Ion exchanger fertilizers

Process for improving the plant growth with the aid of ion exchanger fertilizers, comprising adding to the growth medium weakly basic anion exchangers which are charged with anionic chelate complexes of micronutrient cations and macronutrient and micronutrient anions to the extent of at least 60% of their total capacity together with weakly acid cation exchangers charged with nutrient cations to the extent of at least 60% of their total capacity. Furthermore fertilizers comprising a mixture of weakly basic anion exchanger which are charged with anionic chelate complexes of micronutrient cations and other micronutrient and macronutrient anions to the extent of at least 60% of their total capacity and weakly acid cation exchangers which are charged with nutrient cations to the extent of at least 60% of their total capacity.

The present invention relates to a process for improving plant growth by 
using weakly basic and weakly acid ion exchangers which are charged with 
nutrients, and to ion exchanger fertilisers, which contain both weakly 
basic and weakly acid ion exchangers charged with nutrient ions, for 
supplying plants with plant nutrients on a long-term basis. 
Fertilisers based on ion exchangers charged with nutrients are known and 
have frequently been described (compare, for example, E. J. Hewitt: Sand 
and Water Culture method used in the study of plant nutrition, 
Commonwealth Agricultural Bureaux, Technical Communication No. 22, 2nd 
edition, 1966, page 61 et seq.). Complete fertilisers which are based on 
ion exchangers and contain, on a mixture of anion exchangers and cation 
exchangers, all the nutrient ions necessary for plant nutrition are of 
particular interest. Particular fertilisers of this type contain strongly 
basic or weakly basic anion exchangers which are partly, for example to 
the extent of 5%, relative to the total capacity of the anion exchanger, 
charged with anionic chelate complexes of micronutrient cations and in 
which the remainder of the exchange capacity is saturated with other 
macronutrient and micronutrient anions, and strongly acid cation 
exchangers which are charged with nutrient cations (see, for example, U.S. 
Pat. No. 3,980,462). Such fertilisers have proved particularly suitable 
when applied under normal conditions (compare Zierpflanzenbau 1978, Volume 
12, pages 476-479 and 1977 Volume 1, pages 3- 8). 
However, it has been found that under extreme conditions of application, 
the amount of nutrient released from these ion exchangers to the plants 
per unit time and unit area may be too low to fulfil the nutrient 
requirement of the plants. Such cases may lead to a deficient supply of 
nutrients to the plants and to the known consequences, for example 
depression of growth. 
The conditions of application are extreme, in particular, if, in the case 
that water with a low salt content, for example rainwater, is used for 
watering the plants, there are long diffusion paths between the ion 
exchangers and the plant roots and/or the diffusion cross-section is very 
constricted. Long diffusion paths and simultaneous constriction of the 
diffusion cross-section exist, for example, when the ion exchangers are 
used in so-called batteries (compare M. Schubert, Mehr Blumenfreude durch 
Hydrokultur (More Pleasure from Flowers through Hydroponic Culture), 6th 
edition, BLV Verlagsgesellschaft, Munich, 1979, pages 94-95). 
However, since the use of batteries provides advantages, for example ease 
of replacement of ion exchangers after exhaustion, proposals have already 
been made to use mixtures of ion exchangers fertilisers and gypsum in 
batteries to ensure more rapid discharge of the ion exchangers and thus an 
increase in the flow of nutrients (see DE-OS (German Published 
Specification) 2,819,871). This proposal is based on the assumption that 
gypsum is dissolved only according to its solubility, even in the presence 
of ion exchangers, and addition of a large amount of gypsum thus 
represents a suitable store of salt which dissolves only slowly and thus 
is suitable for promoting the release of the nutrients from the ion 
exchangers over a long period of time. This assumption, however, is based 
on an error, since it is known that sparingly soluble salts, for example 
gypsum, are rapidly dissolved completely by ion exchangers (see F. 
Helfferich, Ion Exchange, McGraw-Hill Book Comp., New York, 1962, pages 
226-229 and 295-299), equivalent amounts of readily soluble salts passing 
into solution. In the present case, these are the nutrient salts with 
which the ion exchangers are charged. It is thus not possible for slow 
release of the nutrients from ion exchangers charged with nutrients to be 
achieved by adding gypsum. Rather, the addition of gypsum has the effect 
of a sudden sharp rise in the nutrient concentration in the solution and a 
rapid discharge of the ion exchangers which corresponds to the amount of 
gypsum used. The desired slow release of the nutrient ions is not achieved 
by adding gypsum. Moreover, salt damage may occur to plants which are 
sensitive to salts, such as orchids, bromelias, azaleas, ferns and young 
plants generally, as a result of rapid release of the nutrient salts (see 
F. Penningsfeld et al.: Hydrokultur und Torfkultur (Hydroponic Culture and 
Peat Culture), pages 40-42, Ulmer Verlag, Stuttgart, 1966). 
It has now been found that release of the nutrient ions matched to the 
nutrient requirement of the plants can be achieved under extreme 
conditions of application by a procedure in which the weakly basic anion 
exchangers charged with anionic chelate complexes of micronutrient cations 
and macronutrient and micronutrient anions (a) are charged to the extent 
of at least 60%, preferably to the extent of at least 80%, of their total 
capacity and (b) are used together with weakly acid cation exchangers, 
which are likewise charged to the extent of at least 60%, preferably to 
the extent of at least 80%, of their total capacity. 
