The response of potatoes to magnesium under various soil conditions

Summary

• 1. A nutritional disease in potatoes was found to be due to a deficiency of magnesium.

• 2. The magnesium deficiency was found to be more severe on acid soils and under conditions where commercial fertilizers had been used in large amounts for a number of years.

• 3. Supplying magnesium to various phosphorus carriers, under acidsoil conditions, was effective in increasing the yields of potatoes very markedly.

• 4. In one cooperative field experiment yield increases of approximately 100 bushels per acre were obtained through the use of magnesium.

• 5. All forms of magnesium, used in these experiments, were found to be equally effective when supplying at least 25 pounds of MgO per acre.

• 6. Under acid-soil conditions it is recommended that magnesium limestone supplying 25 to 35 pounds of magnesium oxide per acre be mixed in the fertilizer or an occasional top-dressing of magnesium limestone be made.