Denmark has among the strictest environmental laws covering farming in the EU. To see what it takes for Danish producers to meet these requirements, the UK’s Agriculture and Horticulture Development Board (AHDB) Pork recently arranged a field trip for a group of British farmers, veterinarians, researchers and others from the allied industries.
As AHDB’s Sue Rabbich and Nigel Penlington explained in a recent webinar, the aim of the visit was to investigate opportunities for integrating new technologies to improve farm efficiency and performance to meet the new regulations for reducing ammonia production, which have already been proposed and are undergoing a final review before coming into law in England.
Danish law already covers the need to minimize the escape of ammonia and odors from farms, which can be tackled through the design of the building and by using technology to reduce the pH of the slurry.
All farm buildings in Denmark require a permit — even grain stores — whereas in the UK, this only applies to larger farms. Furthermore, Danish farms need to be able to store slurry for up to 10 months, compared to six months in the UK, and there are lower limits on the rate of nitrogen application to the soil.
Reducing emissions starts with building design
“The low-energy hybrid ventilation system is the key feature of the new Intellifarm concept from Agrifarm, which can be used in buildings for pigs or cattle,” Rabbich said. “It helps reduce emissions of ammonia, dust and odor.”
The system is based on automatically controlled natural ventilation combined with fans to allow crossflow ventilation under the slatted floor, forming an “air curtain” to separate the smells and emissions generated in the slurry from the animals and people in the house. An air scrubber can be added to remove odor and ammonia from exhaust air, resulting in a lower environmental impact.
The design allows for the building to have a span of up to 65 meters for pigs (75 meters for cows). The building is tall, with a 2-tier roof with 2-piece side inlets and a second set of controlled inlets halfway up the roof. The wide outlet in the ridge of the roof maintains a healthy atmosphere for the animals, whatever the weather.
“The floors and bedding were very dry, offering good conditions for the animals and workers,” Rabbich commented.
Other advantages of the building she identified were its low energy requirement and low emissions, and it can be set up to be operated remotely from a computer, tablet or smartphone.
Two new typical pig houses on the tour, one still under construction, demonstrated that the walls are usually built from pre-cast concrete panels with an insulation layer between — vital for energy saving in Denmark, where the temperatures may remain low during prolonged winters. Another feature that helps save energy is that the incoming air first enters into the loft space under the roof, allowing it to warm up in winter before it passes through permeable panels into the main building space. The same process helps to cool the incoming air slightly in summer.
Slurry-treatment system improves resource efficiency
A slurry-treatment system to reduce its pH has been installed with these and other new buildings, improving resource efficiency by increasing the fertilizer value of slurry. It also reduces odors and ammonia by around 43% and 65%, respectively.
From a storage tank, a series of pumps and valves combine sulfuric acid with separated slurry in a covered mixing tank to achieve a stable pH of 5.5. They then return the mixture to the slurry tanks in the pig house to a depth of 18 cm. After 1 or 2 days, the whole process is repeated when the pH of the slurry under the building reaches pH 6. The final stage is when the slurry is separated to help odor reduction and separate insoluble nitrogen and phosphorus.
Controlled by a computer in the farm office, the system is totally automatic and requires no labour input once the system has been set up. In case of an accident, an outdoor shower is installed nearby.
Main benefits of pH reduction in slurry are much-reduced levels of ammonia and odor. As a result, there is no need to cover the main slurry store, representing a cost saving. Conditions are improved for pigs and staff and there are fewer flies. Furthermore, the acid treatment improves the quality of the slurry as a fertilizer, making the nitrogen and phosphorus components more available to crops, and it adds sulfur, reducing the need for other fertilizers.
As a rough guide to the economics of the system, the firm In Farm said the annual cost for a system suitable for 500 sows in Denmark would be around €23,000. It would generate a value of around €48,000 annually, mainly in terms of increased wheat yield.
“This system is a credible alternative to air-scrubbing to remove odor and ammonia,” Penlington commented.
Increasing labor efficiency with robotic systems
Better efficiency of labor is the main benefit of robotic systems. A small battery-powered robot running on an overhead track can distribute straw and sawdust bedding or hay, maize silage, sand and the fibre from separated manure, several times a day. The track runs from a filling station to the animals, unhampered by pen walls. There are several different spreader options to deliver the material to the floor (for straw bedding, as shown) or manipulable material into racks for sows, for example. The robot can move at a speed of between 2 and 30 metres per minute, up to 8 times a day and using up to 18 different tracks.
The system greatly reduces the labor required for such routine tasks as feeding and bedding down.
Summing up, Rabbich and Penlington said that farmers in Denmark are employing lower-impact housing systems to obtain permits to build and operate livestock farms. With grants available for some techniques that benefit the environment, there are a number of technologies available that improve efficiency, comply with legislation and reduce odor and ammonia from livestock buildings. And they can also contribute to the bottom line.
Watch the webinar: