Trace elements revisited
Jim Shovelton, Meridian Agriculture
Trace element requirements of pastures are often overlooked.
The discovery of the need for trace elements in Australia revolutionised pasture production in the 1950s. However, deficiencies are still widespread. Clover samples analysed by Nutrient Advantage over the last 5 years showed about 50% were deficient in molybdenum.
The photo shows a test strip site in the upper Murray which had been receiving annual applications of single superphosphate for around 40 years, most of which were ineffective because of the molybdenum deficiency.
Often trace elements are not added because of the perception of cost.
The cost of adding molybdenum to superphosphate is currently $35/t. At an application rate of 50 gm/ha this is cost of about $9/ha. Molybdenum reapplication periods vary, but assuming reapplication is required every 5 years, the annualised cost is $1.80/ha. If pasture dry matter was valued at $200/t, a response of only 9 kg dry matter/ha/yr would be required to cover the extra cost of the molybdenum.
Molybdenum is not the only trace element missing in parts of Victoria. Others include boron, copper, cobalt, selenium, iodine and zinc.
Fertiliser test strips showing clover response to molybdenum
The understanding of the role of trace elements in Victorian grazing systems was summarised in the 1986 Agriculture Victoria publication ‘Trace Elements for Pastures and Animals in Victoria’. Since that time there have been changes in farming practices, such as liming, which will have affected trace element availability. The information needs updating to confirm the extent and distribution of trace element deficiencies in Victoria and update diagnostic, treatment and management recommendations.
MLA have funded a program to improve and update our knowledge of trace element requirements in Victorian pastures. The project is looking for involvement by producers. A key activity will be the opportunity for producers to establish simple test strips on their farm to look for responses. Through the support of group co-ordinators or agronomists, these strips will be assessed for changes in growth and pasture composition and sampled for herbage analysis. Test kits will be distributed through grower networks such as Bestwool/Bestlamb and BetterBeef. Other groups or networks will also be encouraged to participate.
Regional workshops for producers and service providers will be held during the duration of the project. The Trace Element Book will be updated and made available for farm advisers, agronomists and farmers. The project will be managed by Meridian Agriculture in conjunction with Agriculture Victoria and the Mackinnon Project.
Further information contact: Jim Shovelton, Meridian Agriculture
Email: traceelements@meridian-ag.com.au