DK169569B1 - Use of a mixture which comprises a nitrogen-containing fertiliser and a strong mineral acid as a slurry- improving agent for decreasing ammonia evaporation therefrom, a slurry product with decreased ammonia evaporation, and a process for producing such a product - Google Patents

Description

in DK 169569 B1

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the use of a mixture comprising a nitrogenous fertilizer and a strong mineral acid as a slurry enhancer for reducing ammonia evaporation thereof, a slurry product with reduced ammonia evaporation, and a process for producing such a product.

Ammonia evaporation after dispersal on slurry field surfaces is responsible for a large loss of nitrogen from the slurry. This reduces the value of manure as 10 fertilizers and the evaporated ammonia can, dissolved in rainwater, cause pollution with nitrogen in undesirable places, for example by lakes and streams. The poor utilization of nitrogen in the slurry results in a higher fertilizer consumption in the form of slurry. Under Danish law, 15 slurries cannot be released all year, as there is a high risk of leaching at certain times. This means that agriculture must be able to store manure for months, and almost all farms with animal production have a manure tank today. The size can vary greatly, but is on average about 2000 m3.

When the manure is to be dispensed, usually during the months of March / June and in the autumn months of September / November, the farmer often contacts his machine station to arrange the application. This process 25 is expensive as the machines used are very expensive. When the manure is applied, the farmer will typically fertilize at a later stage in the spring with another fertilizer to get optimum yield.

The problem is discussed by R.J. Stevens et. al., J.

30 Agricultural Science, 113 (1989) 389-395, which also mentions older references to the subject. It is mentioned that 24-80% of ammonium nitrogen can be lost within the first week after application of slurry on field surfaces. The problem becomes less if the slurry is degraded immediately after the application or in connection with the application is injected into the field surface. However, as early as 1938, DK 169569 B1 2 found that this could be avoided if the pH of the slurry was lowered in order to reduce the ammonia evaporation from it. Phosphoric acid and monocalcium phosphate were found to be effective agents for such a lowering of pH in the slurry. However, these additives are not cheap and their use can also cause phosphate overgrazing. For this reason, other mineral acids such as sulfuric acid and nitric acid have been proposed for the purpose, as these 10 chemicals are cheaper than the ones used above.

Thus, from DE Publication No. 3,826,247, a process for working up especially manure by adding so much strong mineral acid, especially sulfuric acid or phosphoric acid, is known that the pH value herein is preferably 5.5-6.5. The product thus obtained can be spread as fertilizer after evaporation and drying.

The following table illustrates the relationship between the percentage loss of ammonia nitrogen (cumulatively after 3.25 days) and the value of the pH of the slurry from 20 porcine manure (3 test samples, S2 and S3) and cattle manure (3 test samples, K1 # K2 and K3).

_ TABLE_ _EH_ 25 Slurry_7.0 6.0 5.5 5.0 4.5 4.0

Sx 26.5 3.8 1.7 1.5 0.9 0.8 52 23.4 3.5 2.9 2.2 0.4 0.4 53 19.7 5.6 3.7 1, 8 1.6 0.8

Mean 23.2 4.3 2.8 1.9 0.9 0.7 30 ,7 28.7 8.1 1.5 1.7 1.0 0.3 K2 22.9 7.0 1.9 0 , 6 0.6 0.5 K3 34.4 7.1 0.5 0.6 0.4 0.3

Mean_28.6 7.4 1.3 1.0 0.6 0.4

It is seen that the nitrogen loss is large at pH 7.0 but decreases sharply when the pH is lowered below this value.

35 3 DK 169569 B1

Husted it. al., J. Sci. Food Agric 57 (1991) 335-349, has investigated the effect on pH of adding acids or various salts to manure and found that acids had the best effect in this regard, although pH 5 in manure could be reduced by salt addition, but The pH increased again after aeration of the slurry.

It will be seen that the above problem can in itself be solved if you add so much acid (preferably 10 sulfuric acid, but other strong mineral acids can also be used) to the slurry that its pH is reduced to a value in the range 4-5. However, it is not advisable for the farmer to work locally with strong acids, as, for example, it is not without risk of having to work with 15 sulfuric acid, which is why certain safety requirements must at least be complied with in this regard.