As a result of this conjoint use of highly charged weakly basic and weakly 
acid ion exchangers charged with nutrient ions, the release of the 
nutrient salts no longer decreases as the salt content of the aqueous 
medium surrounding them decreases, but increases. That is to say, in 
contrast to the use of the known fertilisers based on ion exchangers, for 
example the fertilisers described in U.S. Pat. No. 3,980,462, when highly 
charged weakly basic and weakly acid ion exchangers are used together, the 
more nutrient salts are released to the aqueous medium surrounding them 
the lower the salt concentration thereof is. As a result of this property, 
conjoint use of weakly basic and weakly acid ion exchangers charged with 
nutrients ensures that the plants are sufficiently supplied with 
nutrients, even if water with a low salt content is used for watering the 
plants, if containers with a restricted diffusion cross-section are used, 
or at the end of the period of fertiliser application, when the salt 
content of the nutrient solution has already fallen as a result of the 
salts being used up. 
Mixtures of weakly basic and weakly acid ion exchangers charged with 
nutrient ions together with strongly basic and strongly acid ion 
exchangers charged with nutrient ions have already been used as 
fertilisers (see G. Rivoira, Rivista di Agronomia, Bologna 2 (1968), 
Volume 3/4, pages 207 to 211). The weakly basic anion exchangers and 
weakly acid cation exchangers used in these four-component mixtures were, 
however, only partly charged, to the extent of about 20% of their total 
capacity, as can be seen from the charging method described. These 
mixtures thus exhibited only the known release of nutrient ions from the 
ion exchangers, which increases as the salt content of the surrounding 
aqueous medium increases. 
Experiments with mixtures of weakly acid and strongly basic ion exchangers 
charged with nutrients are described in Natur, Volume 198 (1963), pages 
1,328-1,329. These mixtures also only exhibit the usual release of 
nutrient salts, which decreases as the salt content of the aqueous medium 
surrounding them decreases. 
The conjoint use, according to the invention, of the weakly basic and 
weakly acid ion exchangers highly charged with nutrient ions can be 
effected in various ways. Thus, the ion exchangers can be employed 
individually, that is to say separately from one another, or in the form 
of mixtures. It is preferable to use mixtures. 
The invention thus furthermore relates to ion exchanger fertilisers 
consisting of mixtures of weakly basic anion exchangers charged with 
anionic chelate complexes of micronutrient cations and other micronutrient 
and macronutrient anions, and cation exchangers charged with nutrient 
cations, which are characterised in that they contain mixtures of weakly 
basic anion exchangers which are charged to the extent of at least 60%, 
preferably to the extent of at least 80%, of their total capacity with 
anionic chelate complexes of micronutrient cations and other micronutrient 
and macronutrient anions, and weakly acid cation exchangers which are 
charged to the extent of at least 60%, preferably to the extent of at 
least 80%, of their total capacity with nutrient cations. 
The weakly basic anion exchangers which are charged with anionic chelate 
complexes of micronutrient cations and other macronutrient and 
micronutrient anions and which are to be used in the process according to 
the invention or in the fertilisers according to the invention are anion 
exchangers in which the exchange capacity (=total capacity=content of 
weakly basic groups) is saturated with anionic chelate complexes of 
micronutrient cations to the extent of 0.25 to 25%, preferably to the 
extent of 0.5 to 15%, and their remaining exchange capacity is saturated 
with macronutrient anions and other micronutrient anions. 
The ratio in which the highly charged weakly basic and weakly acid ion 
exchangers are used in the process according to the invention or in the 
fertilisers according to the invention are applied can vary within wide 
limits and depends, inter alia, on the desired pH value in the substrate. 
The amount of weakly acid groups is preferably 10 to 90%, and 
preferentially 10 to 50%, relative to the sum of weakly basic and weakly 
acid groups. 
All the weakly basic and weakly acid synthetic resin ion exchangers are 
suitable for the process according to the invention and the fertilisers 
according to the invention. The ion exchangers can be polymerisation 
resins or condensation resins. They can have a gel-type or macroporous 
structure. 
By weakly basic anion exchangers, there are to be understood the known 
anion exchangers containing primary, secondary and tertiary amino groups, 
and by weakly acid cation exchangers there are to be understood the known 
cation exchangers containing carboxyl groups, phosphinic acid groups and 
phenolic hydroxyl groups, and also the weakly acid cation exchangers which 
contain aminocarboxylic acid groups and form chelate complexes. These 
weakly basic anion exchangers and weakly acid cation exchangers and their 
preparation are described, for example, in F. Helfferich, loc. cit., pages 
26 to 71 and Ullmanns Enzyklopadie der technischen Chemie (Ullmanns 
Encyclopaedia of Industrial Chemistry), 4th edition, Volume 13, 1977, 
pages 295-309. 
In particular, weakly basic anion exchangers and weakly acid cation 
exchangers which can be employed for the so-called Sirotherm process may 
also be used. The selection criteria and the preparation of these ion 
exchangers are described, for example, in: Aust. J. Chem. 19 (1966) pages 
561-587, 589-608 and 765-789; and in U.S. Pat. Nos. 3,645,922, 3,888,928 
and 3,619,394. 
The weakly basic anion exchangers based on crosslinked polyacrylamides and 
crosslinked polyvinylbenzylamines and the weakly acid cation exchangers 
based on crosslinked poly(meth)acrylic acid have proved particularly 
suitable. 
