WO2014127471A1

WO2014127471A1 - Foliar zinc fertilizer

Info

Publication number: WO2014127471A1
Application number: PCT/CA2014/050103
Authority: WO
Inventors: Mark Goodwin
Original assignee: Wolf Trax Inc.
Priority date: 2013-02-19
Filing date: 2014-02-14
Publication date: 2014-08-28
Also published as: CA2938171A1

Abstract

The uptake of foliar-applied zinc this is influenced by humidity. Specifically, uptake is negatively impacted if the zinc is applied under low humidity, as the zinc is "locked up" by leaf waxes as the droplet dries on the surface of the leaf, thereby rendering the zinc useless. Described herein is a foliar zinc fertilizer comprising (a) zinc sulphate in combination with a mixture of (b) urea and (c) a substance with a suitable point of deliquescence (POD) such as organic surfactants, calcium chloride, magnesium chloride or combinations thereof.

Description

FOLIAR ZINC FERTILIZER

PRIOR APPLICATION INFORMATION

The instant application claims the benefit of US Provisional Patent Application 61/766,257, filed February 19, 2013.

FIELD OF THE INVENTION

The present invention relates generally to the field of fertilizers. More specifically, the present invention relates to a foliar zinc fertilizer having increased uptake and transportation of the zinc through the plant

BACKGROUND OF THE INVENTION

Crop response to foliar applied zinc in the field is an extremely complex process. Efficacy depends on the nutrient status of the plant, the species in question and the timing of application and environmental factors. Many crops have a high need for zinc but an accompanying inability to move the zinc from the point at which foliar applied zinc hits the leaf, to points through the crop where the zinc is needed. For instance, almonds have a high zinc requirement but less than 3 percent of foliar applied zinc actually moves from point of interception to sites within the crop where the zinc can be effectively used.

As will be readily apparent to those of skill in the art, there are two challenges in attaining efficacy with foliar applied zinc. These two challenges are: attaining penetration through epicuticular wax and movement of the zinc from the leaf to other parts of the plant that require the nutrient SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a foliar zinc fertilizer comprising zinc sulphate in combination with urea at 0.5 to 2% (v/v) and a point of deliquescence (POD) adjusting compound with a suitable POD.

According to a second aspect of the invention, there is provided a method of enhancing zinc uptake in a plant in need thereof comprising: applying a foliar zinc fertilizer comprising zinc sulphate in combination with urea at 0.5 to 2% (v/v) and a point of deliquescence (POD) adjusting compound with a suitable POD to the leaves of said plant; and

growing the plant under suitable conditions for promoting growth of said plant.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1. Zinc transported to untreated leaf tissue on terminal ends of branches.

Figure 2. Zinc uptake efficacy in lettuce.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are now described. All publications mentioned hereunder are incorporated herein by reference.

As discussed herein, the inventor has made the surprising discovery that the uptake of foliar-applied zinc this is influenced by humidity. Specifically, uptake is negatively impacted if the zinc is applied under low humidity, as the zinc is "locked up" by leaf waxes as the droplet dries on the surface of the leaf, thereby rendering the zinc useless.

Specifically, wax hinders the penetration of water and nutrients across the membrane. Various aspects of foliar nutrition with different inorganic salts have been studied but only a few examine cuticular penetration of ions and salts. Some work shows that with increasing humidity, rate of penetration increased because cuticles swelled. However humidity's main effect was related to dissolution of salt residues on the surface of cuticles. This process is governed by the point of deliquescence (POD) which is the humidity over a saturated salt solution containing solid salt. Penetration requires dissolution of the nutrient salt. This is determined by the point of deliquescence (POD) of the salt relative to humidity over the salt residue. POD is defined as that humidity over a saturated solution containing solid salt. When humidity is above the POD, the salt residue on the cuticle will dissolve. When humidity is below the POD, a solid residue is formed and penetration ceases. Work at UC Davis and other places has determined that the lower the POD, the better the penetration. For example, Lithium Chloride has a POD of 11.3%, Sodium Bromide has a POD of 58%, Sodium Chloride has a POD of 75%, KCI has a POD of 85%, Potassium Nitrate has a POD Of 94%, CaCb has a POD of 33%, MgCh has a POD of 33%, K2CO3 has a POD of 56%, Mg(NO₃)2 has a POD of 56% and ZnSO₄ has a POD of approximately 90%. Furthermore, the point of deliquescence can be determined for any compound by determining the relative humidity at which the material starts absorbing available moisture.

