GB2045056A

GB2045056A - Coating seeds

Info

Publication number: GB2045056A
Application number: GB7911582A
Authority: GB
Original assignee: Saat & Erntetechnik GmbH
Current assignee: Saat & Erntetechnik GmbH
Priority date: 1979-04-03
Filing date: 1979-04-03
Publication date: 1980-10-29
Also published as: GB2045056B

Abstract

In a process for the production of pelleted, granulated, incrusted seed material, using inorganic and/or organic substances, the untreated seed material is divided up into fractions according to parameters such as particle size, particle shape, specific weight and surface quality, the fractions are separately moistened and treated with differing coating compounds and the treated fractions mixed together and dried. The coating compounds contain coarse-particled long-fibre substances, or fine-particled, short-fibre substances, or substances having a greater or lesser water-absorption capacity, or substances having a greater or lesser adhesive power, or substances containing graduated amounts of hydrophobic or hydrophilic agents or active substances, or substances of different depths of colour.

Description

SPECIFICATION Process for the production of pelleted, granulated or incrusted seed material It is known to treat seed material with a coating compound without dividing the seed material into different fractions before treatment. With this method, a treated seed material is obtained wherein the various parameters such as particle size, particle shape, specific weight and surface quality are not taken into consideration. This method has the disadvantage that small seeds or those having a low specific weight have to be coated with a thicker layer of coating compound than larger seeds in order to obtain a specific pellet size or a particular particle size of the granules. However, a thicker coating is an obstacle to rapid germination.This is the case when the composition of the coating compound does not have the necessary water-absorption capacity and pore volume corresponding to the layer thickness of the coating compound.

According to the prior art, it is not possible to adapt the pure volume to the fractions of the seed material, when a mixture of large and small, or round and flat, seeds are pelleted.

Nor is it possible, according to the prior art, to adapt to the physiological germination properties of the seed fractions in the seed material with their different particle sizes, particles shapes, specific weight and surface qualities, whilst providing the right quality and quantity of coating compound.

In the known method, the composition of the coating compound is adapted only to the type of seeds, and not to the individual fractions within the type of seed. A process has now been found for pelleting, granulating and incrusting seed material of conventional composition using inorganic and or organic solid and liquid substances, which solves the problem of developing the known process so as to ensure optimum conditions for germination by taking into account the biological differences which may exist between the seeds.

The process according to the invention enables the different properties of the coating compound to be adapted to the properties of the seed fractions to an optimum degree. In this process, the term "fractions!' means partial amounts of seed batches which are obtained by dividing the seeds up according to their particle size, particle shape, specific weight and various surface qualities.

However, there are other appropriate parameters according to which the seed material can be divided into fractions.

According to the present invention, there is provided a process for the production of pelleted, granulated or incrusted seed material of normal composition, using inorganic and or organic solid and liquid substances, characterised in that the seeds in a batch which is to be processed are divided up into two or more fractions, each of which has a particular parameter, the fractions are separately moistened and treated with a particular coating compound and then the fractions thus treated are mixed together and dried.

The "particle size" of the seed material is determined by the diameter, in mm.

The "particle shape" of the seed material is determined in terms of any deviation from a spherical shape, by measuring a second diameter. These particle shapes may be flat, or pointed, or otherwise non-spherical.

By "specific weight" is meant the weight of the volume of seed in g/cm By "surface quality" is meant the various forms of the seed surface; this surface may be smooth, grooved, ribbed or hairy. Other differences in the surface of the seeds are known which are also included in the process according to the invention.

The "germinating conditions" for the seed material treated according to the invention are essentially dependent on the water supply, the density of the surrounding germination substrate, the air supply and the temperature during germination.

By "physiological germination properties" are meant, in particular, the reactions of the seed material to the germinating conditions, which are expressed as a greater or lesser speed of germination or capacity for germination.

By "long-fibre substances" are meant those measuring 0.5 to 1.0 mm, and by "short-fibre substances" are meant those with an average length of less than 0.5 mm, whilst in both cases the majority of the fibres, i.e.

more than 70 % by weight, are within these ranges.

