Of all the trace elements, this is the one you don’t want to have to ask for by it’s full name. Molybdenum (Mo) is so hard to pronounce that it’s often shortened to ‘moly’. That aside, you do need to make sure you have enough in your pastures.
Mo is needed for normal plant metabolism, but more importantly, it’s needed by the Rhizobium bacteria that fix nitrogen in legumes. In fact, these bacteria need around ten times more Mo than do plants.
Some soil types are more vulnerable to Mo deficiency than others. In the South Island, alluvial soils, yellow-grey earths and yellow-brown earths are at risk. A deficiency is much more likely in soils with a pH of less than 5.8. If you have low clover content and poor-fertility grass species, it’s worth checking for Mo deficiency.
If clover-only herbage samples (best taken in summer) show that Mo is less than 0.1 mg/kg DM and nitrogen is less than 4.5% DM, then clovers are Mo deficient.
Deficiencies can be corrected with an application of granular molybdenum. Only small quantities are required, so check with your rep before doing anything.
To keep pasture Mo within desired levels on soils that are known to be Mo deficient, apply Granular Molybdenum (10% Mo) at 200 g/ha once every four years.
Yes, if the soil pH needs increasing then an application of lime may be sufficient to correct any Mo deficiency. It won’t always be the case, so testing is important.
Excessive Mo (> 1 mg/kg DM) can induce copper deficiencies in stock, so never apply lime and Mo together, never guess how much Mo you need, and never apply more than recommended by your Ballance rep.