Regarding the transportation of the nutrient throughout the plant, many workers have tested various additives and plant hormones combined with zinc were tested to determine if the amount of zinc that entered the plant could be more effectively moved from the point of entry through to other growing tissue within the plant.

One oft-cited means of hastening transport is through the addition of urea to mixes of foliar zinc. Some researchers cited enhanced movement through the plant of the zinc when urea was added to the spray mix. L.J. Grauke (1982) found The inclusion of NH4NO3 and urea to either Zn(NO3)2 or ZnSO4 resulted in a significant increase in translocation of absorbed zinc. (The Influence of Zinc Carriers on the Foliar Absorption of Zinc by Pecan and Corn. Ph. D. Dissertation, Texas A&M University, College Station, TX, 1982) Others attained diametrically opposite results with the addition of urea doing absolutely no good in enhancing zinc movement. Urea results - Haslett et al (2011) showed no impact in terms of increased shoot growth vs zinc alone on wheat. Zinc Mobility in Wheat: Uptake and Distribution of Zinc Applied to Leaves or Roots UC Davis (1986) reports actual reductions through use of urea vs zinc alone.

None of these researchers identified humidity management as a central reason as to why the differences in the efficacy of the urea occurred. The average humidity at College Station (where the urea worked) exceeds 94 percent by early July three days out of every four. The average humidity at the research facilities where the urea did NOT work was low. At University of Western Australia (Haslett) humidity is below 50% on average (1942 to 1992 average) and the UC Davis Humidity is very low in the summer - usually in the 15 - 30% range.

While not wishing to be bound to a particular theory or hypothesis, the inventor believes that in instances where the urea was not effective in enhancing transportation, the process was stopped because initial transport across the leaf was impeded by low humidity accompanied by the lack of appropriate POD additives. As will be readily apparent to one of skill in the art, urea cannot transport nutrients through a plant if the nutrients are stopped by the leaf wax before the nutrient even enters the plant.

Described herein is a foliar fertilizer combination of two ingredients that will (a) enhance zinc uptake and (b) enhance movement through the plant. By including both ingredients, one can in fact consistently take advantage of the capacity of the urea to enhance translocation.

As discussed herein, two additives are combined with zinc, with the first additive (designated as POD Adjuster or PODAdj) is designed to decrease the POD and the second additive (designated as transport enhancer or TrEnh) is designed to drive transport of the zinc throughout the plant.

As will be appreciated by one of skill in the art, any suitable POD compound can be used provided that the resulting POD is lower than the relative humidity at the time of application and uptake.

The POD adjuster may be any compound that decreases the POD of ZnSO4, for example, a suitable organic surfactant, calcium chloride or magnesium chloride.

While not wishing to be bound to a particular theory or hypothesis, the inventor believes that the POD adjuster keeps the composition "wet" so that the leaf wax does not lock up the nutrient solution, and this allows for penetration of the zinc/urea through the epicuticular wax. The area then acts to enhance distribution of the zinc, moving the zinc away from the leaves and further within the plant, which in turn allows more zinc to be taken up.

The suitable organic surfactant may be selected from the group consisting of: an alkylnaphthalene sulfonate surfactant (MORWET®), an alcohol ethoxylated surfactant (AGNIQUE®), nonylphenoxy polyethyoxyethanol (Agral™ 90), formulated amine alkoxylate (ADSEE907™) as well as other suitable non-ionic surfactants known in the art.

The transport enhancer may be urea.

