has provided yield increases of 1 to 10% in trials. Adequate magnesium is needed during tuber bulking. If dry soil conditions restrict uptake, then foliar sprays can be very effective.

Magnesium and yield

Trials in UK also show the effect magnesium has on yield.

Magnesium and specific gravity

Low levels of magnesium will reduce the starch content of tubers and protein levels that affect the taste of the cooked potato. Trials in Australia confirm the positive benefits of magnesium on specific gravity.

Magnesium and dry matter

Magnesium also benefits tuber dry matter, as trials in Holland show.

Magnesium and tuber discoloration

Low magnesium levels can increase susceptibility to enzymatic discoloration, as studies in USA show.

General guidelines for magnesium application

Uptake of magnesium is dependent upon the cation exchange capacity of the soil and its balance with the other cations, especially potassium. High concentrations of potassium in the soil can induce magnesium deficiency. In such cases, foliar applications of magnesium are beneficial.

Magnesium at potato growth stages
Planting	Chlorophyll production, growth and enzymatic activity
Tuber initiation	Photosynthesis and enzymatic activity
Bulking	Photosynthesis, carbohydrate transport from the leaves to the tubers, and enzymatic activity