HU201582B - Method for producing barrier layer improving the water and nutrient recycling of soils - Google Patents

Abstract

Prodn. of a barrier layer which improves the water and nutrient retention of soils, partic. sandy soils, is characterised in that: a layer of clay mineral/polymer gel capable of reversibly binding and releasing water is introduced into the soil, pref. 20-60cm below the surface, in such a way that the clay is reacted before or after or during activation in presence of water, with 0.5-30 wt. % (on wt. of clay) of water-soluble polymer(s) capable of reacting with the clay; the water content of the resulting gel is adjusted before or after or during reaction to a value at which the resistance of medium of the gel is at least 3 times higher than that of a polymer-free suspension contg. the same amt. of clay, if non-activated clay was used; the clay mineral is activated with an alkaline activating agent after reacting with the polymer; if desired, further amts. of water-soluble polymer, water-insoluble swelling xerogel(s) capable of at least 100% water uptake and forming swollen particles less than 1mm in dia., and/or agricultural chemical(s), pref. plant nutrient, soil fungicide and/or plant growth promotant, is added to the gel before or after or during reaction with the polymer; and/or, if desired, the gel and the non-reacted polymer molecules are crosslinked with an aldehyde; and, finally, the obtd. gel layer is covered with a soil layer.

Description

The present invention relates to a process for producing a barrier layer which improves the water and nutrient retention of soils, in particular sandy soils.

It is known that sandy soils, especially arid and semiarid areas, have low aqueous nutrient retention. The water introduced into the sandy soils in the form of natural rainfall, irrigation or drip irrigation, or subsoil irrigation, is relatively quickly drained into deep layers of the plant that the root system can no longer reach, rendering the water unusable for the plants. The water flowing into the deeper layers of the soil, for example, absorbs some of the nutrients applied to the soil, which, in addition to increasing the chemical and water requirements of agricultural treatments, also leads to environmental pollution.

The water and nutrient retention capacity of the sandy soils has been enhanced by the placement of suitable barrier layers. It is known, for example, to place a thin waterproof layer of plastic film or bitumen emulsion 20-60 cm below the soil surface in sandy soils, which prevents leakage of water to the soil [Horánszky, Szabó, Túri: Plastics in Agriculture 243-249 . (Technical Publisher, Budapest, 1979)].

A major disadvantage of this solution is that large amounts of foreign materials are introduced into the soil, which decompose very slowly (sometimes over decades) and contaminate the soil for a long time. The roots of the plants are unable to penetrate the plastic and bitumen emulsion layers, which causes an abnormal growth of the root system, which also inhibits the development of the above-ground parts after a shorter or longer period. The waterproofing membranes used to date greatly reduce the flow of airborne gases and gases in the soil (i.e., impair the ventilation of the soil), which slows down the activity of the aerobic microorganisms in the soil by inhibiting their activity.

There is therefore a need for a barrier layer that improves soil water and nutrient retention to an adequate degree, but does not pollute the environment, hinder future agricultural work in the area, or adversely affect the natural development of the crop or the functioning of soil microorganisms.

In our experiments, we have discovered that gels with a specific structure, reversible uptake and release formed by the reaction of clay minerals and polymers are perfectly capable of meeting these goals.

Nos. 186,325 and 189,280. It is known from Hungarian Patent Application Laid-Open Patent Application Nos. 4721/84 and 3386/84 that certain special swellable clay minerals react with water-soluble polymers to form stable-form gels which are capable of reversibly binding and releasing water. It is also known that these gels, when mixed with soil, are capable of controlling the water content of the soil by allowing the discrete gel fragments introduced into the soil to absorb moisture from the soil and transfer their water content to the roots of the plants. However, it was not known that the layers of such gels were able to penetrate the roots of the plants so that the gel layer adheres to the roots at the point of penetration so that no gap is formed in the waterproofing layer. It was also not known that layers of such gels do not impede the normal ventilation of the soil, and that air and various gases and vapors can pass through them at lower speeds. Due to their listed beneficial properties, the gel layers do not inhibit the normal development of the plants or the life of aerobic soil microorganisms. These experiences are extremely surprising, as in the patents cited above we could expect that gels formed by the reaction of polymers and clay minerals behave in the same way as plastic films used to date, as a waterproofing layer! their application will therefore necessarily lead to abnormal growth of the root system and inhibition of the vital functions of soil microorganisms.

