WO1997032830A1

WO1997032830A1 - Foliar administration of microelements to plants

Info

Publication number: WO1997032830A1
Application number: PCT/IL1997/000081
Authority: WO
Inventors: Yoram Tsivion
Original assignee: LEKET BAR CHEMICALS Ltd
Current assignee: LEKET BAR CHEMICALS Ltd
Priority date: 1996-03-08
Filing date: 1997-03-06
Publication date: 1997-09-12
Anticipated expiration: 1998-09-08
Also published as: AU1810397A; AR006151A1; IL117418A0

Abstract

A plant nutrient composition for application onto aerial plant parts comprising one or more polyvalent metal ions and solubilization agent which maintains said one or more ions in aqueous solution. The agent is a combination of (a) alcoholic alkylamine and (b) a chelating agent being an organic acid or a derivative thereof.

Description

FOLIAR ADMINISTRATION OF MICROELEMENTS TO PLANTS

FIELD OF THE INVENTION

The present invention is generally in the field of plant nutrition and relates to administration of metal ion microelements, which are poly¬ valent metal ions needed by the plants. More specifically, the invention relates to administration of such metal ions to aerial plant parts of plants (trunk, branches and leaves).

BACKGROUND OF THE INVENTION AND PRIOR ART

Metal ion microelements, including iron (typically as a trivalent ion), manganese, zinc, copper, calcium and magnesium, are a needed ingredient and plants often require a supplement thereof. Nutrients, including microelements, can be administered to plants either through their roots or through aerial parts of the plants. Aerial administration to the parts of the plant above the soil can be achieved by injecting a nutrient composi- tion into the trunk or spraying such a composition onto branches or leaves. Root application has a variety of advantages including little required labor (the fertilizer composition can be applied through the irrigation system), being practically independent of weather conditions, and generally having (where applicable) high effectivity. However, the soil as well as the type of plant is at times unsuitable for such administration. For example, in alkalinic or calcareous soils, salts of the di- or tri-valent metal ion microelements precipitate and become scarcely available for absorption through the root. In such cases, it may be useful to apply the microelements through aerial plant parts. In addition to being independent of soil conditions, aerial application of nutrients is at times advantageous by itself, in that the plants respond relatively faster to such administration, and further in that very often a small amount of the nutrients are required Surfactants are routinely added to plant nutrient compositions for aerial applications (to be referred to hereinafter at times as "aerial composi¬ tions ") to ensure a spread of the liquid compositions conditions on the aerial parts of the plant, (primarily leaves) and facilitate the absorption of the nutrients into the plant. In addition, chelates have to be added to ensure that the metal ions remain soluble in solution on the one hand (i.e. to avoid precipitation of their salts) and to allow their absorption by the plant on the other hand (Swietlik, D. and Faust, M. Hort. Rev. 6:287-346, 1984).

Several types of complexing or chelating agents have been proposed for use in aerial compositions including EDDHA and EDTA (Swietlik et al., supra), of EDTA or citric acid (CA-1, 152,769) and others. The strength of which the chelate holds the metal ions was noted to have an effect on the absorption of the associated metal ions by the plant tissue. Generally, a chelating agent which strongly complexes with the metal ion does not easily release it in situ to allow it to be absorbed into the plant. Against this, a weak chelating agent often becomes less effective when the pH is raised to neutral pH, which is required so as not to damage aerial parts of the plant.

Di- or tri-carboxylic organic acids, such as citric acid complex with poly-valent ions. However, in such compositions the pH has to be raised, as noted above. In the art of aerial compositions raising of the pH following mixing of the metal ions with the organic acid was achieved by the use of ammonia (CA-1, 152-769, HU-200147, US-3,869,272 and US-4,265,653). Citric acid is initially effective as a chelating agent also when the pH is raised, but over time, particularly when the composition is stored in a cold temperature, e.g. in the winter, components tend to crystalize and precipitate in such a solution. When organic acids which are weaker chelates, such as malic acid are used, raising the pH brings to the rapid formation of precipitates. It should be noted that plant nutrient solutions are typically prepared and stored as concentrates which aggregates the issue of precipitation. SUMMARY OF THE INVENTION

The present invention provides a novel formulation for aerial applications of metal ion micronutrients to plants. The metal ion micro- nutrients include a variety of poly-valent metal ions such as Fe⁺³, Fe⁺², Mn⁺², Cu⁺², Zn⁺², Ca⁺² and Mg⁺².

