WO2004050583A1

WO2004050583A1 - Nutrient composition comprising an iron chelate

Info

Publication number: WO2004050583A1
Application number: PCT/FI2002/000999
Authority: WO
Inventors: Alain Evrard; Pierre De Rambures; Anders Weckman
Original assignee: Kemira Growhow Oy
Priority date: 2002-12-05
Filing date: 2002-12-05
Publication date: 2004-06-17
Also published as: AU2002346787A1

Abstract

The invention relates to a nutrient composition comprising a Fe-chelate and an acidic component wherein an aqueous solution of said composition is stable and has a pH of at most 5. This composition can be used for the prevention or treatment of iron deficiency in plants growing on alkaline or neutral or slightly acid soil and/or for increasing the yield of the plants.

Description

Nutrient composition comprising an iron chelate

Field of the invention

The present invention relates to a nutrient composition comprising a Fe-chelate especially for use in vineyards on calcareous soil, and to a method for the prevention or treatment of iron deficiency in plants.

Background of the invention

The development of iron deficiency (iron chlorosis) symptoms (growth depression and yellowing of the youngest leaves) and the distribution of iron between roots and leaves have been investigated in different vine cultivars (Silvaner, Riparia IG and S04) grown in calcareous soils. All cultivars including S04 showed severe shoot growth depression, by 50% and higher, before yellowing started or without leaf yellowing in the cultivar S04. Accordingly, depression of shoot growth of nonchlorotic plants under calcareous soil conditions and with ample supply of nutrients and water has been evidenced to be at least partly an iron deficiency symptom. It is suggested that plant growth only partially recovered because of dramatic apoplastic leaf Fe inactivation and/ or a high apoplastic pH which may directly impair growth. The finding of high Fe concentrations also in young, but growth retarded green leaves is a further indication that iron deficiency chlorosis in calcareous soils is caused by primary leaf Fe inactivation. (Journal of Plant Nutrition and Soil Science (2002), 165(1), 111-117).

In a vineyard with severe Fe chlorosis symptoms associated with decreased yield, Fe-EDDHA and FeS04 were applied to the soil, the priniing cuts, or the foliage. Both foliar and soil treatments increased chlorophyll a in apical leaves, sol. solids in berries, cluster weight, and yield per plant. The Fe-EDDHA chelate was more effective than FeS04 in raising chlorophyll level and yield. (Agric. Tec. (Santiago) (1983), 43(3), 249-53).

EDDHA is considered to be the most effective and common Fe fertiliser in general because it forms highly stable ferric complexes in neutral and alkaline solutions. EDDHSA iron chelate was introduced in the market recently. The effectiveness of Fe chelates depends on their ability to maintain Fe in the soil solution despite simultaneous equilibrium of Fe chelate with many cations, such as Ca2+. Both EDDHA and EDDHSA in solution remain fully associated with Fe from pH 4 to 9 despite competition with Ca. The type of chelating agent is a factor that affects chelated Fe availability in soil. Fe-EDDHA were retained more by soil surfaces than Fe-EDDHSA (Plant and Soil (2002), 241(1), 129-137).

Iron EDDHA has long been regarded as the preferred Fe chelate for application to calcareous soils. For example, Fe-EDDHA and Fe-EDDHSA were incubated with two soils from 1 day to 8 wk. They kept a significant amount of the applied Fe in solution for the duration of the experiment. Fe-EDDHSA should be an effective Fe fertilizer for alkaline soils (Communications in Soil Science and Plant Analysis (2001), 32(13 & 14), 2317-2323).

Iron complexes of EDDHSA are used against chlorosis on alkaline soils (EP 0331556A2, US 3903119). These complexes are said to be stable at pH values from 6 to 9. The complexes have been applied to the soil or as foliar as solutions for the treatment of iron deficiency in following plants chrysantemum, soybeans, lettuce, oranges, beans, peanuts and pears (US 3903119, US 3981712, ES 2044777).