By "porosity" is meant the ratio of air-conducting interstices between and within the solid particles of the coating compound.

By "low water-absorption capacity" of the coating compound is meant a water absorption capacity of about 300 g of water per kilogram of the coating compound when applied to the seed material. By substances with a "high adhesive power" is meant those substances which adhere to smooth surfaces owing to their physical properties. These substances include fine-particled bentonite, kaolin and vermiculite.

By substances with "lower adhesive power" is meant these same substances with a coarser structure of more than 0.1 mm.

German Patent specification 919328 discloses a coating for seeds consisting of finely divided sub-bentonite. This compound is intended to clump together round the seed as a result of the treatment and solidify by its own adhesive power. The treatment is intended to produce small spheres which are several times the size of the seed. The aim of this process is to produce coated seeds which are substantially uniform in size, shape and nature, so that the seeds are easy to handle.

German Patent specification 921 291 discloses a process for incrusting seed material. It sets out to provide a covering layer which contains a water-soluble binder and a porous, highly absorbent substance. An aqueous solution of water-soluble plastic material such as a methyl cellulose solution is used to spray the seeds. Feldsbar, for example, is used as the finely divided solid material. German Patent no. 960 241 relates to the coating of seeds. In this process, a binder is used which is capable of swelling in water and is also applied with inert fillers in one or more layers. This prior art is also described in similar terms in other publications. The proposed methods use the seed material without dividing it up into fractions having different properties. This teaching has hot been developed further.It therefore does not resemble the process according to this invention.

Only now when the new teaching makes it possible to divide the seeds up into fractions and treat them with different coating compounds, can the considerable advantages of the process according to the invention be achieved. There is no need to use any coating compounds not already known from the prior art.

It is, however, essential that these coating compounds be different for the individual fractions. as shown by the exemplary embodiments.

Suitable hygroscopic substances for the process according to the invention include MgCl, CACTI and glycerol.

Suitable hydrophobic substances for the process according to the invention include bentonite. vermiculite, methyl cellulose and phosphate starch.

The process according to the invention is preferably used for the seeds of sugar beet, beet for animal fodder, and vegetable and flower seeds.

The "graduated water-absorption capacity" can be adjusted by selecting varying quantities of substances which store or take up different amounts of water. Preferred substances include swellable bentonite and vermiculite. Preferred substances which do not swell include powdered stone.

The process according to the invention is described in the following embodiments by way of example.

However, the process is not restricted to these examples.

The process according to the invention is also illustrated by an example which compares the coated seed material according to the prior art with coated seed material according to the process of the invention, and thus confirms the technical progress achieved thereby.

The process according to the invention can be applied to any type of seed, by a suitable choice of parameters, and by dividing the seeds into fractions according to these parameters.

Example 1 100.00 kg of sugar beet seeds with a particle size in the round-hole screen of 3.0 to 4.5 mm are divided into 2 fractions with different particle sizes by screening: Fraction l: 44 keg of particle size 3.0 to 3.75 mm Fraction Il: 56 kg of particle size 3.75 to 4.25 mm Fraction I is moistened in a known coating apparatus and then dusted with a highly porous coating compound, and this procedure is repeated until a particular pellet size is obtained.

The highly porous coating compound consists of the following: 90 parts by volume of long-fibre sawdust 8 parts by volume of coarse-particled quartz dust 2 parts by volume of methyl cellulose.

Fraction II is treated in the same way.

The less porous coating compound consists of the following: 75 parts by volume of short-fibre peat dust 10 parts by volume of fine-particled bentonite 8 parts by volume of fine-particled kaolin 4 parts by volume of fine-particled vermiculite 3 parts by volume of methyl cellulose After these treatments, the pelleted seeds of fractions I and Il are mixed together in the original proportions Example 2: 100 kg of fodder beet seeds with seeds of different specific weights are divided into 2 fractions of higher and lower specific weight by gravity screening: Fraction l: 38 kg with a lower specific weight Fraction il: 62 kg with a higher specific weight Fraction I is moistened in a known coating apparatus and then dusted with a coating compound with lower water-absorption, and this operation is repeated until a particular pellet size is obtained.

