Author

Jess Sampson

Jess Sampson

Jess has 11 years of practical on farm agronomic consultancy experience as well as a university level academic agronomic education. Her specialisations in pasture agronomy, seed and trial management means she is well versed in new seed varieties right through to on farm practical solutions to address crop pressures. Whilst Jess is not on farm or at work, she is hanging out with her teenage Sons, fishing, preserving foods or baking!


Jun 24, 2022

by Jess Sampson

Zinc deficiency in Australia is one of the most common micronutrient deficiencies in crops. Zinc deficiencies can occur on a wide range of soils, from heavy alkaline clay soils to light sandy acidic soils.  In crops, zinc is vital for the formation of chlorophyll and carbohydrates. It plays an important role in the movement of water in plants, aiding in root development and starch formation. Zinc is also essential in aiding the production of growth hormones such as Auxins.  The total amount of zinc in your soil can be directly related to the parent material, for example,  basalt soils can contain high levels of zinc, whereas sandy soils can be low in zinc. Although zinc in organic matter is fairly immobile and very little is leached from the soil, it is often not in a readily available form in the soil. There are many factors that can play a key role in the availability of zinc for plant uptake, such as: Organic matter - Zinc can interact with soil organic matter by forming both insoluble and soluble zinc complexes. It can be mineralised and made available to plants from decomposing organic matter.  The amount of chelating agents in the soil have a direct impact on the movement of Zinc. Chelating agents increase the solubility of zinc from the soil and aid its movement through to the roots of the plants. Climatic conditions can also play a role in zinc availability. A wet winter-spring season, like the one we are experiencing in Australia, can result in zinc deficiency in plants, this is a result of reduced microbiological activity. Microbiological activity is important to assist in releasing zinc from organic matter. Because of this waterlogging can tend to increase zinc deficiency. High levels of available iron can adversely affect the plants ability to take up zinc.  The incorrect application of phosphorus fertiliser may induce zinc deficiency, by affecting the physiological availability of zinc in plant tissues. It has been found that Vesicular arbuscular mycorrhiza (VAM) colonisation of plant roots is reduced in crops growing in soils high in phosphorus. That is why it is really important to know your soils and apply the correct fertiliser types and rates.  High water tables or soil compaction can affect plant root development. This can directly affect the dispersion of zinc in the soil, leading to zinc deficiency. VAM is a beneficial fungi which infects the roots of most crops (except canola). The mycelium (fungal threads) assist the plants ability to uptake immobile nutrients such as phosphorus and zinc, It does this by increasing the root surface area. VAM relies on plants for survival. Fallowing land for a long period, e.g. 12 months, or growing non-host crops (canola), can cause populations to decline, thus increasing the risk of zinc deficiency.  Some symptoms of zinc deficiency are: Brown or yellow patches on the new growth Patchy appearance of the crop Brown necrotic spots on the leaves Poor seed set – young tillers may die before setting seed Poor yield/low protein Zinc toxicity is uncommon, and is more likely to occur in acid soils. High levels of zinc can inhibit a plant's ability to uptake P and Fe.  Zinc as a foliar spray should be applied in small amounts, more regularly. Early in the morning or early evening to reduce evaporation and maximise the intake of zinc into the plant. Best results occur when applied before symptoms of deficiency are noticeable.  is a fully chelated form of zinc, making it both more efficient and effective to use. It mixes well with a wide range of liquid fertilisers, humates and chemicals. Cereals 0.5 - 2.5 3-5 leaf stage 50-100 Canola 0.5 - 2.5 4-9 True leaves 50-100 Legumes 0.5 - 2.5 10-14 days before flowering, sooner if a deficiency is known. 50-100 Pasture 0.5 - 2.5 Good leaf cover 50-100 Cotton 1 - 2.5 Prior to flowering 50-100 Grapevines 1 - 3 Flower bud visible & flower bud separated. 200-1000 Citrus 2 - 4 Spring, Summer, Autumn flush 500-1000 2 - 5 Soil application Sources: GRDC.com.au https://www.sciencedirect.com/topics/earth-and-planetary-sciences/vesicular-arbuscular-mycorrhiza Impact Fertilisers Trace elements 1999


Jun 02, 2022

by Jess Sampson

With La Niña in full swing in Australia for the second year, the 2022 season has seen an incredible amount of rainfall across Australia. In April alone, our rainfall was 27% above average as a whole, putting much of Australia into the 10th decile for rainfall.  In a wet season it is really important to keep an eye on our crops' nutrition program. Many of the micronutrients our crops require can be easily leached in wet years. This can result in stunted crops, lower yields or lower protein and oil percentages in crops.  Over the coming weeks we will have a look at these micronutrients, their roles within the plant, and the benefits of proactive application. Boron  Boron is a micronutrient that plants require for healthy cell wall production, it plays an important part in healthy pollination & fruit/seed development. Boron is also instrumental in the translocation of sugars and carbohydrates within the plant.  Along with other micronutrients such as zinc, copper and manganese, it is important to be proactive when applying Boron. Unfortunately, once a deficiency is noticeable, yield has already been affected. For best results it is recommended to apply a small amount, often.  Some indications of Boron deficiency in crops include: Yellowing and death of growing points (Chlorosis) Thickening and cracking of stems (Distortion) Root development anomalies Dropping of buds Discoloration and the crinkling of leaves. As Boron is stored in soil organic matter, its availability will fluctuate according to microbial activity. Boron becomes available as organic matter decomposes. As a result, it can be easily leached, particularly during a wet season.  Calcium, potassium, and nitrogen concentrations in both the soil and plant can affect boron availability and plant function, the calcium:boron (Ca:B) ratio relationship being the most important. Therefore, soils high in calcium will require more boron than soils low in calcium.  As Boron requirements are low it is best to check your crop requirements. Doing a soil test or tissue test is the best way to find out how much Boron is readily available. Higher rates of Boron may be required in heavy clay soils, or soils that have a higher water pH/calcium content.  Boron toxicity is a greater risk on low calcium-content soils. Some symptoms of Boron Toxicity may include: Leaf tip yellowing Leaf necrosis and drop - beginning in the leaf tip Brown & stunted root tips It is best to apply foliar B either in the early morning or evening, when the evaporation rate is low. This will maximise the length of time that the leaves will remain damp, allowing the plant to absorb the most Boron.  is compatible with a wide range of agricultural herbicides and pesticides. Check the Compatibility Guide as a reference. Always do a small jar test before preparing a full tank mix. Cereal 1 - 2 Mid - late tillering 50 - 80 Legu mes 1 - 2 10 - 14 days before flowering 50 - 80 Canola 1 - 2.5 Prior to flowering 50 - 80 Citrus 1 - 2 Spring flush  500-1000 Grapes 0.5 - 2 Flower clusters visible 200 - 800 Pasture 1 - 2 10 - 14 days before flowering 50 - 80 Lucerne 1 - 2 10 - 14 days before flowering 50 - 80 Source