Foliar nutrient sprays are a very effective tool that broadacre farmers can utilize to enhance grain yield and quality. Trace elements such as zinc, manganese and copper are deficient in many cropping regions, but can be easily and cost effectively corrected using foliar sprays. Numerous independent scientific trials with SJB zinc & manganese chelates have shown 10-40% increases in grain yield on deficient soils & 5-10% increases on soils with adequate trace element levels where crops are showing no visual signs of deficiency. At a cost as little as $4/ha for a zinc spray, even a 1% increase in yield would return a profit to the grower on his investment.

In cereal & legume crops, zinc, copper & manganese (see LIG-MALLEE, LIG-PENINSULA) are common issues, particularly in the high pH & calcareous soil types found in South Australia and the Victorian Mallee. The simple reason for this is that in alkaline soil conditions these trace elements are precipitated (chemically bound) so their solubility and availability to the crop are significantly reduced. All these micro-nutrients play important roles in hormone and sugar production which has a significant impact on reproduction (seed set) while copper deficiency can also lead to lodging and subsequent yield loss.

Another benefit of these nutrients is they promote anti-oxidant production that increases the crop’s natural protection against disease and pest attack. In many cases this can reduce or even eliminate the need for in-crop fungicide & insecticide sprays. Early timing of these nutrients is critical for optimum crop response, so they need to be applied well before anthesis/flowering usually at the 4-6 leaf stage. Later applications of copper & magnesium at booting/flag leaf stage can also be beneficial on deficient soils and should be easily identified with tissue analysis.

For canola & legume crops, boron is a particularly important nutrient for flowering & seed yield. Boron is required for pollen tube development and low boron levels inhibit pollen tube growth thus significantly reducing the likelihood of successful fertilization. Again boron needs to be applied early prior to flowering, however for canola, good results have also been achieved with foliar sprays during the bolting-early flowering period. Foliar boron is a very safe option as there is little chance of inducing toxicity that can be an issue with soil application. Legume crops also respond very well to zinc and manganese sprays, prior to, as well as post-flowering.

Another nutrient that can have a significant impact on yield is magnesium. Deficiencies are usually seen on sandy acid soils but can also be induced by high soil potassium levels or application of ammonium fertilizers. Like zinc/copper/manganese, magnesium also drives sugar/starch production critical for optimum seed set so early application is important, however crops also respond well to foliar magnesium sprays later in the season.

Molybdenum is an important trace element for broadacre production. Moly is essential for germination, anthesis in maize crops, nitrogen fixation in legumes & the conversion of soluble nitrates to amino acids. Cereals with molybdenum deficiency can be significantly stunted and yields reduced by up to 30%. Molybdenum deficiency is common on acid soils & often application of lime can correct the issue. Application of sulphates (eg. gypsum) can also reduce uptake of the molybdate anion due to competition in the root zone. Copper & molybdenum have an antagonistic relationship in the soil (high copper will reduce moly uptake & vice versa). Soil application at seeding is a common practice, however if soil pH is not corrected, availability will be limited. Mo is plant (phloem) mobile so foliar sprays are highly effective with only low rates required to correct a deficiency.

A lesser utilized foliar nutrient is phosphorous. Obviously being a major nutrient it is critical for crop production in both the early and later stages of development. On most soil types phosphorous has low availability (<15%) and therefore growers have traditionally over-applied P fertilizers to compensate for this low efficiency. However we have found that even on soils with good Colwell P levels (eg. >60 ppm), crops will still respond to foliar P sprays even though tissue analysis is indicating “Adequate” P status. Another benefit we have observed is that foliar P sprays encourage root uptake of trace elements which can be clearly seen in tissue analysis following application. In the field we have also noted that this can enhance drought tolerance and increase wheat protein levels.

For stressed crops, complete nutrient options such as VLP & GREENA can aid recovery by supplying essential available nutrients at a time when soil availability & root uptake is restricted.

Also check out this Tech Sheet that discusses the different forms of foliar nutrients available to growers and the advantages of SJB Chelates.

