Ten dairy farmers in the peatland region of the Netherlands are studying the possibilities of reducing the amount of ammonia emitted by their companies by 25 per cent at no extra cost. By closing leaks in the nitrogen cycle, they use less concentrate and artificial fertiliser without harming milk production. They also deploy manure more efficiently on the land; for example, by diluting it with water. From the start of 2017, the ten farmers have been joined by another 90 colleagues who are putting the lessons learned in the first year into practice.
The first step in this peat testing ground is to make the dairy farmers aware of the cycle of the nutrients nitrogen and phosphate,
says Koos Verloop, expert in sustainable grassland management at Wageningen University & Research. “The farmers feed their cattle grass from their own land. Part of the minerals is lost via their milk and meat, and a large percentage of the nutrients is excreted via the manure and thus returned to the peatland.”
The unfortunate fact is that nutrients leak out into the environment. Nitrogen escapes from sheds into the air as ammonia and ends up in nature areas. In addition, nitrogen from the land flows into the surface
water. “The goal is to close the cycle of nutrients in feed, manure, soil,
grass and feed again as much as possible,” says Verloop.
Reducing nitrogen losses
Together with Michel de Haan of Wageningen Livestock Research, Verloop looks at the ways farmers can reduce nitrogen losses. “The first is to reduce the amount of protein in roughage,” Verloop continues.
“Peatland grass has a relatively high percentage of protein due to the
mineralisation of nitrogen in the peat, so extra additives such as brewer’s
grain can be cut back,” De Haan adds.
The second way is related to the first: using less artificial fertiliser and applying it at smarter times during the growth season. “This would save farmers money as well,” says De Haan. The third method is also
profitable. Letting the grass grow for an extended period and grazing the
cattle in a smarter way reduces nitrogen levels in the grass and the percentage of protein in the feed. “It can also save farmers one mowing session by a contractor,” De Haan clarifies.
Mix of measures
The testing ground is also being used to study the effectiveness of the fourth method: growing grass with a lower nitrogen percentage or feed cattle grass from herb-rich grasslands, such as English plantain. In addition, there are two ways to reduce leakage via manure. The first is to work the manure into the ground more thoroughly, allowing less
ammonia to escape. “This can be achieved by supplying the manure from the shed via hoses and diluting it with water from the ditch. This would also reduce transport costs for the farmers,” De Haan believes. Finally, farmers can build sheds with low-emission floors and insulated roofs, Verloop adds.
Each farmer should choose the mix of measures that suits his company best. “The tool we provide, the so-called KringloopWijzer (cycle adviser), provides insight into the nitrogen streams and leakages of each company.” The scientists think that awareness of the measures for success will quickly grow. “And don’t forget the impact of concentrate suppliers,” says Verloop. “They visit all farmers and explain about how things are changing at their neighbours.”
The study will take three years and receive an annual subsidy of one million euros from the Province of South Holland, the Dutch Ministry of Economic Affairs and LTO. The great thing about this integrated
approach is the additional benefits it offers in other areas too. It will
result in less nitrogen flowing from the grassland, which improves the quality of the surface water. Moreover, as less water is pumped out, less peat will oxidise, which in turn reduces soil subsidence.
An important factor related to the awareness and motivation of the dairy farmers is the focus on other sources of nitrogen emissions in the area, such as Schiphol Airport or the Port of Rotterdam. “After the emission reduction has proven successful, they may be willing to pay farmers for nitrogen emission allocation,” concludes de Haan.