The present invention is based on the discovery that a combina¬ tion of a hydroxy alkylamine (which is a non-complexing agent) and a carboxylic acid chelate is an effective carrier of the metal ion micronutrients for areal application. It was found in accordance with the invention that when ethanol amine, as a representative of the group of hydroxy alkylamine compounds, is used as an agent to raise the pH after mixing an organic acid chelate with the poly-valent metal ion, no precipitation occurs at the higher pH even after a long storage period. Thus, in accordance with the invention, a delicate balance is achieved between seemingly two contradictory require¬ ments: the need to allow effective solubilization of the poly-valent metal ions to avoid precipitation even in prolonged periods of storage on the one hand, and the ability to provide for chelation which allows effective release of the poly-valent metal ion and its absorption into the plant at inoffensive pH values.

The present invention thus provides an aqueous plant nutrient composition for application onto aerial plant parts ("aerial plant composi¬ tion "), comprising one or more poly-valent metal ions and a solubilizing agent which maintains said one or more ions in solution, said agent being a combination of a hydroxy alkylamine and an organic acid chelate.

The present invention also provides a method for administering poly-valent ions to plants, comprising spraying plants with a solution comprising said ions together with said solubilizing agent.

Also provided by the present invention are concentrates for preparing, by dilution with water, said aerial plant composition. Such concentrates will comprise all ingredients, namely, the poly-valent metal ions, the hydroxy alkylamine, and the organic acid chelating agent, at the same ratios as in the aerial plant composition to be prepared therefrom.

In a concentrate of the invention, typical concentration ranges of the metal ions, the hydroxy alkylamine and the organic acid chelating agent, and preferred ranges are as follows: Typical concentration:

Metal ions: 2-13%

Hydroxy alkylamine: 10-35%

Organic acid: 20-40% Preferred ranges of concentration are as follows:

Metal ions: 8-13%

Hydroxy alkylamine: 20-30%

Organic acid. 25-30%

The above indication of % is weight/volume, namely, gram weight/100 ml of solution.

Prior to use, the concentrate is diluted with water. Typical dilution ratio is 1:300-1:500, with the application water.

The present invention also provides a process for preparing said aerial plant composition or said concentrate, comprising mixing one or more poly-valent ions with said solubilizing agent.

In accordance with one embodiment of the process, the poly¬ valent ions are first mixed with an aqueous solution of said organic acid chelate and after solubilization, the alcoholic alkylamine is added until achieving a desired pH, e.g. a pH in the range of 3-8. The present invention also provides a method for the administra¬ tion of poly-valent metal ions to plant, comprising:

(a) preparing an aqueous solution of said metal ions with a solubiliz¬ ing agent being a combination of a hydroxy alkylamine and an organic acid chelate; and (b) spraying the solution onto aerial parts of the plant The composition and the concentrate of the invention may at times also comprise a surfactant such as Triton X-100, e.g. at a concentra¬ tion of 0.02-0.06%.

The hydroxy alkylamine may be a compound having the following general Formula I:

OH-(CH₂)_n-N

wherein R_j and R_: are independently hydrogen or a OH-(CH₂)_m- group, m and n being independently an integer between 2-6. A preferred hydroxy alkylamine in accordance with the invention is mono, di or tri- ethanol amine.

The second component may be chosen from a wide variety of organic acids which have a chelating activity. The organic acid may be a non-substituted organic acid, or may be an organic acid carrying a substituent which either does not substantially reduce the chelating properties of the organic acid or improves such chelating properties. Examples are: polycarboxylic acids, e.g. citric acid, malic acid, tartaric acid, oxalic acid; carboxylic acid carrying an acid forming or base forming substituent (at position a, β, etc.), e.g. aminocarboxylic acid, hydroxycarboxylic acid, carboxylic acids substituted with a sulfonic group, carboxylic acids substituted with a keton group; aromatic acids, e.g. salicylic acid, sulfosali- cylic acid, caffeic acid; sulfonic acid. Preferred organic acid chelates in accordance with the invention are citric acid, malic acid and sulfosalicylic acid.