Various production methods are developed for EDDHSA (EP 0331556A2, ES 2044777). It is however shown, that the commercial products in many cases include high amounts of inactive components (Journal of Agricultural and Food Chemistry (2002), 50(2), 284-290).

It is known that Fe-EDDHA can be used together with other fertilizers (GB 1319506). One example is the foliar use of methanol together with urea phosphate and EDDHA for eggplant, tomato, strawberry, with the main aim of enhancing carbon fixation in plants (US 5597400).

Sulphuric acid injections are proposed for overcoming Fe-chlorosis in apple trees grown on calcareous soil, and urea sulphate has been used for acidifying alkaline soil. Urea phosphate is used as a fertilizer, especially in fertigation on calcareous soils.

US 5454850 suggests using urea phosphate and the chelates EDTA, DTPA and lignosulphonate in a stock solution for chelating Fe, Zn, Mn and Cu. Many of the chelates effective on neutral soils loose their chelating ability at high alkalinity. The development of EDDHA and its derivatives has overcome this drawback.

In calcareous soils phosphate and several micronutrients, like Fe, Mn, Zn and Cu, are easily immobilized. One way to overcome this problem has been to apply diluted nutrient solutions as drip irrigation. Especially acidic solutions, e.g. based on urea phosphate, have proved to be effective in utilizing micronutrients and improving phosphorus efficiency.

Another approach has been to apply the nutrients as foliar fertilizers. Several problems are related to this method. Nutrients are not easily absorbed through the leaves and the leaves and fruits are sensitive to dosage. The absorbed nutrients are not relocated to new emerging leaves and thus the treatment has to be repeated many times, which is laborious and costly.

A third method is to inject an acidic solution close to the roots of e.g. perennial plants with a woody stem. Such plants are e.g. fruit trees, olive trees, berry bushes or grapevines. The concentrated source of nutrients and acidity will serve as a well, which keeps both the added and mobilized soilbound nutrients in an available form for a time sufficient for the uptake of nutrients. As an example dissolved or applied phosphorus will first form available dicalcium phosphate, which slowly converts into less available forms, like hydroxyapatite, as the pH slowly increase. Typically more available amorphous forms are first formed and the less soluble crystalline forms at a later stage.

Chelates have been tried to overcome the immobilization of micronutrients in calcareous soils. In alkaline conditions most chelates are ineffective because the equilibrium with iron oxides will gradually take place. Another problem is the tendency of chelates to precipitate at pH <4, which will lead to problems in the application. With special designs (e.g. EDDHA, EDDHSA) the effective area has been extended to pH >9 and pH <4. One drawback of these sophisticated designs is the sensitivity to light. When applied on a surface the sunshine will deteriorate the chelate structure.

Although correcting iron chlorosis is one of the main benefits of the chelates, these chelates naturally forms complexes also with other essential micronutrients, e.g. Zn, Mn and Cu.

The main problem to be solved by the present invention is the Fe-deficiency in vineyards, which affects the yield, the quality and the economics of the farmer. Although various foliar applications have been proposed, these could also have a negative effect on the grapes. Soil application of Fe-chelates on calcareous soils has been a problem as the Fe is easily bound to the soil. Acidifying the calcareous soil is not possible as the dissolving CaC0₃ is consuming huge amounts of acid.

A calcareous soil immobilizes the phosphorus into calcium phosphates. These are not easily available for the plants.

When combining Fe-chelates with acids the chelates precipitates from the liquid.

Description of the invention

In a first aspect of the present invention there is provided a nutrient composition comprising a Fe-chelate and an acidic component wherein an aqueous solution of said composition is stable and has a pH of at most 5.

The Fe-chelate is preferably a Fe-EDDHA derivative. Examples of EDDHA (emylenediaminedi (o-hydiOxyphenyl)acetic acid) derivatives are:

EDDHA emylenediaminedi (o-hydroxyphenyl)acetic acid

EDDHSA ethylenediaminedi (2-hydroxy-5-sulfophenyl)acetic acid

EDDHMA ethylenediaminedi (o-hydroxy-p-methylphenyl)acetic acid EDDCHA ethylenediaminedi (5-carboxy-2-hydroxyphenyl)acetic acid.