The foliar zinc fertilizer comprises (a) a high analysis of zinc sulphate (up to 98% zinc sulphate), (b) a POD altering agent or compound at 0.2 to 2.0%, preferably 0.5 to 1.5% of the fertilizer selected from (i) an additive with hydroscopic properties (such as Agnique, Morwet) and/or (ii) an anhydrous low molecular weight acids such as anhydrous citrate, anhydrous magnesium sulphate, magnesium chloride, calcium chloride, and the like; and (c) a transport enhancer, specifically urea.

The foliar zinc fertilizer is intended for application to any suitable agricultural crop in need of enhanced zinc uptake, including but by no means limited to horticultural crops, field crops, fruit trees, nut trees and ornamentals.

As discussed herein, the invention comprises a "two step" combination wherein the PODAdj (POD altering element) works at the interception phase as the nutrient droplet strikes the leaf, acting to keep that droplet wet during the time the urea/zinc are passing through the leaf wax. The TrEnh (transport enhancer) then acts to facilitate movement of the zinc through the plant, having benefited from the maximized plant entry conferred on the solution by the POD agent.

In a preferred embodiment, the foliar zinc fertilizer comprises (a) zinc sulphate in combination with a mixture of (b) urea at 1 to 2 % and (c) a substance with a a POD below 40 such as organic surfactants, caicium chloride, magnesium chloride or combinations thereof, as discussed above.

In a preferred embodiment, 0.2-2.0% POD adjuster(v/v) and 0.5-2.0% urea (v/v) are added to ZnSO₄.

More preferably, the zinc is present at 96-99.3% (v/v) of the foliar zinc fertilizer. In one embodiment of the invention, there is provided a foliar zinc fertilizer comprising an effective amount of zinc sulphate in combination with urea at 0.5 to 2% (v/v) and a substance with a POD below the average ambient humidity.

As will be appreciated by one of skill in the art, the average ambient humidity for a given region or area can be easily determined, calculated or estimated using data available through any of a variety of weather services or web sites.

The POD below the average ambient humidity may be for example, 40%.

As will be known to one of skill in the art and as discussed above, the PODs for a large number of compounds suitable for use within the invention are well known as are methods for determining the POD of potential POD adjusters. However, some examples of suitable POD adjusters include but are by no means limited to organic surfactants, calcium chloride, magnesium chloride or combinations thereof, as discussed above.

As will be appreciated by one of skill in the art, the above-described foliar zinc fertilizer is taken up at a much higher rate than conventional foliar zinc fertilizers. Accordingly, in some embodiments of the invention, the above-described foliar zinc fertilizer can be applied at a rate that is for example 40% or less than traditional zinc fertilizers. Alternatively, a similar rate may be used so that higher levels, for example, 40% or more zinc, is taken up, compared to a similar foliar zinc fertilizer known in the art.

The invention will now be further explained by way of examples; however, the invention is not necessarily limited to or by the examples.

As shown in Figure 1 , zinc foliar treatments were applied to the leaves of apple trees. The ends of branches were covered so that the leaves thereon did not receive any zinc foliar spray. The relative humidity was 50 percent on the day of spraying. The sprays were applied in approximately 400 L per hectare rates. There were three trees per treatment and the uptake and movement of zinc was measured 7 days after treatment.

As can be seen from Figure 1 , ZnSO4 was applied at 1.5 kg/ha in all treatment groups. In treatment group 1 , zinc powder alone was applied and 102 ppm was taken up. In treatment group 2, ZnSO4 was applied together with 1% urea. As can be seen, zinc uptake was in fact reduced significantly (almost 50%) compared to treatment group 1. In treatment group 3, POD agent #1 was added and zinc uptake increased by almost 50%. In treatment group #4, POD agent #2 was added and zinc uptake increased almost 100%. In treatment group 5, urea and POD agent #2 were added. As can be seen in comparison with treatment group 2, addition of the POD agent #2 counteracted the negative impact of the addition of urea on zinc uptake such that not only was zinc uptake increased by almost 100% compared to zinc alone, zinc uptake was increased almost 300% compared to zinc and urea. In treatment group 6, both POD agents #1 and #2 and urea were added which resulted in a slightly higher zinc uptake than treatment groups 4 and 5, indicating an additive effect.