The fertilisers according to the invention can contain all the essential 
macronutrients and micronutrients, anionic nutrients, such as nitrate, 
phosphate, sulphate, molybdate and borate, being bonded to anion 
exchangers and cationic nutrients, such as potassium, ammonium, calcium 
and magnesium, being bonded to cation exchangers. Micronutrients such as 
iron, manganese, copper, chromium, cobalt and zinc are bonded to weakly 
basic anion exchangers in the form of anionic chelate complexes. The 
fertilisers according to the invention preferably contain the 
macronutrients nitrogen, phosphorus and potassium, which are of particular 
importance for healthy plant development, and the micronutrients boron, as 
borate, molybdenum, as molybdate and iron, copper, manganese and zinc, as 
anionic chelate complexes. Weakly basic anion exchangers charged with such 
anionic chelate complexes are described, for example, in U.S. Pat. No. 
3,980,462. The exchangers can contain nitrogen as nitrate nitrogen and 
ammonium nitrogen in a molar ratio of 90:10 to 50:50, and phosphorus as 
dihydrogen phosphate or hydrogen phosphate. 
The proportions of individual nutrients used in the fertilisers according 
to the invention can vary within wide limits and are advantageously 
matched to the particular nutrient requirements of the various species of 
plants. Proportions which are particularly suitable are described in the 
literature (see U.S. Pat. Nos. 3,082,074 and 3,980,462; and E. J. Hewitt: 
Sand and Water Culture method used in the study of plant nutrition, 
Commonwealth Agricultural Bureaux, Technical Communication No. 22, 2nd 
edition, 1966, page 61 et seq.). 
The high charge of the weakly acid and weakly basic ion exchangers with the 
nutrient ions which is required according to the invention can be effected 
in various ways: thus, the weakly acid cation exchangers can be charged by 
stirring the H.sup.+ form with an approximately 10% strength aqueous 
solution of the free base containing the desired cation, for example an 
aqueous solution of potassium hydroxide, ammonium hydroxide, calcium oxide 
or magnesium oxide, until equilibrium is established. The weakly basic 
anion exchangers are advantageously treated, in the OH.sup..crclbar. form, 
first with a 0.1-5% strength aqueous solution of the anionic chelate 
complexes of the micronutrient cations, then with a 0.01-1% strength 
aqueous solution containing the micronutrient anions, and finally with an 
approximately 10% strength solution of the free acid containing the 
desired macronutrient anion, for example nitric acid, sulphuric acid or 
phosphoric acid, or a mixture of these acids, until equilibrium is 
established. It is also possible first to stir the OH.sup..crclbar. form 
of the weakly basic anion exchangers with a 0.1 to 5% strength aqueous 
solution of a chelating agent, which is in the form of the free acid, and 
then to add a 0.1 to 5% strength aqueous solution of one or more salts of 
micronutrient cations to this mixture. After equilibrium is established, 
the anion exchanger which has thus been charged with the anionic chelate 
complexes is further charged, as indicated above, with micronutrient 
anions and macronutrient anions. 
The rate of charging can be increased by adding a small amount of a salt, 
for example potassium nitrate. After the charging operation, the ion 
exchangers are separated off from the aqueous solution by filtration or 
centrifugation and are dried separately. The charged ion exchangers can be 
employed individually, in combination, or as a mixture. 
However, it is also possible to charge the weakly acid and weakly basic ion 
exchangers simultaneously, by charging a mixture of the weakly basic anion 
exchanger in the OH.sup.- form and the weakly acid cation exchanger in the 
H.sup.+ form in a 0.5 to 3 molar fertiliser salt solution with a content 
of anionic chelate complexes of micronutrient cations of 0.01 to 1 mol/l 
at temperatures of 0.degree. to 70.degree. C., preferably 5.degree. to 
25.degree. C., whilst stirring. In certain circumstances it may also be 
advantageous first to stir the ion exchanger mixture with an aqueous 
solution of the anionic chelate complexes of the micronutrient cations, 
until these have been adsorbed onto the anion exchanger, and then to 
continue the charging operation by adding further fertiliser salts. If the 
ion exchanger mixture contains an excess of weakly basic or weakly acid 
groups, this excess is saturated, before or after the charging with 
fertiliser salts, by adding acid, for example nitric acid, or base, for 
example potassium hydroxide. 
The ion exchanger mixture is then again isolated by filtration or 
centrifugation. Whilst a mixture of the moist ion exchanger resins charged 
with nutrients, which can also be dried if required, is obtained by this 
process, the individual components, which can be employed individually in 
combination, or as a mixture, are obtained by the former process. 
The combinations, according to the invention, of highly charged weakly 
basic anion exchangers and weakly acid cation exchangers can be used 
together with strongly basic anion exchangers charged with nutrient ions 
and/or strongly acid cation exchangers charged with nutrient cations, 
without the property of the combinations of highly charged weakly basic 
anion exchangers and weakly acid cation exchangers of releasing an 
increased amount of nutrient salts as the salt content of the surrounding 
aqueous medium decreases being impaired by these additional components. 
The strongly acid cation exchangers which can additionally be used may be 
charged with cationic nutrients such as potassium, ammonium, calcium or 
magnesium, and the strongly basic anion exchangers may be charged with 
anionic nutrients such as nitrate, phosphate, sulphate, borate or 
molybdate. 
The ratio of strong ion exchangers to weak ion exchangers can vary within 
wide limits. The proportion of the total cation exchange capacity which is 
made up of strongly acid cation exchangers can be up to 80%, preferably up 
to 50%. The proportion of total anion exchange capacity which is made up 
of strongly basic anion exchangers can likewise be up to 80%, preferably 
up to 50%. 
