Productive Pastures Oct 2013 V1 | Page 10

Micronutrients and your pastures Plants require micronutrients in very small amounts compared with nitrogen, phosphorus, potassium and sulphur. Molybdenum However, the micronutrients can be just as important, because a plant’s production is limited by the nutrient in shortest supply to its requirements. Molybdenum is particularly important for legume growth. Pastures grown on acidic soils in higher rainfall areas tend to need more applied molybdenum. Copper, zinc, boron and molybdenum are all critical to pasture growth. A deficiency in molybdenum in legume pastures will show up as stunted growth and rhizobium nodules will be pale and colourless, rather than a healthy pink colour. Micronutrient deficiencies may also affect animal health. Soils usually only have trace levels of these nutrients which makes them difficult to quantify accurately in soil testing. Leaf tissue testing is the best way to assess micronutrient status. In non-legume plant species, a deficiency in molybdenum blocks the nitrate conversion to amino acids, so visual symptoms will appear similar to a nitrogen deficient crop. Excess molybdenum in the plants does not affect plant growth, but it can impact on animal health. Plants high in molybdenum (or low in molybdenum and high in sulphur) can induce copper deficiencies in livestock. An application of 50 to 100 g/ha of molybdenum every five years is generally adequate, except in rainfall zones higher than 1,000 mm/year or on high phosphorus fixing soils. Molybdenum can be applied with SuPerfect. Copper Because copper is an important animal nutrient, deficien ???)??????????????????????????????????????????????)Q??????????????????????????????????????????)????????????????????????)]????????????????????????????????????????????????)?????????????????????????????????????????????????)?????????????????????????) ????????????????????????????????????????????)?????????????????????????????????????????) ???????????????????????????????????????????????)??????????????????????????) ??????????????????????????????????????????????M?A?????((??((0