Soil Nutrients – Nitrogen and potassium are the biggest nutrient requirements for almond crops and generally it is recommended that about 1/4 of the total N & K requirements are applied post-harvest, however this should be assessed based on the current season’s crop load. Almonds use these nutrients to supply energy and sugars for flower and early shoot development for the next season. It is critical to ensure soil moisture levels are optimal when N & K are applied (or any soil fertilizer for that matter) otherwise fertilizer efficiency/uptake will be low and there is also potential for root damage in dry soils due to the high salt index.

Phosphorous is essential for reproduction, energy production (eg. ATP) and cell division. While almond trees do not have a large P requirement (30 kg P/ha for maintenance in bearing trees) it is critical during the bud-burst to fruit set period so it needs to be available as soon as roots become active in late winter. If soils are low in sulphur then applying Single Super post-harvest will be beneficial, while more available forms (eg. MAP/DAP/MKP/APP) should all be applied pre-flowering & during early fruit development.

Some growers may also be applying phosphonate (eg. PHOSIC 600) post-harvest to address any phytophthora concerns. While some companies may claim that the phosphorous (eg. phosphite) in their phos acid products is available to the trees as a nutrient source, this is simply not true at least in the short to medium term. Phosphite that remains in the soil will over time (eg. 6-12 months) be converted to the plant available phosphate form, however it should not be relied upon as a P nutrient source for the coming season. Growers should also be aware that the phosphite MRL for almonds going into Europe has been lowered to 2ppm as of Dec 31 2015, so you may need to find an alternative product if your nuts are going to this market.

Post-harvest is also a good time to apply calcium if exchangeable levels are low in the soil or pH needs adjusting. While calcium may be considered a less important nutrient by many, my experience in the field indicates that there is a direct relationship between tissue calcium levels and kernel yield. Calcium is also an important nutrient for reproduction and pollen tube development, so it is essential that tree calcium levels are optimal before they go into dormancy (pre-flowering application of calcium nitrate will also be beneficial).

Zinc and boron are both essential trace elements for almond production and are required for reproduction, shoot development and fruit filling. In seasons where you have average to good yields with good shoot development, demand for boron and zinc will be high so levels in the trees may be depleted and therefore post-harvest application is even more critical in this situation. Boron is quite mobile in lighter soils & so has good availability but can also be lost through leaching if over applied. If soil boron levels are <0.5 mg/kg then look at applying 1-2 kg B/ha. If boron hull levels are also <80 mg/kg consider the higher rate. Unlike boron, zinc is basically immobile in the soil and therefore soil application is less efficient, particularly if soil pH is alkaline. Best zinc availability will be seen on sandy acid soil types where exchangeable zinc is <2 mg/kg. Young trees will usually benefit the most from regular soil zinc application. Look at applying 1-2 kg Zn/ha.

Foliar Nutrients – Post-harvest foliar sprays are essentially aimed at ‘bud building’ for the coming season and nitrogen, zinc and boron are the main nutrients of interest in this regard. Lo bi urea is used in many crops to aid bud development/health and the Almond Board recommends applying a 1% solution (eg. 1 kg urea/100L) in late April and early May. Numerous studies in almonds indicate a consistent benefit from post-harvest foliar boron sprays in terms of improved fruit set and nut retention in the following season (250-500 g B/1000L). Given the high boron requirement for almond production, I would still recommend both soil and foliar application, particularly on low boron soils. Like boron, foliar zinc has also shown to be beneficial for bud development and fruit set, mainly due to its role in auxin production (an essential plant growth hormone).

While there are various factors that determine potential fruit set, nutrition is one that (unlike the weather) can be controlled & manipulated by growers to ensure their trees have the best chance of setting an optimal crop.

Defoliation – There has been some discussion on the best option for defoliation of trees prior to dormancy. Traditionally, high or phytotoxic rates of zinc sulphate have been used and it was thought this would provide some zinc to enhance bud development for the coming season. The other alternative is to use high buiret urea (eg. 70 kg/1000L) to defoliate. In terms of foliar absorption, nitrogen is absorbed much faster (hours) than zinc (2-5 days) which only has limited plant mobility. Also the condition or health of leaves has a major effect on foliar uptake and at this time of the season the condition of leaves is usually not that suitable for foliar uptake anyhow. So the reality is that zinc sulphate will probably not supply any available zinc for the coming season, whereas urea is more likely to supply some nitrogen for bud development.