The general sense of these statements applies in the same way to the 
proportions of strongly basic or strongly acid groups when anion 
exchangers which, in addition to weakly basic groups, also contain 
strongly basic groups, or cation exchangers which, in addition to weakly 
acid groups, also contain strongly acid groups, are used. The addition of 
customary strongly acid cation exchangers charged with nutrients is of 
particular interest. 
The process according to the invention and the fertilisers according to the 
invention are particularly advantageously applied in hydroponic culture, 
especially when water with a low salt content is used for watering the 
plants and the ion exchanger fertiliser is used in replaceable nutrient 
batteries in which the diffusion cross-section for the nutrients is 
restricted at the outlet by perforated plates or slotted plates, fleeces 
or films. The process according to the invention ensures that the plants 
are well-supplied with nutrients over a long period, even under extreme 
conditions of application. 
The conjoint use, according to the invention, of the highly charged weakly 
basic and weakly acid ion exchangers can be effected in various ways. It 
is thus possible, for example, to accommodate the two components by 
themselves in separate chambers of a two-chamber battery or in two 
individual batteries; however, it is also possible to accommodate them 
together, after mixing, in a battery with only one chamber. 
The process according to the invention and the fertilisers according to the 
invention can, however, also be applied in the most diverse naturally 
occurring and synthetic substrates in which plants grow. 
Application is effected by the methods customary in agriculture and 
horticulture: for example, the components of the fertilisers according to 
the invention can, individually in combination or as a mixture, be mixed 
with the naturally occurring or synthetic substrate or be incorporated in 
the soil by digging or ploughing. They can furthermore be scattered over 
the plants or their environment as a top dressing. 
The fertilisers according to the invention can be used either as such or, 
if appropriate, as a mixture with other fertilisers, extenders, plant 
protection agents and/or growth regulators. 
The fertilisers according to the invention can be in the form of fine 
beads, or larger balls, in the form of granules, in pulverulent form, in 
the form of lumps or in the form of mouldings. 
The amounts of highly charged weakly basic and weakly acid ion exchangers 
employed, when used conjointly, in the process according to the invention 
and the amounts of ion exchanger mixtures, charged with nutrients, 
according to the invention which are employed can vary within relatively 
wide limits. They essentially depend on the particular nutrient 
requirement of the plants. In general, the amounts applied are between 
0.001 and 0.1 l of ion exchanger per liter of growth medium preferably 
between 0.002 and 0.05 l per liter of growth medium. 
The process according to the invention and the fertilisers according to the 
invention are suitable for uniformly supplying useful plants and 
ornamental plants on a long-term basis. The useful plants include, for 
example, herbs for cooking, such as parsley (Petroselinum sativum), chives 
(Allium schoenoprasum) and marjoram (Origanum majorana), vegetables, such 
as lettuce (Lactuca sativa), radishes (Raphanus sativus), cucumbers 
(Cucumis sativus) and tomatoes (Solanum lycopersicum); small fruits, such 
as strawberries (Fragaria speciosa), currants (Ribes rubrum petracum), 
gooseberries (Ribes grossularia) and wine (Vitris vinifera); pineapples 
(Ananas sativus); citrus varieties; cherries (Prunus); and peaches (Prunus 
persica). 
Examples of ornamental plants which may be mentioned are: aechmea (Aechmea 
fasciata), ivy (Hedera helix), croton (Codiaeum variegatum), palms 
(Chamaedorea elegans), philodendrons (Philodendron red emerald; 
Philodendron scandens; Monstera deliciosa), euphorbias (Euphorbia 
pulcherrima), ferns (Adiantum scutum roseum), rubber plants (Ficus 
elastica Decora, Ficus robusta, Ficus diversifolia and Ficus benjamina), 
aphelandra (Aphelandra squarrosa dania), maranta (Maranta makoyana), 
chrysanthemums (Yellow Delaware), anthurias (Anthurium scherzerianum), 
ericaceae (Erica gracilis), azaleas (Rhododendron simsii), dieffenbachias 
(Dieffenbachia amoena; Tropic white), dracaenas (Dracaena terminalis and 
Dracaena deremensis), hibiscus (Hibiscus rosasinensis), lady's slipper 
(Cypripedium), guzmania (Guzmania minor), pachystachys (Pachystachys), 
peperonia (Peperonia glabella), staghorn ferns (Platycerium alcicorne), 
scindapsus (Scindapsus aureus), spatiphyllum (Spatiphyllum wallisii) and 
vriesea (Vriesea splendens).

The degree of charging (in %) given in the following examples relates to 
the total capacity of the ion exchanger resin in question. 
EXAMPLE 1 
To prepare an ion exchanger fertiliser containing nitrogen, sulphur and 
iron, 500 ml of each of the nutrient-charged ion exchanger resins A and B 
described below are mixed. 
The nutrient content of the mixture is: 
nitrogen: 19.5 mg/ml 
nitrate nitrogen in the above: 6 mg/ml 
sulphur: 3 mg/ml 
iron: 5 mg/ml 
The content of weakly acid groups, relative to the total amount of weakly 
acid groups and weakly basic groups, is 52%. 
