DE1287357B - Process to increase the water retention capacity of agriculturally used soils - Google Patents

Description

It is known that by treating methacrolein polymers or - Copolymers with stronger bases to produce polymeric products that are dissolve in water and can be used as soil improvers (German patent specification 1024 714). The soils treated with such soluble polyelectrolytes have improved mechanical properties. To improve the water retention capacity however, they are not suitable.

It is also a process for the production of plant physiological effective gels known (German Patent 940 404). These gels are created by Precipitation of alkali silicate solutions with organic acids and are used after dehydration and drying mixed with the soil. However, such water glass gels are not reversible swellable and therefore also unsuitable for increasing the water retention capacity.

In contrast, the present invention relates to a method for Increasing the water retention capacity of agricultural soils, in particular of sandy soils, by treating with gel-forming synthetic polymers, which is characterized in that the soils with from acrolein polymers and alkali hydroxides manufactured, finely ground gels, either as such or in the form of their aqueous slurries are used.

Various methods exist for the preparation of the aqueous gel slurries Options. The polymerizates, which are finely divided in water, are thus formed during the reaction of acrolein with alkali hydroxide solutions initially a viscous solution, which becomes a solid gel block solidified. This gel block can after grinding in colloid, ball or Paint mills can be slurried with water.

In a preferred form, however, the gel slurries can also can be obtained by complete solidification during gel production the gel solution avoided by intensive stirring and the formation of a gel block is prevented. Instead of the block, a slurry is created during gel production of gel particles in an aqueous medium. This can then be added to the desired with water Solids content can be diluted. Depending on the stirring speed arise here larger or smaller particles. If the stirring speed is high, they are resulting gel particles are smaller down to the order of size of colloidal particles.

The aqueous slurries generally contain only proportionally small amounts of gel particles. In most cases, a solid content is sufficient from 1 to 5 percent by weight for sealing.

The aqueous gel slurries can preferably also be used an emulsifier.

The practical implementation of the soil improvement is carried out by that the gels, either as such or in the form of an aqueous slurry, hit the floors are mixed in. If an aqueous slurry is used, admixing takes place generally by casting. When the gel slurries are poured, a dense one is created Layer of gel particles that hold the water in the atmosphere while swelling and prevent further leakage. This way it becomes a complete dehydration the layer below. Such a closed layer of gel particles only needs to be 1 mm thick to completely seal against water.

Likewise, preferably only very specific soil layers with the Gels are treated. By incorporating them into certain layers in this way the floors can, for. B. the plant growth (short and long roots) for different Plants are regulated differently or even completely to die off (weed killing) to be brought.

In general, gels are used that are prepared before slurrying in water already have a high water content of up to 90 percent by weight, for example. In some cases it may be beneficial to use partially dried gels with one Use solids content of 50 to 70 percent by weight. These gels swell Water access to their full size again; you can also dry with others Additives such as fertilizers can be used mixed. When using partially dried Gels mixed with fertilizers, it is z. B. possible to add fertilizers to sandy soils and at the same time have a favorable influence on their water balance.

The aqueous gel slurries can preferably with acids, in particular Nitric acid. If the neutralization is carried out with nitric acid, so the nitrate formed adheres firmly to the gel particles and the gels act at the same time as fertilizer.

A particular advantage is the stability and thus the portability the aqueous gels; therefore they do not have to be manufactured at the point of use. In addition, as a one-component system, they are particularly easy to handle. Example Dry, fine-grain construction sand is moistened with so much water that that a maximum degree of moisture penetration is achieved without the mixture flowing entry. This condition is at a ratio of 86 weight percent sand and 14 Achieved weight percent water.

At the same time, similar mixtures are produced which also contain small amounts of polyacrolein gel and, through neutralization, small amounts of sodium nitrate. The mixtures, the composition of which is given in the table below, are poured into plant boxes measuring 30 X 30 cm, 4 cm high. The plant boxes have a bottom made of fine-meshed wire mesh so that excess water can run off. It is dried at 20 to 25 ° C and the remaining water content in the sand mixtures from the top, 1 cm thick layer is determined by drying for 1 hour at 120 ° C. While the water-sand mixture is completely dry after 4 days, the other mixtures still contain moisture due to the water-binding gel additive according to the following overview: Gel additive NaNO, 3 water content of the samples in percent by weight Weight- Weight- on after after after percent percent start ' I day 2 days I 4 days - - 14 5 3 0 0.5 1 14 9 8 5.5 0.25 0.5 14 9 8 5.5 0.1 0.2 14 9 7 5 0.05 0.1 14 8 6 4.5 In addition, after 4 days the sample without gel addition is without any solid consistency and dusts, while the gel-containing samples have firm cohesion and do not dust.

Newly added water is removed from the gel-containing sand samples in about 30% larger amounts bound than from the sand alone.

Such polyacroline gels containing sand samples are suitable for Cultivation of all kinds of plants.

Claims (5)

Claims: 1. Method for increasing the water retention capacity Agricultural soils, in particular sandy soils, by treating with gel-forming synthetic polymers, characterized in that the floors with finely ground ones made from acrolein polymers and alkali hydroxides Gels which are used either as such or in the form of their aqueous slurries, be treated. 2. The method according to claim 1, characterized in that partially dried gels with a solids content of 50 to 70 percent by weight are used will. 3. The method according to claim 1 and 2, characterized in that the aqueous Gel slurries are neutralized with acids, especially nitric acid. 4. The method according to claim 1 to 3, characterized in that certain soil layers treated with the gels. 5. The method according to claim 1 to 4, characterized in that that the aqueous gel slurries are prepared using an emulsifier will.