Molybdenum

Constraint – Molybdenum 

Plant use

• Molybdenum is the least available micronutrient

• Molybdenum forms an essential element in nitrogen fixing enzymes, as well as being directly involved in nitrogen metabolism and the electron transfer system

Symptoms 

• Stunted pale plants

•  More common on acidic sandy soils

• Tissue between veins of older leaves becomes paler green with scattered white dead spots that expand as deficiency worsens

• Leaf margins are frequently brown and "scorched"

• Limited response to nitrogen fertiliser

Damage

• Yield penalty is generally not significant

Management

There is no relaible soil test for molybdenum. Maintenance of soil pH above 5.5 will act to increase the available molybdenum in the soil, as well as application of 50-60 g Mo/ha every 5-7 years on responsive soils. A foliar spray can be effective for the current season, as can a seed treatment. 

Links and Resources

AOF - Canola nutrition. Molybdenum Page 6 of 8. Very brief statement on Molybdenum management.

DAFWA - Diagnosing Molybdenum deficiency Introduction, what to look for in paddock and plant, what else it could be, where does it occur, management strategies, and monitoring. Page last updated 2014.

DEPI VIC - What nutrients do plants require? Molybdenum Section 6.4.1. Molybdenum as an essential trace element, deficiency symptoms, soils most at risk, animal health implications, and management. Page last updated 2013.

GRDC - Best Practice Management Guide. Molybdenum Page 37 of 92. Information on molybdenum deficiency, plant use, and fertiliser requirements. Published 2009.

GRDC - Micronutrients and trace elements. Molybdenum 4 page PDF. Key points, general introduction, crop demand and uptake, tissue testing, soil testing, visual symptoms, soilmapp, effects of soil type, and treatment. Published 2013.

IPNI - Canola 4R Guide. Molybdenum Page 20 of 21. Molybdenum deficiency, description, impact, contributing factors, and management. Published 2013.