Saturday, September 25, 2010

Nitrate: The second sweetcorn plot

The wetting front detectors were installed deeper in the second plot - at 30 and 50 cm instead of 20 and 40 cm as in the washing machine plot.
The second corn crop (with NaCl added to the water) also had a lot of nitrate in the soil before any fertiliser was added, with over 700 ppm nitrate recorded by week 4 (above).
This time more nitrate was recorded in the shallow detector (which in this case was at 30 cm depth). In the washing powder plot, most of the nitrate was in the deeper 40 cm detector (top graph).
Such high levels of nitrate meant that no more additions of nutirents were reqired. Once again it was important to manage the irrigation so as not to leach the nitrate out of the root zone.

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