Ammonia and methane reduction with new design liquid-tight floor

By keeping urine and faeces separate in the barn as much as possible, the discharge can be reduced. Ammonia is formed by the fusion of manure and urine: The urea in the urine is converted to ammonia by urease, which is found in faeces. Researchers from Wageningen Livestock Research (WLR) have tested a new design of a liquid-tight floor on the Dairy Campus in Leeuwarden for functionality and emission reduction potential.

By separating manure and urine by means of a sloping floor, a manure robot and a drain for urine, the formation of ammonia is prevented and the discharge is therefore reduced. The floor has the potential to reduce both ammonia and methane emissions – which is the purpose of the Integrated Approach program.

Properties of the examined floor

The examined floor consists of a gas and liquid-tight perforated plate profile and is provided with a non-slip layer with polyurethane coating. Urine can flow out via a drainage drain with a slope of 1.5 percent to a closed collection, the feces are collected by a modified fertilizer robot.

For structural cleaning of the surfaces, the drain gutter is equipped with a spray rod, the fertilizer robot with a hydrogen vacuum cleaner, a reservoir for collecting the rinsing water and ten spray nozzles at the bottom.

Research and results

To test the function of the barn design, the separation mechanism and the fertilizer robot, various measurements and observations were made. The efficiency of the drainage of urine, the function of the slurry robot, the emissions per2the urease activity, the soiling of the floor, the cleaning mechanisms and the walkability of the floor.

In principle, daily fresh manure and urine were used for the stool and urine tests. 85% of the urine is drained directly through the drain. 62 percent of the feces were collected by the robot for the first time, 11 percent ended up in the rinsing water. Emissions from the floor (CH4CO2NO2NH3) and the urease activity is lower after cleaning with the robot, but it is important that the robot continues to clean and does not leave a fertilizer film. This turns out to be a difficult point.

It was striking that the robot mainly left manure in the bends, even after the second round of cleaning. Urea activity was minimal on the clean floor, but again, it is important that no fertilizer film remains. The walkability is tested with two cows and is sufficient, but reinforcement of the floor is desirable to be prepared for possible point loads.

Future perspective on this floor

The design of a liquid-tight floor may have perspective, but there are still practical points of attention that prevent emission reductions from being achieved in practice. For maximum efficiency, the robot must work continuously, but battery life, water consumption and water storage are currently insufficient for this. Without a solution to these points, the floor will not be a success.

It should also be noted that the results are based on a test setup and the test conditions were not always ideal. As a result, these results may differ from the application of this system in practice.

Floor tiles and rubber floors can also lead to higher emissions

Other emissions studies have shown that innovative solutions such as floor tiles and a rubber floor can also lead to higher emissions than with a conventional slatted floor. The low-emission solutions can in certain circumstances have the opposite effect, for example due to wear and retention of manure and urine.

The usefulness of rinsing has already been demonstrated in other research. Regular rinsing resulted in an ammonia reduction of about 40 percent. The consequence is that the amount of manure increases as a result.

Recommendations for ongoing research

It is recommended for the ongoing research to carefully consider whether the system can be made robust, and to test the desired adjustments in a new test set-up before testing the floor in an entire barn with cows. A big advantage of this floor is that it can be built into existing stables. In addition, the direct and permanent separation of the two fertilizer streams makes it possible to process them separately into fertilizer products for targeted application or further processing.

This practical research entitled ‘Innovation and development in the separation of faeces and urine in stables for dairy cattle and pigs’ has been carried out in connection with the Integrated Approach program and is funded by the Ministry of Agriculture, Nature and Food Quality.

Source: Integrated approach

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