Thus, as discussed above, the urea, when added to the zinc did not improve the translocation of zinc to the unsprayed leaves - as per the result by Haslett et al . But when the urea was added in concert with substances with points of deliquescence below the relative humidity, the urea was able to enhance translocation in a manner equal to that seen by L.J. Grauke (1982).

It is important to remember that this data relates to the levels of zinc in untreated terminal portions of the branches. Thus, the foliar zinc fertilizer is clearly being transported or distributed from the treated leaf tissue portions of the branch to the covered, terminal areas of the branches.

Regarding Figure 2, in all treatment groups, 36% ZnSO₄ was applied at 0.45 kg/ha. In treatment group 1 , zinc alone was applied and 307 ppm zinc was taken up by the lettuce. In treatment group 2, urea was added and uptake of zinc improved slightly. It is important to note that unlike the previous example, urea did not inhibit uptake and in fact appears to have slightly enhanced zinc uptake. In the third treatment group, 1 % citrate was added and zinc uptake increased almost 100%.

The foliar zinc fertilizer may be used in the following manner.

Fruit trees/nuts - up to 1.5 kg per ha of product. Use of the PODAdj/TrEnh technology would be such that up to 1.5 kg per ha of the product be sprayed and that the PODAdj plus TrEnh combination would approximate a total of 2% of the total product weight with 1 % being urea (TrEnh) and 1 percent being combinations of POD adjusters (anhydrous citrate and one of two commercial additives as noted above - ie Agnique or Morwet).

Annual crops - up to 0.45 kg per ha kg per ha of product. Use of the POD/TrEnh technology would be such that up to 0.45 kg per ha of the product be sprayed and that the POD plus TrEnh combination would approximate a total of 2% of the total product weight with 1 % being urea (TrEnh) and 1 percent being a POD adjuster (in this example, anhydrous citrate is used)

While the preferred embodiments of the invention have been described above, it will be recognized and understood that various modifications may be made therein, and the appended claims are intended to cover all such modifications which may fall within the spirit and scope of the invention.

Claims

1. A foliar zinc fertilizer comprising zinc sulphate in combination with urea at 0.5 to 2% (v/v) and a point of deliquescence (POD) adjusting compound with a suitable POD.

2. The foliar zinc fertilizer according to claim 1 wherein the POD adjusting compound is selected from the group consisting of organic surfactants, calcium chloride, magnesium chloride and combinations thereof.

3. The foliar zinc fertilizer according to claim 1 wherein the suitable POD adjusting compound has a point of deliquescence below an average ambient humidity for the region of application.

4. The foliar zinc fertilizer according to claim 1 wherein the POD adjusting compound is at 0.2-2.0% (v/v).

5. The foliar zinc fertilizer according to claim 1 wherein the zinc sulphate is between 96-99.3% (v/v) of the foliar zinc fertilizer.

6. A method of enhancing zinc uptake in a plant in need thereof comprising:

applying a foliar zinc fertilizer comprising zinc sulphate in combination with urea at 0.5 to 2% (v/v) and a point of deliquescence (POD) adjusting compound with a suitable POD to the leaves of said plant; and

growing the plant under suitable conditions for promoting growth of said plant.

7. The method according to claim 6 wherein the POD adjusting compound is selected from the group consisting of organic surfactants, calcium chloride, magnesium chloride and combinations thereof.

8. The method according to claim 6 wherein the suitable POD adjusting compound has a point of deliquescence below an average ambient humidity for the region of application.

9. The method according to claim 6 wherein the POD adjusting compound is at 0.2-2.0% (v/v).

10. The method according to claim 6 wherein the zinc sulphate is between 96-99.3% (v/v) of the foliar zinc fertilizer.