The nutrient-charged ion exchanger resins A and B used were obtained as 
follows: 
Resin A 
500 ml of a weakly basic anion exchanger in the free base form (content of 
weakly basic groups: 2.34 mols/l), prepared by aminomethylation of a 
styrene bead polymer which has been crosslinked with 8% of divinylbenzene 
and rendered macroporous by adding 60% (relative to the monomer mixture) 
of a C.sub.12 -hydrocarbon mixture, were suspended in 1,000 ml of 
completely demineralised water, and, at 20.degree. to 25.degree. C., 
whilst stirring, 125 mmols of ethylenediamine-tetraacetic acid and 125 
mmols of iron-II sulphate were added successively, and 1.5 N nitric acid 
was then added in portions until a constant pH value of 4.3 had been 
established in the aqueous phase. The nitric acid consumption was 360 ml. 
The ion exchange resin charged in this way was filtered off. Yield: 640 
ml. 
Content of nitrate nitrogen: 12 mg/ml; 
Degree of charging: 47%; 
Content of iron: 10 mg/ml; 
Degree of charging: about 10%; 
Content of sulphur: 6 mg/ml; 
Degree of charging: 21%. 
Resin B 
500 ml of a weakly acid cation exchanger in the acid form (content of 
weakly acid groups: 3.2 mols/l), prepared by alkaline saponification of a 
methacrylic acid methyl ester bead polymer which had been crosslinked with 
5% of divinylbenzene and rendered macroporous by the addition of 30% of 
isooctane (relative to the monomer mixture), were suspended in a solution 
of 5 g of ammonium chloride in 1,000 ml of completely demineralised water, 
and 375 ml of approximately 10% strength ammonia solution were added at 
20.degree. to 25.degree. C. in the course of 2 hours, whilst stirring. 
After stirring the mixture for 16 hours, a pH value of 9.9 had been 
established in the aqueous phase. The charged cation exchange resin was 
then separated off from the aqueous phase. Yield: 810 ml, content of 
ammonium nitrogen: 27 mg/ml; degree of charging: 98%. 
EXAMPLE 2 
To prepare an ion exchanger fertiliser containing the main nutrients 
nitrogen, phosphorus and potassium and the micronutrients iron and 
manganese, the nutrient-charged exchanger resins A, B, C, D and E 
described below are mixed in the amount given in the following table. A 
fertiliser with a nutrient content which can likewise be seen from the 
table is obtained. 
TABLE 
__________________________________________________________________________ 
Amount of ion-exchanging groups 
Nutrient 
(mmols/100 g of mixture) content 
weakly 
strongly 
weakly 
strongly g/100 g 
Resin 
Amount g 
basic 
basic 
acid 
acid Nutrient of mixture 
__________________________________________________________________________ 
A 89 330 -- -- -- nitrate nitrogen 
2.9 
B 16 41 8 -- -- phosphorus 
0.7 
manganese 0.1 
C 8 -- -- 60 -- potassium 1.5 
D 10 -- -- 87 -- ammonium nitrogen 
0.7 
E 16 -- -- -- 56 potassium 1.5 
__________________________________________________________________________ 
The content of the mixture is as follows: 28% of weakly acid groups, 
relative to the total amount of weakly acid and weakly basic groups; 28% 
of strongly acid groups, relative to the total amount of acid groups; and 
2% of strongly basic groups, relative to the total amount of basic groups. 
The nutrient-charged ion exchange resins A to E used were obtained as 
follows: 
Resin A 
500 ml of a weakly basic anion exchanger in the free base form (content of 
weakly basic groups: 3 mols/l), prepared by aminomethylation of a styrene 
bead polymer which had been crosslinked with 4% of divinylbenzne, were 
suspended in 500 ml of completely demineralised water, and 93 ml of nitric 
acid (about 65% strength) and 225 mmols of the iron-III chelate complex of 
ethylenediamine-tetraacetic acid were added at 20.degree. to 25.degree. 
C., whilst stirring. After equilibrium had been established, the pH value 
in the aqueous phase was 4.5. The anion exchange resin thus charged was 
separated off from the aqueous solution by filtration and dried in air at 
room temperature for 20 hours. Yield: 404 g of a free-flowing product. 
Content of nitrate nitrogen: 45 mg/g; 
Degree of charging: 87%; 
Content of iron: 9 mg/g; 
Degree of charging: about 5%; 
Water content: 20% by weight. 
Resin B 
500 ml of a moderately basic anion exchanger in the OH.sup.- form (content 
of weakly basic groups: 1.27 mols/l, content of strongly basic groups: 
0.25 mol/l), prepared by aminolysis of an acrylic acid methyl ester bead 
polymer, which had been crosslinked with 5% of divinylbenzene and 3% of 
1,7-octadiene, with N,N-dimethylaminopropylamine and subsequent partial 
quaternisation with methyl chloride, were suspended in 500 ml of 
completely demineralised water, and 57 g of phosphoric acid (about 85% 
strength) and 75 mmols of the manganese-II chelate complex of 
ethylenediamine-tetraacetic acid were added at 20.degree. to 25.degree. 
C., whilst stirring. After subsequently stirring the mixture for 16 hours, 
the pH value of the aqueous phase was 4.6. The anion exchange resin thus 
charged was filtered off and dried in air at room temperature for 72 
hours. Yield: 246 g of a free-flowing product. 
Content of phosphorus: 62 mg/g; 
Degree of charging: about 90%; 
Content of manganese: 9 mg/g; 
Degree of charging: about 6%; 
Water content: 22% by weight. 