SJB Soil Applied Nutrients

Boron PLEX

Calcium + Boron PLEX

Zinc PLEX

SJB Foliar Applied Nutrients for Bud-building

LIGNO-BORON

LIG-TRACE

LIG-ZINC

LIG-ZINC + BORON

Systemic Fungicide for Phytophthora Control

PHOSIC 600 (can be applied to the soil or as a foliar spray)

Zinc is the most common trace element deficiency in Australian crops & addressing it early in the season is essential for optimum crop growth & quality.

Read more

With optimal growing conditions in 2016, vegetative growth & yield potential of wheat crops is high and with this comes the risk of significant yield losses due to lodging later in the season. Lodging is the result of poor structural integrity (strength) of stems usually caused by excessive vegetative growth (ie. optimal soil moisture & high nitrogen availability) in high yielding crops where stems are not able to support the weight of the dense canopy & loaded heads. Late season rain and wind also compound this issue.

Nutrition does play an important role in the severity of lodging losses and there are a number of key nutrients that need to be managed well to avoid significant yield losses. Nitrogen of course is the highest input nutrient for cereal production and has a significant effect on vegetative growth and grain protein. The key for nitrogen is not to put too much on too early but try and split applications if possible to reduce excessive vigour during stem elongation. Applying early molybdenum sprays on susceptible soils (eg. strongly acid) will help nitrogen (nitrate) conversion & reduce excessive vigour & weak stems.

Optimising levels of key essential nutrients that play important roles in structural integrity is also critical for reducing lodging losses. The three major ones are calcium, copper and boron. Calcium is an essential component of all cell walls and vital for building strong plants. While calcium demand is lower for cereals compared to canola and pulses, it is still required is reasonable amounts (>5000 mg/kg DM). Furthermore, high nitrogen combined with excessive vegetative growth increases calcium demand often leading to a dilution of cellular calcium thus making crops more prone to structural weakness & disease issues. In-crop foliar sprays can be helpful, however the bulk of the calcium supply comes from the soil and this really needs to be addressed pre-sowing as post-emergent soil application is usually too slow to be of major benefit.

Copper deficiency is common in cereals grown on a wide variety of soil types throughout Australia. Alkaline soils or those high in organic matter, lock up copper making it unavailable to the crop. Crops grown on many of the heavily leached acid sands in Western Australia also have significant copper deficiency issues due to the very low levels of residual copper. Copper is required for the lignification of stems and deficiencies greatly reduce the crop’s physical strength & ability to resist disease attack. Nutrient balance is important here as high nitrates reduce copper uptake while also increasing copper demand for vegetative development. Copper is also essential for anthesis & seed set so if you are on low copper soils you should be applying at least one early foliar spray (4 leaf) as standard practice & possibly another at booting if yield potential is high.

Boron like calcium is a key component of cell walls, hence its importance for plant structure. Some of you may be a bit wary about applying boron on wheat as usually it is associated with toxicities rather than deficiencies in cereals. However if tissue levels are low (< 4 mg/kg) there can be positive responses to foliar boron application in terms of reduced lodging and improved anthesis. Boron also facilitates calcium uptake so provides additional benefits with regard to plant health and strength.

Looking at overall nutrient balance, growers should also keep an eye on potassium and magnesium levels in relation to nitrogen. These nutrients are important for sugar and carbohydrate production and help balance the detrimental effect of excessive nitrogen on crop health and development.

Foliar nutrient options for Wheat

4-5 leaf – LIG-GRAIN PLUS (Zn, Cu, B, Mo) @ 2 L/ha, LIG-ZINC + Cu @ 1 L/ha, LIG-COPPER @ 1 L/ha, Pasture Cal @ 2-3 L/ha.

Looking for a calcium, boron & moly product? Talk to us about LIG-CBM (Ca 8%, B 1%, Mo 0.25%).

Booting/pre-anthesis – LIG-COPPER @ 1 L/ha.