Dairy Farming and nitrate pollution

Hey guys, today’s post will focus on dairy farming and its impacts on water pollution. I’ll like to rehash my previous post (on fertiliser use and nitrate pollution), because the biological activities of dairy animals like cows and goats can also cause nitrate contamination of groundwater, which is problematic because unlike in Singapore, groundwater is a ‘tap’ for other nation’s drinking waters.

My case study here will be Canterbury, NewZealand. Farming is the largest contributor to Canterbury’s economy and studies has shown that intensive dairy farming in the past 10 years has led to elevated nitrate levels in groundwater aquifers by 30% (Young, 2013). This increase is caused by the application of synthetic fertilizer such as Urea (contains 46% nitrogen) to animal pastures(Baskaran, Cullen and Colombo, 2009).

The high nitrogen content on the pasture, when consumed by the dairy animals such as cows, cannot be fully converted into protein and be stored in the cow’s milk. The animals will excrete these excessive nitrogen into their defecation and their wastes. 80% of the nitrogen consumed by the cow is then returned to the soil (Bgs.ac.uk, 2004).

When leaching and surface runoff occurs (from either rain or irrigation), the nitrogen in the pasture and in the excrement is leached into the soil layers as nitrate. As percolation happens, these nitrate is transported into the groundwater aquifers, contaminating the waters. As such, when the Canterbury people drink the nitrate-contaminated ground waters, they can develop a range of health effects including the Blue-Baby Syndrome, which I have discussed in my previous posts. Fortunately, only 11% of the wells in Canterbury have nitrate concentration exceed the Maximum Acceptable Value of 50 mg/L according to the New Zealand Water Drinking Standards (Environment Canterbury, 2013; Radio New Zealand News, 2013). Nonetheless, actions have to be taken.


From Group Project. This diagram shows the process of nitrate contamination caused by dairy farming; from its point and diffused sources, to the transport mechanisms, to the groundwater contamination, and finally to the health impacts on consumers of contaminated water. Pardon the poor resolution; this is the best i could do.

That’s all from me now.

My next blog post will be on dairy farming, the release of GHGs and its alleged Global Warming effects. So stay tune! 😀

Work Cited: 

Baskaran, R., Cullen, R. and Colombo, S. (2009). Estimating values of environmental impacts of dairy farming in New Zealand. New Zealand Journal of Agricultural Research, 52(4), 377-389.

Bgs.ac.uk. (2004). Water Quality Fact Sheet: Nitrate. [online] Available at: https://www.bgs.ac.uk/downloads/start.cfm?id=1276 [Accessed 4 Mar. 2015].

Environment Council. (2009). Drinking Water. Available at: http://ecan.govt.nz/publications/Plans/cw-regional-context-part6.pdf. [Accessed 4 Mar. 2015].

Environment Council. (2013). Risk maps of nitrate in Canterbury groundwater. Available at: http://ecan.govt.nz/publications/Reports/risk-maps-nitrate-canterbury-gw-r13-44.pdf. [Accessed 4 Mar. 2015].

Radio New Zealand News. (2013). High nitrate levels found in Canterbury wells. Available at: http://www.radionz.co.nz/news/regional/225364/high-nitrate-levels-found-in-canterbury-wells. [Accessed 6 Mar. 2015].

Young, R. (2013). Drinking water under watch. Available at: http://www.stuff.co.nz/the-press/news/canterbury/9357735/Drinking-water-under-watch. [Accessed 6 Mar. 2015].


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