2019 Year 12 IB Extended Essays

Conclusion: Flushing the saline soil with greywater is viable when taking the results of this report into account but there are some factors that need to be considered before doing so. It must be ensured that the greywater that is used doesn’t have a nitrate concentration over 0.4381M. If this concentration is crossed, the beneficial effects of nitrates on plant growth could begin to reduce and eventually cause the cells of the plant to get plasmolysed. This effect is similar to that caused by excess NaCl. If the concentration is over 0.4381M, then the greywater will need to be diluted prior to being used. The report also demonstrated that the impact that salt had on plant growth wasn’t completely negative and by diluting the soil salt levels to a concentration of 0.0068M, the plants are able to grow at their optimum rate. It must however be noted once more that this controlled experiment only took into consideration the impact that the nitrates within greywater had on plant growth and didn’t consider other factors.

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