2019 Year 12 IB Extended Essays

Why use hydroponics rather than growing the plants in soil? When I attempted the experiment using the soil, I noticed that depending on where the sample was collected, the data changed despite being collected from the same sample at the same time. Therefore, the experiment needed to be adapted, choosing to use hydroponics as the nitrates are evenly distributed in the solution, enabling me to accurately collect data. There are also no additional additives present whereas in soil, there is a range of different chemicals present. The only factors that will be changed in the hydroponic set up will be the nitrate levels of the water along with salinity. Purpose The purpose of this report is to determine the viability of using Greywater to flush out salt from farming soil. By conducting an experiment to determine the tolerance levels of plants to salinity and nitrate, it would be possible to gauge how much salt should be flushed from the soil and also be possible to determine the level to which the greywater should be diluted to make the growth of crops viable. Freshwater is sparse in Australia and using it to remove the high salt levels in farmland will be wasteful. On this front, this controlled experiment was developed to specifically determine the impact of nitrates on crops and the impact it would have when compared to the salt that it is attempting to replace and to what extent the greywater will be need to be diluted to reduce the potential impact of excess nitrates. As the experiment is being controlled, the impact of other factors such as chemicals and grease won’t considered.

4