There is thus a need for a slurry improver which can lower the pH of slurry to a value in the range 4-5 and which is also cheaper and less dangerous to work with than sulfuric acid.

U.S. Patent No. 4,315,763 discloses a liquid fertilizer product having a pH value between 1.5-4 and comprising the reaction product between urea and phosphoric acid and optionally also the reaction product between urea and sulfuric acid and optionally potassium chloride and trace elements. It is explicitly mentioned that in the manufacture of this product, water should not be added beyond what is already present in the acids used, and it is neither mentioned nor implied that the product can be used to reduce the pH in slurry in order to reduce ammonia evaporation from the slurry.

Corresponding reaction products or mixtures are also known in principle from US Pat.

Nos. 4,310,343, 4,397,675, and 4,962,283, but neither here nor are 35 mentioned the applicability of the mixtures for reducing slurry ammonia vaporization.

DK 169569 B1 4

It has now surprisingly been found that a mixture of the aforementioned kind which is in liquid form and having a pH below 2 can be successfully used to reduce the pH of slurry to the above-mentioned desired values, 5 and at the same time is much less dangerous to work with than sulfuric acid.

If the farmer puts such a remedy on slurry just before or during its application, the evaporation of slurry will be reduced, in cattle slurry by 10 up to 95% and in pig slurry up to 82%, which means far better utilization of slurry, far less odor nuisance. for the environment and less nitrogen pollution of streams and lakes in the surrounding area, and that by this one application of the manure the farmer will be able to fertilize his field without the need for fertilizer. This also means a saved drive, typically at DKK 100 per day. ha.

Accordingly, the invention relates to the use of a liquid form mixture having a pH value below 2, the mixture being prepared from a nitrogenous fertilizer selected from N, NP and NPK fertilizers or mixtures thereof, a strong mineral acid and water, as well as, if desired, additives, as slurry enhancers to reduce ammonia evaporation from slurry.

The mixture used in the application of the invention will hereinafter be referred to as the present blend or slurry enhancer.

The nitrogenous fertilizer is preferably an N fertilizer which essentially comprises urea and the strong mineral acid is preferably sulfuric acid.

The slurry improvement agent is preferably prepared (per 1000 kg of mixture) from 50 to 350 kg of urea and 200 to 350 kg of concentrated sulfuric acid and the remainder of water, the amount of water being within the range of 300-700 kg. The limits stated for the weight amount of concentrated sulfuric acid correspond to a 96% by weight sulfuric acid and the limits must be changed accordingly if the concentrated sulfuric acid has a different strength.

The composition of the present invention may further comprise up to 2% by weight, based on the total weight of added water, mineral acid and nitrogenous fertilizers, of additives comprising. trace metals selected from zinc, manganese, aluminum, magnesium, copper and iron, and / or 10 dyes.

The trace metals can be added in the form of cheap inorganic compounds which are water soluble or at least acid soluble.

The use according to the invention is, in a preferred embodiment, one in which: a) the contents of the slurry tank are thoroughly stirred and the mixture as defined above is added, after which the improved slurry is thus dispensed on the same day or latest the next day, or b) the mixture as defined above. (c) the mixture as defined above during application of slurry is added to the slurry in the slurry distributor system, using in each case 1-5 kg, and preferably 3-4 kg of the mixture as defined above. 100 kg slurry.

The present slurry enhancer is a clear liquid having a pH in the range of just over 0 to below 2, preferably up to 1.5. For safety reasons, the product can be dyed and those skilled in the art will know dyes which are stable in sulfuric acid solution. Studies have shown that the manure enhancer in question is harmless to humans, as it does not corrosive to it on short contact with the skin. If the product comes into contact with mucous membranes, such as in contact with the eye, a sensation of burning will occur and you should immediately rinse with cold water. However, the agent is corrosive to metals and must therefore be stored in special plastic tanks or coated metal tanks.