The present invention therefore relates to a process for producing a barrier layer which improves the water and nutrient retention of soils, in particular sandy soils. According to the invention, a reversible water uptake / drainage clay mineral polymer layer is applied to the soils, preferably to a depth of 20-60 cm below the soil surface, with the clay mineral in the activated or inactivated state or in the presence of water 5 to 30% by weight of water-soluble one or more polymers capable of reacting with the clay, adjusting the water content of the resulting gel before, after, or during the reaction to a resistance of the gel to the fluid resistance of the same amount of clay minerals is increased at least three-fold relative to the polymer, and when starting from an inactivated clay mineral, the clay mineral is activated by the addition of an alkaline activator after reaction with the polymer, where one or more xerogels and / or agrochemicals, preferably plant nutrients, soil fungi, to form an additional water-soluble polymer, at least ΙΟΟΧ water-absorbable, water-insoluble, but water-swellable, granules of a size less than 1 mm when swollen fungicidal agents and / or growth promoters are added and desired

HU 201582 In this case, the gels and unreacted polymer molecules are cross-linked with aldehyde, and the gel layer formed in the soil as described above is covered with a layer of soil.

The preparation of clay mineral / poliraer gels is known from the previously cited Hungarian patents and patent applications. The term "clay mineral" as used in the references cited herein, refers only to triple layer phyllosilicates and chain silicates, and to rocks, mining products and artificial mixtures containing at least 10% by weight (preferably 20-80% by weight) thereof. Examples of clay minerals that can be used include: Na-bentonite, activated (i.e. pretreated with Na-salt or other activating agent) Ca-bentonite, illite, attapulgite, allevardite, hectorite, nontronite. Natural clay minerals are preferably used in the activated state, since they are much more readily reactive with the polymer and, at their reactive sites, are attached to the polymer chain, providing stability of the gel structure. Activation refers to known treatments (e.g., kneading with sodium carbonate, etc.) to increase the swelling capacity of the clay mineral; during activation, the clay minerals are predominantly disintegrated on their elemental bundles or chains and these elemental bundles or chains react with the polymers.

If the clay mineral is reacted with the polymer in an inactive state, the reaction product is subsequently activated by treatment with an alkaline activator. An overactivated (i.e., excess activator) clay mineral may also be used as the alkaline activator. In this case, too, the clay mineral disintegrates into sheets or chains during activation and the reactive sites liberated subsequently react with the polymer to form a stable structure gel.

Any water-soluble polymer which may react with the clay may be used to prepare the clay mineral polymer gels, in accordance with the cited publications; examples of such reactive groups include water-soluble polymers containing - COOH, -COO'M * (M * being a monovalent cation), -CONH2, OH and / or -C-O-C-. Examples of such polymers include: polyacrylamide, polymethacrylamide, polyacrylic acid, polymethacrylic acid, hydrolyzed polyacrylamide, acrylamide-acrylic acid copolymers, hydrolyzed acrylamide-acrylic ester copolymers, polyvinyl alcohol-acrylic acid copolymers, polyvinyl esters, polyethylene oxides, water soluble polysaccharides, etc., and mixtures of the listed homo- and copolymers. The polymers may also be graft copolymers; for example, copolymers containing acrylic acid methacrylic acid, acrylamide and / or methacrylamide side chains grafted on a cellulose or other polysaccharide side chain, and a -CONH2 and / or -COO'M * group grafted with acrylonitrile and then hydrolyzed. containing copolymers.

The molecular weight of the polymers that can be used will generally be in the range of 50,000 to 20,000,000, preferably in the range of 500,000 to 10,000,000.

It is essential to adjust the water content of the gel before, during, or after the reaction between the clay mineral and the polymer so that the gel has a fluid resistance of at least three times that of an aqueous suspension containing the same amount of clay minerals.

It is also possible to form the zero layer in the soil by spraying the dry powder of the gel prepared as described above with a suitable amount of water which causes the gel powder to swell and form a coherent layer. However, it is significantly simpler, more economical and expedient to apply the gels as hydrogels (i.e., water-containing gels) at the rate at which they are formed. In this case, one gelling reagent or reagent mixture is introduced into one container of a two-reservoir power plant, another reagent or reagent mixture is formed into another container, and the two reagents are vigorously mixed with each other at the outlet of the containers and The resulting gelling mixture is immediately introduced into the soil, where the reaction takes place and a gel is formed within a short time (1-100 sec). The resulting gel usually reaches its final mechanical properties within a maximum of 1 day. For example, the following fluids may be added to the container pairs:

Tank 1 Tank 2 activated clay mineral suspension aqueous solution of polymer unactivated clay polymeric aqueous solution prescription suspension ta + activator (eg Na2CO3) reacted with polymer- activator (e.g. tott is not activated overactivated bentonite clay mineral water aqueous suspension suspension y or aqueous Na2COa solution)

As is known from Hungarian Patent Applications Nos. 4721/84 and 3386/84, if desired, it is highly swellable in water into the clay mineral polymer gel structure, but vi green inert xerogel-35.

