2019 Year 12 IB Extended Essays

The crops weren’t grown in soil like regular crop plants would be. Grey water is made up of more than just nitrates

Systematic This would significantly affect the data being collected as the effects of

Conduct the same experiment using soil samples mixed with different concentrations of NaNO3 rather than using cotton Conduct the same experiment using the greywater from a 80L washing machine to see the impact that greywater on its own has on plant growth.

different microorganisms present in the soil on the growth of the plant would be significant and wasn’t being considered in the experiment.

Systematic If greywater was to be used in the experiment in a real-life scenario, it would have other nutrients and

materials which could negatively affect crop growth depending on where the water is sourced. As the end goal was to determine the potential use of greywater to dilute high salt levels, if the impact of these chemicals on the plants were not considered, then it becomes difficult to justify using greywater.

Extension: The concentration of the NaNO3 solution could have been increased further to determine the impact the excess Nitrates has on the growth of the plant and on the qualitative features of the plant. It would also be good to determine whether the increase in Nitrate concentration causes a decrease in the size of the roots, similar to the occurrence in the 0.1095M NaCl solution. The experiment could have been conducted over a period of 60 days to determine the impact that having no nutrients in the soil has on the growth of the plants grown pure distilled water and whether the plant grown in 0.0068M NaCl will continue to grow taller or whether the data expressed in the report was affected by errors.

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