If, during storage or use of the composition in question, a leakage occurs, the product can simply be neutralized with lime, or the soil contaminated with the product can be excavated and spread over a field, thereby simultaneously fertilizing the field.

The manure enhancer of the invention may be prepared by a process whereby in an acid-resistant container provided with a powerful stirrer in order and with stirring, water, any additives, the nitrogenous fertilizer and the strong mineral acid to form the manure enhancer, are introduced. in liquid form, after which the product is drained.

This method is preferably carried out by providing a strong stirrer in an acid-resistant container per minute. 1000 kg of mixture, calculated without any additives, with stirring introduces: 300-700 kg of water, any additives in quantities as indicated above, and 50-350 kg of urea, then with continued stirring to the strongly cooled mixture 200-350 kg concentrated sulfuric acid, calculated as 96% by weight of sulfuric acid, to give the liquid slurry enhancer in question and the product is then drained off.

The manure product with reduced ammonia evaporation is peculiar in that it comprises conventional manure, especially pig manure or cattle manure, to which 35 100 kg slurry is set at 1-5 kg and preferably 3-4 kg of slurry enhancer as defined above.

7 DK 169569 B1

The manure product according to the invention can be prepared by a method which is characterized in that by conventional manure, such as pig manure or cattle manure per day. 100 kg slurry puts 1-5 kg, and preferably 5 3-4 kg, of the liquid slurry enhancer as defined above.

The invention will be described in greater detail below with reference to Preparation Examples (1-3) and Application Examples (A-D).

In a preferred embodiment of the manure improvement agent, the nitrogenous fertilizer used in the preparation of the agent is an N-fertilizer which essentially comprises urea. If the application of phosphate to the fields in connection with the application of manure is not a problem, an NP fertilizer can also be used. Furthermore, the enhancer has been attempted using NPK fertilizer, but may in some cases contain precipitated haze and should be stirred or shaken before use.

The strong mineral acids which are included in the slurry improvement agent can be, for example, sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid or mixtures thereof, preferably sulfuric acid, hydrochloric acid or nitric acid and especially sulfuric acid.

In the preparation of the agent, the sulfuric acid is preferably used as concentrated sulfuric acid, such as a 96% by weight sulfuric acid.

Since the acid 30 used in the preparation of the agent and the slurry enhancer itself in question acts corrosively to metals, acid-resistant materials must be used during the preparation of the agent for the equipment which comes into contact with the acid or with the agent.

For a production of approx. Typically, 10 tonnes of slurry enhancement agent, a container with a volume of approx. 10 m3, for example made of 8 DK 169569 B1 PVC or of epoxy coated iron. The container must be provided with a powerful stirrer, such as a auger, and the stirring can be further enhanced by a conduit for recycling the contents of the container from bottom 5 to the top of the container.

Advantageously, a tapping device for the manufactured agent may be placed on the lower portion of this recirculation line.

In a production as mentioned above, 10 first places the required amount of water in the container and adds the necessary additives with stirring to dissolve or slurry them. Then the amount of urea used is added with vigorous stirring with the auger. It is known that dissolution of urine substance in water takes place under heavy heat absorption, and it is then also observed that the temperature of the contents of the container drops to 0 ° C. When the added amount of urea has dissolved, after approx. For 1 minute, gently stir the required amount of concentrated sulfuric acid to the contents of the container and continue stirring for approx. 1 minute, after which the agent, which has now reached 0 a temperature in the region of 50 ° C due to the solution heat of the sulfuric acid, can be drained onto a suitable tank or container. Such tanks or containers 25 may be made of stainless steel or plastic.

As mentioned, the enhancer is a water-clear liquid with a pH below 2 and has a density of about 1.2 g / cm 3. The color of the agent depends on the added dyes.

When the slurry enhancer in question is to be mixed with slurry to obtain a slurry with low ammonia vaporization and this slurry must then be applied, one should proceed as mentioned above in connection with the preferred use. The manure product in question should be provided with a tow hose trolley.

