A farmer applies 1500kg of fertilizer that contains 10% nitrogen to his fields each year. 15% of the fertilizer washes into a stream that runs through the farm. If the stream flows at an average rate of 1.4 cubic meters per minute, what is the additional concentration of nitrogen (expressed in mg nitrogen per L) in the stream water due to the farmers yearly application of fertilizer?

Question

kg1975 · Answer

15% of this runs off = 22.5kg EACH YEAR.

How many minutes in each day? 60mins/hr * 24hr/day * 365.25days/yr = 525960 minutes/year

1.4cubic meters per minute * 525960 = 736344cubic meters of water * 1000 = 736344000LITRES

if you dilute this with 22.5kg of Nitrogen:

22500g/736344000litres = 0.0000305g/litres = 0.0305mg/litre.

Bang :)