Resin C 
780 ml of a weakly acid cation exchanger in the acid form (content of 
weakly acid groups: 4.6 mols/l), prepared by acid hydrolysis of an 
acrylonitrile bead polymer which had been crosslinked with 7% of 
divinylbenzene and 2% of 1,7-octadiene, were suspended in 1 l of 0.03 N 
potassium chloride solution, and 3.4 mols of potassium hydroxide (in the 
form of a 5 molar aqueous solution) were added in portions at 20.degree. 
to 25.degree. C., whilst stirring. After subsequently stirring the mixture 
for 12 hours, a pH value of 9 had been established in the aqueous phase. 
The charged cation exchange resin was filtered off and partially dried at 
70.degree. C. in vacuo (130 mbars). Yield: 475 g of a free-flowing 
product. `Content of potassium: 267 mg/g; 
Degree of charging: 90%; 
Water content: 5.9% by weight. 
Resin D 
750 ml of the weakly acid cation exchanger in the acid form used for the 
preparation of resin C in Example 2 were suspended in 1 l of 0.05 N 
ammonium chloride solution, and 270 ml of aqueous ammonia solution (about 
23% strength) were added at room temperature in the course of 4 hours, 
whilst stirring. After subsequently stirring the mixture for 12 hours, a 
pH value of 9 had been established in the aqueous phase. The cation 
exchange resin thus charged was isolated by filtration and partially dried 
at 90.degree. C. in vacuo (130 mbars). Yield: 395 g of a free-flowing 
product. 
Content of ammonium nitrogen: 101 mg/g; 
Degree of charging: 83%; 
Water content: 9.4% by weight. 
Resin E 
550 ml of a commercially available strongly acid cation exchanger resin on 
a styrene bead polymer, crosslinked with 8% of divinylbenzene, in the acid 
form (content of strongly acid groups: 2.1 mols/l) were charged with 
potassium in a filter tube by passing over a 2.5% strength potassium 
chloride solution until the runnings from the filter tube were free from 
acid. The exchanger was then washed until free from chloride and 
subsequently dried in air at room temperature for 24 hours. Yield: 345 g 
of a free-flowing product. 
Content of potassium: 129 mg/g; 
Water content: 24% by weight. 
EXAMPLE 3 
To prepare an ion exchanger fertiliser containing the main nutrients 
nitrogen and potassium and the micronutrient iron, 50 ml of the weakly 
basic anion exchanger used for the preparation of resin A in Example 2 
(content of weakly basic groups: 150 mmols) and 33 ml of the weakly acid 
cation exchanger used for the preparation of resin C in Example 2 (content 
of weakly acid groups: 150 mmols) are introduced into a solution of 1.5 
mols of potassium nitrate and 6 mmols of the iron-III chelate complex of 
ethylenediamine-di-(o-hydroxyphenyl)-acetic acid in 500 ml of completely 
demineralised water. The suspension was stirred at room temperature until 
the ion exchanger was completely charged. After stirring the suspension 
for 120 hours, a constant specific conductivity of 145 mS/cm (20.degree. 
C.) and a pH value of 7.5 had been established in the aqueous phase. The 
ion exchanger mixture thus charged was filtered off, rinsed with methanol 
and then partially dried at 40.degree. C. Yield: 62 g of a free-flowing 
product. 
Content of nitrate nitrogen: 33 mg/g; 
Degree of charging: 97%; 
Content of iron: 4 mg/g; 
Degree of charging: 3%; 
Content of potassium: 93 mg/g; 
Degree of charging: 98%; 
Water content: 6% by weight. 
EXAMPLE 4 
To prepare an ion exchanger fertiliser which contains the main nutrients 
nitrogen, phosphorus, potassium and sulphur and the micronutrients, boron, 
iron, copper, manganese, molybdenum and zinc, and which is particularly 
suitable as a complete fertiliser for hydroponic culture of plants using 
water with a low salt content, 490 ml of the moist, weakly basic anion 
exchanger A which is charged with nitrate, phosphate, sulphate and the 
micronutrients and which is described below, and 150 ml of the weakly acid 
cation exchanger B which is charged with potassium and ammonium and is 
described below, are mixed, and the mixture is partially dried at 
60.degree. C. in vacuo (24 mbars) in a rotary evaporator. Yield: 315 g of 
a free-flowing product. 
Water content: 7% by weight. 
The nutrient content of the fertiliser per 100 g is as follows: 
Nitrate nitrogen: 3.5 g 
Ammonium nitrogen: 0.7 g 
Phosphorus: 0.8 g 
Potassium: 3.0 g 
Boron: 2 mg 
Iron: 102 mg 
Copper: 1 mg 
Manganese: 7 mg 
Molybdenum: 7 mg 
Zinc: 1 mg 
Sulphur: 1 mg 
Weakly basic groups: 324 mmols 
Weakly acid groups: 135 mmols (=29%, relative to the total content of 
weakly basic groups and weakly acid groups in the fertiliser). 
The nutrient-charged resins A and B used were obtained as follows: 
Resin A 
1,000 ml of the weakly basic anion exchanger in the free base form used for 
the preparation of resin A in Example 2 were suspended in 1,000 ml of 
completely demineralised water, and 5.96 g of ethylenediaminetetraacetic 
acid, 27 g of phosphoric acid (about 85% strength) 0.57 g of Na.sub.2 
B.sub.4 O.sub.7.10H.sub.2 O, 0.11 g of (NH.sub.4).sub.6 Mo.sub.7 
O.sub.24.4H.sub.2 O, 5 g of FeSO.sub.4.7 H.sub.2 O, 0.3 g of 
MnSO.sub.4.H.sub.2 O, 0.045 g of CuSO.sub.4.5H.sub.2 O, 0.05 g of 
ZnSO.sub.4.7H.sub.2 O and 250 g of nitric acid (about 65% strength) were 
added successively at room temperature in the course of 3 hours, whilst 
stirring. 
