Less nitrogen and phosphate excretion from livestock manure

In 2021, nitrogen excretion from manure produced by cows, pigs, poultry and other livestock amounted to 471.0 million kg. This is 33.4 million kg below the production ceiling of 504.4 million kg. It is the fourth consecutive year Dutch nitrogen excretion levels fell below the production ceiling. Since 2017, the amount of nitrogen excreted by the national herd has decreased by 41 million kg. The largest contribution to this reduction (30 million kg) has come from dairy holdings, particularly as a result of cow and young stock herd reductions. Despite declining nitrogen production from 2017 onwards, the Dutch cow herd still exceeds the level of 2010 by over 7 million kg. Over the same period, nitrogen production from pig manure decreased by 17 million kg and from chicken manure by 10 million kg.

Last year, phosphate excretion fell by 2.7 million to 148.0 million kg, putting the amount well below the production ceiling of 172.9 million kg.

Nitrogen excretion by dairy cattle below ceiling

Last year, dairy cattle and accompanying young bovines excreted 273.0 million kg of nitrogen, i.e. 4.7 percent less than in the previous year. This brought nitrogen excretion by the dairy sector under the production ceiling of 281.8 million kg for this sector. Up to 2015, the size of the dairy herd was limited by the milk quota system. After this system was abolished, herd growth was halted by the implementation of a phosphate rights trading system. Last year, the dairy sector remained below the nitrogen production ceiling for the second time since 2015.

At 74.2 million kg, phosphate excretion by the dairy sector has remained well below the ceiling of 84.9 million kg. Last year’s production was 0.5 million kg up on 2020.

The fact that nitrogen production in the dairy sector decreased while phosphate production rose slightly is linked to the cattle feed composition, which contains grass and maize silage. Last year, the grass silage in the feed partly consisted of grass harvested in 2020, while some of the grass was harvested in 2021. The part harvested in 2021 had a low nitrogen content, resulting in a lower average nitrogen production level. On the other hand, this grass had a relatively higher phosphorus content.

Less nitrogen, more phosphorus in dairy cattle feed

Excretion levels of nitrogen and phosphorus in manure from dairy cattle and other grazing livestock are highly dependent on the grass and maize silage content of the feed. In the period 2017-2020, weather conditions resulted in a relatively high nitrogen content but a low phosphorus content of the grass silage. Furthermore, the availability of maize silage (which has a relatively low nitrogen content) was limited due to shrinkage of the maize cultivation area in that period. Then, in 2021, the feed contained less nitrogen on account of using grass silage with a lower nitrogen content combined with a larger share of maize silage, while the phosphorus content of the feed rose due to a higher phosphorus content in the grass silage.

Pig and poultry manure produced less nitrogen and phosphate

Nitrogen and phosphate excretion levels in the pig herd and poultry herd are largely related to herd size. These animals are not fed roughage but mostly compound feed with a fairly stable composition. Over the past five years, herd reductions have led to a continued decline in nitrogen and phosphate excretion from pig and poultry manure.

In the pig sector, nitrogen production fell by 2.9 million kg (3.2 percent) last year, to a total of 88.9 kg. Phosphate production decreased by 2.2 million kg to 34.5 million kg. In both cases, the decrease was related to the reduced size of the pig herd. The pig herd reductions are partly the result of a buy-out scheme for livestock farmers to control ammonia emissions and a subsidy scheme for the remediation of pig farms (SRV). Since 2016, both nitrogen and phosphate excretion by the pig herd have remained below the respective production ceilings for this herd.

In the poultry sector, nitrogen excretion dropped by 0.7 percent and phosphate excretion by 3.7 percent. Last year, nitrogen production stood at 54.3 million kg and phosphate production at 23.2 million kg, both remaining below the applicable ceiling.

As for other livestock, nitrogen production decreased last year by 0.9 million kg (3.9 percent) to 21.9 million kg. The decrease was entirely attributable to the ban imposed on mink farming as of 1 January 2021.