Many other EDDHA derivatives can also be found in the patent literature, e.g. in EP 0858102. Examples of these are:

emylenediaminedi (2-hydroxy-5-phosphophenyl)acetic acid ethylenediaminedi (2-hydroxy-5-t-butylphenyl)acetic acid ethylenediaminedi (2-hydroxy-3-methylphenyl)acetic acid emylenediaminedi (2-hydroxy-4-methylphenyl)acetic acid ethylenediaminedi (2-hydroxy-3,5-dimethylphenyl)acetic acid ethylenediaminedi (2-hydroxy-4,6-dimethylphenyI)acetic acid emylenediaminedi (2-hydroxy-4,6-dichloroρhenyl)acetic acid.

Also the Fe-EDDHA derivatives disclosed in US 3903119 are useful in the present invention.

An especially preferred Fe-EDDHA derivative is Fe-EDDHSA.

Said acidic component is preferably urea phosphate.

The composition of the invention can also comprise one or several additives, such as a nutrient, crop health improving agent and/or formulating agent. The nutrient can be one or several of the following: primary nutrient (N,P, K), secondary nutrient (Ca, Mg, S) and/or micro-nutrient (Fe, Mn, Zn, Cu, Mo, B, CI). The crop health improving agent can for example be a pesticide, growth regulator or pH regulator. The formulating agent can for example be a dispersing and/or stabilizing agent.

The composition of the invention is preferably in the form of a stable acidic solution or suspension. The pH of the solution or suspension is preferably between about 1.5 and 4.

The nutrient solution or suspension of the invention preferably comprises the Fe- chelate is an amount of from 0.5 to 5% by weight and urea phosphate in an amount of from 0.5 to 5% by weight and additives in an amount of from 0 to 50% by weight.

In case the composition of the invention is in the form of a suspension, the suspension can additionally comprise methylene urea, and optionally a stabilizing agent, such as xanthane gum.

Furthermore, the composition of the invention can be in the form of a solid composition. Such a composition can be dissolved or suspended in water to form a nutrient solution or suspension.

The present invention also relates to the use of the above defined composition for the prevention or treatment of iron deficiency in plants growing on alkaline or neutral or slightly acid soil and/or for increasing the yield of the plants.

In a second aspect of the present invention there is provided a method for the prevention or treatment of iron deficiency in plants growing on alkaline or neutral or slightly acid soil and/or for increasing the yield of the plants, comprising applying to the growing area a nutrient composition comprising a Fe-chelate and an acidic component wherein an aqueous solution of said composition is stable and has a pH of at most 5.

The plants can be perennial wood-stemmed plants, such as grapevines, fruit trees, olive trees or berry bushes, preferably grapevines. The plants can be grown on a soil having a pH of between 6 and 10, and especially on a calcareous soil having a pH of between 7 and 10, especially between 8 and 10.

A preferred embodiment comprises applying the composition in the form of a solution or suspension by injecting into the soil. The combination of Fe-EDDHSA with urea phosphate for injection into the soil makes the Fe possible to take up by the vine. The nitrogen and the phosphorus are also ready soluble and available.

Within a defined solution concentration range the combination of Fe-EDDHSA in the ortho-, ortho-form and urea phosphate stays practically free of solids during injection into the soil.

Other additives, like slow release nitrogen, can be added as solution or stable suspension to the liquid.

The development of the plant is improved when using the injection.

The Fe-EDDHSA is stable both in the acidic range together with urea phosphate and in the alkaline range in the soil.

The uptake of phosphorus is improved when applied as banded near the roots. In calcareous soils the acidity will maintain the solubility of phosphorus for a longer time after application. Acidifying will also mobilize other micronutrients from the soil.

Compared with other mineral acids (HC1, HN0₃, H₂S0 ), urea phosphate is a very safe solid acid.

An improved number of fruits and a better yield were obtained when using injection of Fe-EDDHSA and urea phosphate, thus being beneficial for the plant development.