After subsequently stirring the mixture for 20 hours, the pH value of the 
aqueous phase was 4.5. The anion exchange resin thus charged was separated 
off from the aqueous phase by filtration. Yield: 1,440 ml of moist 
product. 
Content of nitrate nitrogen: 22.6 mg/ml; 
Degree of charging: 78%; 
Content of phosphorus: 5.0 mg/ml; 
Degree of charging: about 12%; 
Content of sulphur: 0.4 mg/ml; 
Degree of charging: about 1%; 
Total content of anionically chelated nutrient cations (iron, copper, 
manganese and zinc): 0.7 mg/ml; 
Degree of charging: about 0.7%; 
Total content of borate and molybdate: 0.06 mg/ml; 
Degree of charging: about 0.2%. 
Resin B 
1,000 ml of the weakly acid cation exchanger in the acid form used for the 
preparation of resin C in Example 2 were suspended in a solution of 3.75 g 
of potassium chloride in 1 l of completely demineralised water, and 183 g 
of potassium hydroxide (in the form of an 84% strength aqueous solution) 
were added at 20.degree. to 25.degree. C. in the course of 25 minutes, 
whilst stirring and cooling. After subsequently stirring the mixture for 3 
hours, a pH value of 7.3 had been established in the aqueous phase. 135 ml 
of aqueous ammonia solution (about 25% strength) were then added dropwise 
at the above temperature in the course of 2.75 hours. During this 
addition, the pH value rose to 9.4. After subsequently stirring the 
mixture for 16 hours, the pH value was 9.2. The weakly acid cation 
exchange resin thus charged was filtered off. Yield: 1,620 ml of moist 
cation exchange resin. 
Content of potassium: 64 mg/ml; 
Degree of charging: 58%; 
Content of ammonium nitrogen: 15 mg/ml; 
Degree of charging: 38%. 
EXAMPLE 5 (COMISON EXAMPLE) 
To prepare an ion exchanger fertiliser containing the main nutrients 
nitrogen, phosphorus, potassium and sulphur and the micronutrients boron, 
iron, copper, manganese, molybdenum and zinc using a weakly basic ion 
exchanger and a strongly acid ion exchanger, resin A used in Example 4 is 
first charged, as described. However, the resin is not separated off from 
the aqueous phase, but after the charging operation, 570 ml of the 
strongly acid cation exchanger used for the preparation of resin E in 
Example 2, 51.5 g of potassium hydroxide (85% strength) and 35 g of 
ammonia solution (about 25% strength) are successively introduced, at room 
temperature in the course of 2 hours, whilst stirring, into the suspension 
of the weakly basic anion exchanger which has been charged with nitrate, 
phosphate, sulphate and the micronutrients. 
After subsequently stirring the mixture for 16 hours, the pH value of the 
aqueous phase was 4.6. The ion exchanger mixture charged with nutrients 
was separated off from the aqueous phase and partially dried at 90.degree. 
C. in vacuo (120 mbars) for 24 hours. Yield: 1,040 g of a free-flowing 
product. 
Water content: 6% by weight. 
Nutrient content of the fertiliser mixture per 100 g of mixture: 
Nitrate nitrogen: 3.2 g 
Ammonium nitrogen: 0.6 g 
Phosphorus: 0.7 g 
Potassium: 2.8 g 
Boron: 2 mg 
Iron: 91 mg 
Copper: 1 mg 
Manganese: 6 mg 
Molybdenum: 7 mg 
Zinc: 1 mg 
Sulphur: 1 mg 
Weakly basic groups: 288 mmols 
Strongly acid groups: 121 mmols 
EXAMPLE 6 
Fertilising test using ornamental plants in a hydroponic culture 
Comparative fertilising tests were carried out on ornamental plants in a 
hydroponic culture using the fertiliser of Example 4 according to the 
invention and the fertiliser of Example 5 (comparison example). The 
fertilisers were applied in commercially available nutrient batteries 
which were in the form of small boxes (compare M. Schubert, loc. cit., 
diagram on page 94) and had a restricted diffusion cross-section 
(dimensions of the plastic batteries: 45.times.45.times.20 mm; top and 
bottom with 13 slit rows each; slit width: 0.05 to 0.3 mm; total slit 
length per row: 28 mm). 
The amounts of fertiliser employed per battery and the amounts of nutrient 
contained therein are given in Table 1. 
TABLE 1 
______________________________________ 
Amounts of fertiliser per battery 
Fertiliser 
according to 
Fertiliser 
Example 5 
according 
(comparison 
Example 4 
example) 
______________________________________ 
Amount (g) 9 10 
Nitrate nitrogen (mg) 
315 320 
Ammonium nitrogen (mg) 
63 60 
Phosphorus (mg) 72 70 
Potassium (mg) 270 280 
Boron (mg) 0.2 0.2 
Iron (mg) 9 9 
Copper (mg) 0.1 0.1 
Manganese (mg) 0.6 0.6 
Molybdenum (mg) 0.6 0.7 
Zinc (mg) 0.1 0.1 
Sulphur (mg) 0.1 0.1 
______________________________________ 
The plants were grown in commercially available individual containers which 
have a water reservoir and in which the nutrient battery is located 
underneath the plant pot (growing pot). Relatively long diffusion paths 
for the nutrients thus result. Expanded clay was used as the plant 
substrate. Drinking water which had a low salt content and a specific 
conductivity of 100 .mu.S/cm at 20.degree. C. was used as the water for 
the plants. 