The composition of the invention has preferably a pH in the rantze of about 2.5-8. most desirablv about 3-7. It was found in accordance with the invention that in a permissive pH, for aerial application, e.g. about 3-8, there is no precipitation of the poly-valent ions which are thus available for absorption into the plants.

Example 1

155 grams of malic acid (food grade) was mixed with 300 grams of ferric chloride hexahydrate. 300 ml of water was then added and the entire mixture was stirred. This mixture was turbid evidence to the formation of insoluble precipitates. 300 ml of EA was then added to the mixture whilst stirring. In a few seconds the solution turned to be fully clear evidence of the complete solubilization of the salt and acid. Final volume of the solution was 820 ml with a final pH = 7.

Example 2 A composition similar to that described in Example 1 was prepared but with citric replacing the malic acid. 223 grams of citric acid were mixed with 310 grams of ferric chloride hexahydrate and to this 290 ml of water was added. After 30 min. of mixing a clear solution was formed. The final volume solution was 600 ml with a final pH <1. Although effective chelation is achieved in such a solution it is unsuitable for aerial application because of its very acidic pH.

Example 3

45 grams of salicylic acid was sulfonated with 37 ml of sulfuric acid. To the resulting slurry 60 ml of water was added. Then 45 ml of water was mixed with 120 ml EA, then 78 grams of ferric chloride hexahydrate was added. After stirring, 300 ml of clear solution was obtained with a final pH = 2.3. The pH can be elevated by the addition of additional amounts of EA without formation of insoluble precipitates. Example 4

To 500 ml of water 83.3 grams of ZnS0₄-7H₂0, 70 grams of MnSCylH₂0, 56 grams CuSCy5H₂0, 147 grams FeCl₃-6H₂0 and 282 grams citric acid were added. Water was then added and mixed to complete the volume to 1 liter. After one hour a clear solution of 320 ml EA was added and the resulting product was entirely clear evidenced to the full solubilization of the salt. The final volume solution was 1184 ml and the pH was 3.8.

Example 5

The solution of Example 3 was refrigerated at 5°C for a period of two months During that time the solution became viscous but after thawing at normal room temperature, it reverted to normal flowability. No crystallization or precipitation occurred.

Example 6

The solution of Example 1 was supplemented with 0.025% of the detergent Triton X-100 (Rohm & Haas) and mixed. The solution was diluted in water to 0.8% v/v. This preparation was tried on the following chlorotic plants: wax flower and roses. Branches on plants were marked and sprayed in the evening, greening commenced in each case within a few days. Unmarked and therefore unsprayed branches did not turn green within a two weeks test period.

Claims

CLAIMS:

1. An aqueous plant nutrient composition for application onto aerial plant parts ("aerial plant composition "), comprising one or more poly-valent metal ions and a solubilizing agent which maintains said one or more ions in solution, said agent being a combination of a hydroxy alkylamine and an organic acid chelate.

2. An aerial plant composition according to Claim 1, wherein said hydroxy alkylamine is a compound having the following general Formula I:

/ R.

OH-(CH₂)_n-N (I)

\ R,

wherein R_j and R₂ are independently hydrogen or a OH-(CH₂)_ra- group, m and n being independently an integer between 2-6.

3. A composition according to Claim 2, wherein said hydroxy alkylamine is a mono, di or tri- ethanol amine.

4. A composition according to any one of Claims 1-3, wherein said organic acid is citric acid, malic acid or sulfosalicylic acid.

5. A composition according to any one of Claims 1-4, having a pH within the range of about 3-8.

6. A concentrate for the preparation of a composition according to any one of Claims 1-5.

7. A concentrate according to Claim 6, comprising: poly-valent metal ions at a concentration of about 2-13%, hydroxy alkylamine at a concentration of about 10-35%, said organic acid at a concentration of about 20-40%.

8. A process for preparing a composition according to any one of

Claims 1-5 or a concentrate according to Claim 6 or 7, comprising mixing in water one or more poly-valent ions with said solubilized agent

9. A method for the administration of poly-valent metal ions to plant, comprising:

(a) preparing an aqueous solution of said metal ions with a solubiliz¬ ing agent being a combination of a hydroxy alkylamine and an organic acid chelate; and

(b) spraying the resulting mixture onto aerial parts of the plant.