EXAMPLE 1 In a PVC container with stirrer auger and circulation line, supply and drainage devices 5, as described above, a slurry improvement agent was prepared from 553 kg water, 217 kg urea and 230 kg 96% by weight sulfuric acid. 1000 kg of product. The product was water clear and had a pH of 0.95. The density was 1.20 g / cm 3.

EXAMPLE · 2

Proceed as in Example 1, using 662 kg of water for the preparation of 1000 kg of agent, 15 108 kg of urea and 230 kg of 96% sulfuric acid. The product was water clear with a pH of 0.95. The density was 1.16 g / cm 3.

EXAMPLE · 3 20

Proceeding as in Example 1, an agent was prepared from 444 kg of water, 326 kg of urea and 230 kg of 96% sulfuric acid per liter. 1000 kg of product. The product was water clear with a pH of 1.30, the density was 1.23 25 g / cm 3.

EXAMPLE A

To a pig slurry having a pH 8.0, 3.8% by weight of the agent of Example 1. 3.8 was added. The slurry product thus produced had a pH of 4.73 after stirring and the value was stable at some days standing.

35 DK 169569 B1 10

EXAMPLE B

To a cattle slurry with pH 7.5, 4% by weight of the agent of Example 1 was added. After stirring, the slurry product had a pH of 5.1 and the value was stable for a few days.

EXAMPLE C

To a pig manure with pH 8.0, the variant was added to the weight amounts of the agent of Example 2. The results are shown in Table 2 below.

Table 2_ 15 Amount of agent added from Example 2

% wt _pH

1.8 6.89 20 2.7 6.50 3 5.60 3.7 4.80 4 _ 4.75 25 It is seen that in this slurry the pH can be reduced to a value which greatly reduces ammonia evaporation from the slurry using 3-4% by weight of a subject enhancer, namely the agent of Example 2.

EXAMPLE D

To a pig manure with pH 7.7 was added 1.8% by weight of the enhancer of Example 3. After stirring, a pH of 5.81 was measured. At this pH the ammonia evaporation is already somewhat reduced. However, a comparison with the results of the above Example C shows that in this case some more of the agent of Example 3 should be used, probably about 3% by weight.

Claims (8)

Use of a liquid-form mixture having a pH value below 2, the mixture being prepared from a nitrogenous fertilizer selected from N, NP and NPK fertilizers or mixtures thereof, a strong mineral acid and water, and if desired, additives such as slurry enhancer to reduce ammonia evaporation from spent slurry. Use according to claim 1, characterized in that the nitrogenous fertilizer is an N-fertilizer which essentially comprises urea. Use according to claims 1-2, characterized in that the strong mineral acid is sulfuric acid. Use according to claims 1-3, characterized in that the mixture per 1000 kg is prepared from 300-700 kg of water, 50-350 kg of urea and 200-350 20 kg of concentrated sulfuric acid, calculated as 96% by weight of sulfuric acid. Use according to claims 1-4, characterized in that the mixture further comprises up to 2% by weight, based on the total weight of added water, mineral acid and nitrogenous fertilizers, of additives comprising trace metals selected from zinc, manganese, aluminum, magnesium, copper and iron, and / or dyes. Use according to claims 1-5, characterized in that a) the contents of the slurry tank are thoroughly stirred and the mixture according to claims 1-5 is added, after which the improved slurry is thus dispensed on the same day or no later than the next day, or b) the mixture according to claims 1-5, is filled into the slurry, after which the slurry is filled up and the slurry thus improved is released, or c) the slurry according to claims 1-5 during slurry is added to the slurry in the slurry distribution system, in all cases 1-5 kg and preferably 3-4 kg of the mixture according to claims 1-5 per day are used. 100 kg slurry. 7. Slurry product with reduced ammonia evaporation, characterized in that it comprises conventional slurry, in particular pig slurry or cattle slurry, to which, per 100 kg of slurry is added 1-5 kg, and preferably 3-4 kg of a mixture as defined in claims 1-5. Process for the preparation of a manure product according to claim 7, characterized in that a conventional manure, such as pig manure or cattle manure, is produced. 100 kg slurry puts 1-5 kg, and preferably 3-4 kg, of the liquid slurry enhancer as defined in claims 1-5.