The experiments were carried out on 4 ornamental plant varieties: Ficus 
benjamina, Rhaphidophora aurea, Dieffenbachia amoena "Tropic White" and 
Dracaena massangeana. 
4 Plants were used for each experimental variant. As soon as the 
fertilising action of the fertilisers was exhausted, the old batteries 
were replaced by new ones. The total experimental period (growing time) 
varied between 229 and 345 days, depending on the plant variety, using 2 
nutrient batteries per plant, compare Table 2. 
At the end of the experiment, the plants were evaluated from general 
horticultural viewpoints--such as quality, leaf colour and habit--and the 
additional growth was determined (end weight minus initial weight). In the 
case of the rhaphidophora, the additional growth is obtained from the 
weight of the tendrils cut off. In addition, the length of leaves and the 
number of leaves were determined in the case of the dieffenbachia and 
dracaena, and the number of new shoots was determined in the case of the 
rhaphidophora. Table 2 gives the results obtained, as average values for 
each plant variety. 
TABLE 2 
______________________________________ 
Plant growth and plant evaluation 
Growth values or 
evaluation rating.sup.(1) 
Fertiliser 
according to 
Growing Fertiliser Example 5 
Plant variety time according to 
(comparison 
Growth Parameters 
[days] Example 4 example) 
______________________________________ 
Ficus benjamina 229 
Evaluation 2.5 3.5 
Additional growth: 
g 176 142 
% 124 100 
Rhaphidophora 266 
Evaluation 2 4 
Tendrils: g 109 86 
% 127 100 
Number of shoots 6.75 5.25 
Dieffenbachia 288 
Evaluation 2 3 
Additional growth: 
g 230 170 
% 135 100 
Length of leaves: 
cm 29.0 26.2 
% 110 100 
Dracaena 345 
Evaluation 2 3.5 
Additional growth: 
g 104 72 
% 144 100 
Number of leaves 15 11 
______________________________________ 
.sup.(1) Evaluation ratings 1 to 5; rating 1 corresponds to a very good 
plant quality 
It can be seen, from Table 2, that average evaluation ratings of about 2 
were found for all plant varieties at the end of the growing time when the 
fertiliser, according to the invention, of Example 4 was used. This 
corresponds to a good plant quality. In contrast, all the plants from the 
comparison experiments with the fertiliser according to Example 5 
(comparison example) were evaluated as 1 to 2 points poorer. It can also 
be seen from Table 2 that the plants supplied with the fertiliser 
according to the invention exhibited a considerably better growth. If the 
value found for the additional growth of the plants supplied with the 
fertiliser according to Example 5 (comparison example) is set at 100% in 
each case, the results, by comparison, for the plants supplied with the 
fertiliser according to the invention are 124% in the case of Ficus 
benjamina, 127% in the case of Rhaphidophora, 135% in the case of 
Dieffenbachia amoena and 144% in the case of Dracaena massangeana. The 
better growth with the fertiliser according to the invention can also be 
seen from the increased number of shoots in the case of the rhaphidophora, 
the larger leaves (leaf length) in the case of the dieffenbachia and the 
higher number of leaves in the case of Dracaena massangeana. 
Comparable experimental results were obtained where resin A and resin B 
from Example 4 were employed, separately from one another, in a 2-chamber 
battery instead of in a 1-chamber nutrient battery, or each resin was 
filled into a fleece bag by itself and the fleece bags were suspended in 
the aqueous phase. 
EXAMPLE 7 
To prepare an ion exchanger fertiliser containing the main nutrients 
nitrogen, phosphorus, potassium and calcium and the micronutrients iron 
and manganese, the nutrient-charged exchange resins A, B and C described 
in Example 2 and exchange resin D described below are mixed in the amount 
given in the following table. A fertiliser with a nutrient content which 
can likewise be seen from the table is obtained. 
TABLE 
______________________________________ 
Amount of ion- 
exchanging groups Nutrient 
A- [mmols/100 g of mixture] [g/100 g 
Res- mount weakly strongly 
weakly of 
in [g] basic basic acid Nutrient 
mixture] 
______________________________________ 
A 44 163 -- -- nitrate 3.1 
nitrogen 
iron 0.6 
B 8 20 4 -- phosphorus 
0.8 
manganese 
0.1 
C 8 -- -- 60 potassium 
3.3 
D 4 -- -- 26 calcium 0.8 
______________________________________ 
The content of weakly acid groups in the mixture is 32% (relative to the 
total amount of weakly acid groups and weakly basic groups). 
Resin D 
420 ml of the weakly acid cation exchanger in the acid form used for the 
preparation of resin C in Example 2 were suspended in 300 ml of tapwater, 
and 75 g of technical-grade calcium hydroxide (95% strength) were added at 
room temperature, whilst stirring. 
After subsequently stirring the mixture for 20 hours, the pH value in the 
aqueous phase was 9.7. The cation exchange resin thus charged was rinsed 
in a filter column until the runnings were clear and then isolated by 
filtration and dried in air at room temperature for 48 hours. Yield: 293 g 
of a free-flowing product. 
Content of calcium: 125 mg/g 
Degree of charging: 95% 
Water content: 23%.