The use of acidic Fe-chelate solutions or suspensions is in principal applicable for any plants grown on calcareous soils by taking into account the sensitivity of the species. The injection into soil is particularly well applicable for perennial plants with woody stems, like fruit trees, olive trees, berry bushes or grapevines. In addition to urea phosphate and Fe-chelates any other nutrient or additive of importance can also be included.

Fe-chelates are beneficially added as solutions. These can be used in any equipment without causing settling or blocking problems. A particularly beneficial combination is that of urea phosphate and Fe-EDDHSA. This clear acidic liquid is free of solid for a sufficiently long time for the application to be carried out. A Fe- EDDHSA product with a high purity (>90% in o-,o- form) is particularly suitable for solutions. Suspensions can also be used, when the particles are fine and evenly distributed. This can be achieved with additives or by keeping the slowly settling particles in motion by agitation. When solid acid forms of chelates are injected into alkaline soils together with concentrated solutions of the micronutrient, the intimate contact between these in the soil will lead to the corresponding chelate as soon as the pH has increased. For suspensions e.g. Fe-EDDHA can be used together with urea phosphate. In chelate suspensions, other suspendable nutrients (e.g. methylene urea) or additives can be applied. With methylene urea the nitrogen release can be adjusted to fit the need of the plant. The invention will be further illustrated in the following examples. In the examples the "%" is % by weight and the "parts" are parts by weight unless otherwise specified.

Examples

Example 1

Effect of Fe-EDDHSA + UP in a vineyard in France

The effect of the injection of a solution of 50 kg ha urea phosphate and 40 kg/ha Fe- EDDHSA in 2500 liter water, 20 cm from the vines at a depth of 30 cm was compared with the standard fertilization practice on vines without iron addition. The trial consisted of 4 replicates. Each replicate consisted of 4 rows of vines, which were treated with the novel solution and 4 rows of vines, which were treated according to the traditional practice. The traditional practice does not include the application of iron chelates. From each replicate the two middle rows of the 4 treated and the 4 control rows were harvested. The results show the average of the 4 replicates.

The trial was carried out on the grape variety Meunier. The total area where the trial took place covered 1.2 ha. The soil in this area is best described as clay-calcareous. The treatments of the trial and control rows are shown in Table 1. Table 1

During the various growth stages the effect of the soil injection with the combination of urea phosphate and Fe-EDDHSA was followed and compared with the traditional treatment. The yield of grapes was found to be significantly higher in the treated rows. Furthermore it seems that the treatment increases the natural sugar content of the grapes, a very important factor in wine making. The results of the development of grapes are shown in Table 2.

Table 2

In 2001 the average yield of vines treated with Fe-EDDHSA without urea phosphate was lower than the yield obtamed with the trials of the novel solution in 2002 (12.500 kg/ha versus 15.000 kg ha).

Example 2

Formulation and stability of Fe-EDDHSA + UP

The stability of various solutions of urea phosphate and Fe-EDDHSA was tested. The pH of the solutions was measured after 2 hours. The composition, dilution and pH (2h) of UP + Fe-EDDHSA solutions are shown in Table 3. The formation of solids (vol-%) in UP + Fe-EDDHSA solutions is shown in Table 4.

Table 3

*>90% o-,o-form of Fe-chelate

Table 4

The results show that the various solutions of the invention are stable.

Example 3

Comparison of Fe-EDDHA and Fe-EDDHSA

A similar test as in example 2 was carried out for a Fe-EDDHA chelate. The composition and pH after 2 hours of solutions of urea phosphate and Fe-EDDHA are shown in Table 5. The formation of solids (vol-%) in UP + Fe-EDDHA solutions is shown in Table 6.

Table 5

Table 6

The results in Table 6 show that compared to Fe-EDDHSA (Table 4) more solids was produced in the UP + Fe-EDDHA solutions. Revatively stable suspensions are formed and after settling the solids are easily suspended.