HU 201582 A

embedding granules and / or incorporating agrochemicals into the gel structure. These materials may be added to any of the reagent mixtures, but may subsequently be applied to the finished gel formed. If desired, the gel structure may be subsequently cross-linked with aldehyde treatment together with the additives.

In a very convenient embodiment, the tank containing the two liquid components (mounted on a power plant and connected to the power plant by a poultry flap. The liquid component leaving the two tanks is pumped through a laryngeal tube to a The about 20-60 cm thick soil layer raised by the wings directly covers the applied gel layer, which is already firm when the layer is applied, so that its structure is not damaged by the shaking soil layer.

If the surrounding soil is dry, the applied hydrogel will transfer most (about 50-75%) of the water in it to the circular? soil, while decreasing in thickness. When the soil layer above the hydrogel is naturally or artificially saturated with water, the hydrogel is also swollen, and this drying-shrinkage-swelling process is reversible many times. Salts of alkali metals, water-soluble non-ionic organic molecules do not affect the swelling capacity of the hydrogel. Polyvalent metal ions dissolved in water, acid-dissociating inorganic or organic compounds, reduce the swelling capacity of the hydrogel. However, the swelling capacity of the hydrogel can be regenerated by using alkaline activating agents such as sodium carbonate or sodium phosphate; this treatment should be carried out at the end of the growing season, after harvesting, and the activator, together with the irrigation water, should be applied to the hydrogel.

The invention is further illustrated by the following non-limiting examples.

fluid was weighed by power plant pumps at a 4: 1 by volume and mixed vigorously. The power plant was connected to a winged wagon, to which a mixture of the two fluids was printed through a plastic laryngeal tube at a rate of 0.1 m ³ / min. The already gelling mixture proceeded vertically downward in the stalk of the wing, then at right angles and disassembled for approx. It passed through an opening 4 mm thick and 600 mm wide. The gel spreading tool was located inside the upper plate cover at the back of the poultry blade. The propulsion machine was driven at 3 km / h while steadily moving for approx. It applied a 3-4 mm thick gelatin to the soil. The power reservoir tank is approx. After 25 minutes of operation, it was refilled and the gel applied.

At the same time, with the help of fowl, al20 soil irrigation tube was embedded in the soil for approx. 10 cm above the gel. The sub-irrigation tube was placed 45 cm below the surface and the gel layer 55 cm below the surface, between the rows of vines 3 m apart. Two rows of the same irrigation tube were introduced at the same distance with a 60 cm wide PVC film.

By operating underground irrigation for one year, the yield of the young single crop rotating soles was 15% higher in the gel coated rows according to the invention than in the known PVC zero-coated rows.

Example 2

The procedure was the same as in Example 1, except that a row of apple seedlings planted 1 year earlier was applied at a depth of 45 cm below the soil surface and no under-watering tube was placed. Due to the better utilization of the natural precipitate, the rows with the gel barrier layer will be ca. They achieved an average height of 10 cm in the unstressed rows, which was approx. This corresponds to a development difference of 30%.

Example 1

Two tanks, 110 KW power plant, one tank contains 2 m ^{3 of} 15 wt% dry solids F2 activated bentonite suspension (manufactured by National Ore and Minerals Company, Mad), the other tank 500 liters, 2 wt% dry solids polyacrylamide solution. The two main

Claims (1)

Patent Claim Point A process for producing a barrier layer to improve water and nutrient retention in soils, comprising applying to the soils a reversible uptake / release clay mineral layer, preferably 20-60 cm below the soil surface 5, by activating or activating clay minerals. water is soluble in one or more polymers capable of reacting with the clay compound in the presence of 10 water, based on the weight of the clay mineral, the water content of the resulting gel is adjusted to a value before, during or after the reaction. fluid resistance increases at least three times the fluid resistance of the same amount of clay mineral but polymer-free sulfur suspension, and when starting from 20 inactivated clay minerals, the reaction of the clay mineral with a polymeric tin, and optionally adding one or more additional water-soluble polymer to the gel prior to, during, and / or after the reaction, one or more water-soluble but water-swellable particles having a swollen state of less than 1 mm adding xerogels and / or agrochemicals, and optionally crosslinking the gels and unreacted polymer molecules with aldehyde; and then covering the gel layer formed in the soil with the above layer. 35 Published by the National Office for Inventions, Budapest Responsible: dr. Gabriella Swaboda Head of Department R 4969 - KJK