The coating compound with a lower water-absorption capacity is made up as follows: 60 parts by volume of long-fibre sawdust 36 parts by volume of long-fibre peat dust 4 parts by volume of methyl cellulose Fraction II is treated in the same way.

The coating compound with a higher water-absorption capacity is made up as follows: 45 parts by volume of short-fibre sawdust 20 parts by volume of short-fibre peat dust 9 parts by volume of short-fibre bentonite 6 parts by volume of short-fibre vermiculite 10 parts by volume of short-fibre quartz dust 4 parts by volume of phosphate starch 6 parts by volume of methylcellulose After these treatments are complete, the pelleted seeds of fractions I and II are mixed together in the original proportions and dried.

Example 3 100 kg of sugar beet seeds with a particle size, through a round-hole screen, of 2.75 to 4.25 are divided into 2 fractions of different particle sizes by screening: Fraction 1 47 kg of particle size 2.75 to 3.5 mm Fraction II 53 kg of particle size 3.5 to 4.25 mm Fraction I is moistened in a known coating apparatus, then dusted with a coating compound containing a small added amount of hydrophilic and hygroscopic substances, and this operation is repeated until a specific pellet size is obtained.

The coating compound containing a small added amount of hydrophilic and hygroscopic substances is made up as follows: 75 parts by volume of long-fibre sawdust 15 parts by volume of fine-particled limestone dust 5 parts by volume of fine-particled bentonite 1 part by volume of calcium chloride 1 part by volume of glycerol 3 parts by volume of methyl cellulose.

Fraction II is treated in the same way.

The coating compound containing a larger added amount of hydrophilic and hygroscopic substances is made up as follows: 35 parts by volume of long-fibre sawdust 30 parts by volume of fine-particled limestone dust 10 parts by volume of bentonite, fine-particled 8 parts by volume of kaolin, fine-particled 7 parts by volume of vermiculite, fine-particled 4 parts by volume of glycerol 3 parts by volume of calcium chloride 5 parts by volume of methyl cellulose.

After these treatments, the pelleted seeds of fractions I and II are mixed together in the original proportions and dried.

Example 4: 100 kg of sugar beet seeds with a particle size, through a round-hole screen, of 2.75 to 4.25 mm are divided into 2 fractions of different particle sizes by screening.

Fraction I 52 kg of particle size 2.75 to 3.75 mm Fraction II 48 kg of particle size 3.75 to 4.25 mm Fraction I is moistened in a known coating apparatus and then dusted with a coating compound, and this operation is repeated until 150 kg of coating compound have been used up.

The coating compound may correspond to examples 1 to 3 in its composition, but contains a small amount (0.35 %) of the soil insecticide bendiocarb.

Fraction II is treated in the same way, until 50 kg of coating compound have been used up. The coating compound according to examples 1 to 3 contains, however, a larger amount (0.6%) of the soil insecticide bendiocarb.

After these treatments, the pelleted seeds of fractions I and Il are mixed together in the original proportions and dried.

Example 5: Comparison of the speed of germination and capacity for germination of pelleted sugar beet seeds according to example 3 and pelleted seeds according to the prior art.

The experiments were performed in a loess clay soil with a moisture level of about 40% of the water-absorption capacity and a moisture level of about 75% of the water-absorption capacity. Soil temperature 15-20"C; depth of sowing 2 cm.

Germination % Days Pelleted seeds according Pelleted seeds according to Example 3 to the prior art Water absorp. Water absorp. Water absorp. Water absorp.

cap. ca 40% cap. ca 75% cap. ca 40% cap. ca 75% 5 0 8 0 0 6 4 24 0 1 8 27 42 7 18 10 52 71 34 44 12 61 74 48 57 14 73 74 62 66 16 76 75 68 69 18 76 75 72 69 The results - particularly on the 6th and 10th days - show the higher speed of germination of the pelleted seeds according to the process of the invention. After only 12 days, virtually the final germination capacity is reached. The seeds according to the prior art, on the other hand, are slower to germinate and do not attain their final values until after 16 days. The final germination capacity is lower in the seeds according to the prior art and does not attain the values of the seeds according to the invention.

