RIVM: amount of nitrogen and phosphate in farm ditches doubled | Inland

First, the amount of nitrogen and phosphate (both nitrates) that got into the soil on farms increased, according to the RIVM. In 2017 there was an increase in ditch water around the farms. According to the RIVM, this is partly due to increased emissions and partly due to drought in the summer. “Due to the drought, crops absorb less nitrogen and phosphate. The resulting surplus then partly washes out to the surface and groundwater. “

For the time being, the increase has been limited to ditches. On average, the nitrate concentrations in Dutch ground and surface water in the period studied decreased compared to the previous four years.

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Nitrogen and phosphate are found in manure, among other things. High concentrations in ditch water can, for example, lead to proliferating blue-green algae and duckweed. Blue-green algae is poisonous and biodiversity can also decrease if some species start to proliferate at the expense of others. Another effect of too many pollutants is that drinking water companies have to make an increasing effort to remove them from ground and surface water, according to RIVM.

According to the report, water quality in the Netherlands has improved for decades, mainly because farmers started using less and more careful manure. However, this improvement is progressing at a slower pace, while in many places concentrations of nitrates are still being measured.

The top meter of groundwater contains too much nitrogen and phosphate on more than half of the farms in sandy and loess areas. The concentrations of nitrates in the top layer of groundwater are also too high in some 30 of the approximately 200 groundwater protection areas that are important for drinking water supply. “It is uncertain whether current policy is sufficient to achieve the objectives,” RIVM concludes.

Last summer, the Central Bureau of Statistics (CBS) reported that the excretion of phosphate and nitrogen on farms decreased in 2019, by 4 percent and 2.8 percent respectively. This was mainly due to the decrease in the number of dairy cows.

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