Soil testing is an important activity for a successful garden. Soil stewardship is an ongoing process, where you test and amend, grow some stuff, then test, amend and grow some stuff….and so on. Focus on building soil tilth so it can really hold and make available to the plants all the important nutrients. You do this in part by adding compost, manure, rock dust, bone meal, kelp & fish emulsions. Read this article series to learn more about each of the 13 key nutrients for your garden.

 
 

Molybdenum is required by the plant for carrying out “redox reactions” in enzymes that include nitrate reductase to convert nitrates into amino acids. Redox reactions are necessary to processes involving nitrogen metabolism as well as synthesizing phytohormones. Molybdenum is also crucial for the symbiotic nitrogen-fixing bacteria that is found in legumes, and is necessary in order to convert inorganic phosphorous into organic forms within the plant. Without Molybdenum, plants could not utilize phosphorous or nitrogen.

If the leaves show curled mottled edges the plant may have a deficiency of molybdenum.

To correct a deficiency of Molybdenum
  • add lime or wood ash, which will be most effective in acidic soils or soils that get leached by a lot of rain
  • young plants can be sprayed with a 5% solution of sodium molybdate (a salt)

Like any salt, if Molybdenum builds up in the soil it will also accumulate within the plant and cause damage such as the edges of the leaves looking scorched and leaves falling off the plant. Eating a lot of plant material with a high Molybdenum concentration can lead to a condition called Molybdenosis in livestock.

To offset excessive Molybdenum
  • Adding sulfur to the soil can help decrease the plant’s Molybdenum uptake
    NOTE: Elemental sulfur is an accepted organic additive, however, Ontario Canada farms receive yearly 8- 13 kg/ha (7- 12 pounds/acre) of sulfur deposited by rainfall so this should be included in considering how much to apply