Nitrate leaching by organic and inorganic fertilizers
The hypothesis that the runoff water of soil mixed with inorganic fertilizer will have highest nitrate content has been proven to be true.
The growing demand for biofuel has caused a boom in crop production and extended the use of fertilizers. Continual increased use of fertilizers is increasing the nitrate contamination of rivers and lakes and threatening the survival of fish and other living organisms. Nitrate contamination of groundwater can also cause health problems, such as the baby blue syndrome.
The science fair project may be repeated using different type of soils like clay, sand and loam.
The science fair project may also be modified to compare the nitrate levels of different types of organic and inorganic fertilizers.
Fertilizer - http://en.wikipedia.org/wiki/Fertilizer
Fertilizer runoff overwhelms streams and rivers - http://www.scientificamerican.com/article.cfm?id=fertilizer-runoff-overwhelms-streams
Selecting forms of nitrogen fertilizer - http://ohioline.osu.edu/agf-fact/0205.html