Example 4

Comparison of two Fe-EDDHSA chelates

Comparison of commercial Fe-EDDHSA with >90 % o-,o-form of chelate and another commercial Fe-EDDHSA with lower amount of o-,o-form. For three compositions (table 7) the vol-% of settled solids was measured as a function of time (table 8). The composition of the tested solutions is shown in table 7. The solids formation (vol-%) in the solutions containing the two commercial Fe- EDDHSA chelates is shown in Table 8.

Table 7

Table 8

*>90% o-,o-form of Fe-chelate

** <90% o-,o-form of Fe-chelate

The test results show that the Fe-EDDHSA with >90% o-,o-form is more stable than the one with <90% o- o-form.

Example 5

Formulation of Fe-EDDHSA, urea phosphate and methylene urea

When combining 5 parts urea phosphate, 10 parts methylene urea, 3 parts Fe- EDDHSA and 300 parts water a stable suspension can be formed by addmg 0.2% xanthane gum to the solution. Another possibility is grinding the methylene urea and mamtaining a small agitation. The settling time and settling volume for methylene urea in a solution of methylene urea, urea phosphate and Fe-EDDHSA are shown in Table 9.

Table 9

In table 9 the larger settling volumes and almost similar settling times for the grinded methylene urea is due to flocculation of the fine particles.

The minimum stirring speed needed for keeping the particles in motion was measured. The suspension was stirred with a 4.5 cm magnetic rod in a vessel with diameter of 7.5 cm.

For ungrinded methylene urea without additives a speed of 150 rpm was needed to keep the particles off bottom. The corresponding highest peripheral speed was 0.59 m/s. The minimum stirring speed for grinded methylene urea could not be measured, because the particles were dispersed with a very small agitation.

The mean vertical settling rate for ungrinded methylene urea is about 30 cm/min and for grinded methylene urea about 3 cm/min.

Claims

1. A nutrient composition comprising a Fe-chelate and an acidic component wherein an aqueous solution of said composition is stable and has a pH of at most 5.

2. The composition according to Claim 1, wherein the Fe-chelate comprises a Fe- EDDHA derivative.

3. The composition according to Claim 2, wherein the EDDHA derivative is selected from the group consisting of EDDHA, EDDHSA, EDDHMA and EDDCHA.

4. The composition according to any of Claims 1 to 3, wherem the acidic component comprises urea phosphate.

5. The composition according to any of Claims 1 to 4 in the form of a stable acidic solution or suspension.

6. The composition according to Claim 5 wherein the pH of the solution or suspension is from 1.5 to 4.

7. The composition according to Claim 5 or 6 wherein the solution or suspension comprises the Fe-chelate in an amount of from 0.5 to 5% by weight and urea phosphate in an amount of from 0.5 to 5% by weight.

8. The composition according to any of Claims 5 to 7 wherein the composition is in the form of an suspension and additionally comprises methylene urea, and optionally a stabilizing agent, such as xanthane gum.

9. The composition according to any of Claims 1 to 4 in the form of a solid composition.

10. Use of a nutrient composition comprising a Fe-chelate and an acidic component wherein an aqueous solution of said composition is stable and has a pH of at most 5 for the prevention or treatment of iron deficiency in plants growing on alkaline or neutral or slightly acid soil and/or for increasing the yield of the plants.

11. The use according to Claim 10 wherein the composition is in the form of a stable acidic solution or suspension.

12. A method for the prevention or treatment of iron deficiency in plants growing on alkalme or neutral or slightly acid soil and/or for increasing the yield of the plants, comprising applying to the growing area a nutrient composition comprising a Fe-chelate and an acidic component wherein an aqueous solution of said composition is stable and has a pH of at most 5.

13. The method according to Claim 12 wherein said composition is as defined in any of claims 2 to 9.

14. The method according to Claim 11 or 12 wherein the plants are perennial wood-stemmed plants, such as grapevines, fruit trees, olive trees or berry bushes.

15. The method according to any of Claims 11 to 14 wherein the plants are growing on a calcareous soil having a pH of between 7 and 10.

16. The metliod according to any of Claims 11 to 15, comprising applying the composition in the form of a solution or suspension by injecting into the soil.