The process according to the invention has considerable biological advantages for the seeds which are treated in fractions and then mixed together and dried. These advantages consist in greater adaptability to different germinating conditions.

On the other hand, the seed material treated with a uniform coating compound according to the prior art is suitable only for specific, restricted germinating conditions.

If these conditions for which the seeds were treated with a coating compound of a particular composition are not present, the speed of germination and capacity for germination of the seeds are reduced.

These disadvantages are avoided with the seeds produced according to the process of the invention. This process has the considerable advantage that the seeds, divided up into fractions and treated with coating compounds of different compositions and properties, can be mixed together and dried and then are suitable for the various biological conditions which may obtain.

However, the process of the invention also has technological advantages. Dividing the seeds into fractions according to various parameters is an additional step of the operation. Nevertheless, the operation is faster when the individual fractions are treated, owing to the increased thrnughput. This is due to the greater homogeneity within each fraction.

The process of the invention is also more economical, as the use of coating compounds of different compositions to suit the individual fractions means that there is less waste.

Claims

1. Process for the production of pelleted, granulated or incrusted seed material of normal composition, using inorganic andior organic solid and liquid substances, characterised in that the seeds in a batch which is to be processed are divided up into two or more fractions, each of which has a particular parameter, the fractions are separately moistened and treated with a particular coating compound and then the fractions thus treated are mixed together and dried.

2. Process according to claim 1, characterised in that the fractions thus treated are mixed together in a different ratio and dried.

3. Process according to one of claims 1 and 2, characterised in that the fractions are divided up according to their particle size, particle shape, specific weight or surface quality.

4. Process according to one of claims 1 to 3, characterised in that, if the particle size or particle shape or specific weight is used as the parameter, the fraction with the small particle size or flat particle shape or low specific weight is treated with a coating compound containing coarse-particled and/or long-fibre substances, in order to attain a higher porosity, and the fractions with larger particle sizes or a more rounded particle shape or a higher specific weight are treated with a coating compound consisting of graded fine-particled and/or short-fibre substances, in order to attain a lower porosity.

5. Process according to one of claims 1 to 4, characterised in that the fraction with a small particle size or flat particle shape or low specific weight is treated with a coating compound having a low water-absorption capacity and the fractions with larger particle sizes or a more rounded particle shape or higher specific weight are treated with a coating compound having a graduated and increased water-absorption capacity.

6. Process according to one of claims 1 to 5, characterised in that, if the surface quality is used as the parameter, the fraction with a smooth surface is treated with a coating compound containing fine-particled substances of high adhesive power and the fractions with a rougher or grooved surface are treated with a coating compound containing graded coarse-particled substances of lower adhesive power.

7. Process according to one of claims 1 to 6, characterised in that the fraction with a small particle size or flat particle shape or low specific weight is treated with a coating compound containing a larger added amount of hydrophobic substances and the fractions with larger particle sizes or more rounded particle shapes or higher specific weights are treated with a coating compound containing a smaller, graded amount of hydrophobic substances.

8. Process according to one of claims 1 to 7, characterised in that the fraction with a small particle size or flat particle shape or low specific weight is treated with a coating compound containing a smaller added amount of hydrophilic and/or hygroscopic substances and the fractions with larger particle sizes or more rounded particle shapes or higher specific weights are treated with a coating compound containing a larger added amount of hydrophilic and/or hygroscopic substances.

9. Process according to one of claims 1 to 8, characterised in that the fraction with a small particle size or flat particle shape is treated with a coating compound containing less active substance and/or plant protecting agents and the fractions with larger particle sizes or more rounded particle shapes are treated with coating compounds containing larger, graded amounts of active substance and/or plant protecting agents.

10. Process according to one of claims 1 to 9, characterised in that the fraction with a small particle size or flat particle shape and the fractions with larger particle sizes or more rounded particle shapes are treated with coating compounds of different colours and/or containing different dyestuffs and/or with substances of different depths of colour.

11. Process for the treatment of seed material substantially according to any one of the examples herein.