Introduction

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In our experiment for the Environmental Science Summer Research Experiments for young women, we tested the effect of leaching on an environment to see the effects of pH and iron. Iron is a very significant and essential element in the environment and is identifiable in the soil by its rusty red or orange color (O’Reilly, 2002.  While only about five percent remains on the Earth’s outer layer, it is essential to almost every living thing for various reasons (Lenntech Water Purification and Air Treatment Holding BV, 2006)  Its ferrous iron form is essential to plant growth because it is essential in the production of chlorophyll, which in turn  is significant because it is necessary for photosynthesis.  (K State Research, 2003).  However, the most plentiful form of iron in the soil is ferric iron, and ferric iron compounds cannot be absorbed by the roots.  The pH of soil determines which form of iron is present, with ferrous iron available in acidic soil and ferric iron available in basic soils.  Hence as the soils pH rises, plants must struggle and generally do not succeed in using the iron as effectively.  Zinc, pH, Phosphate, Copper and Manganese are also all very influential in dictating the various iron amounts (Plank and Lee, 1989).  But pH is the dominant factor.  As soil pH increases the ferrous iron becomes ferric iron.

   One key factor that influences soil pH, and consequently iron levels is the process of leaching. Leaching is the process of washing away nutrients and other dissolvable substances from soil by adding large amounts of water to the soil.  The factors that influence leaching are temperature, the setting, and the solvent. Temperature influences leaching because it allows for materials to dissolve at different rates. The setting influences leaching because the environment varies based on it’s features.  In nature, the features of an environment that vary when leaching are the soil texture and the plants. Based on how dense the soil, the water would absorb at a different rate. Depending on the types of plants and the amount of plants in an area, it could effect how fast the water is absorbed. The solvent that you use when leaching is an influence because different liquids and solids dissolve things at different rates. Water is usually the main solvent when leaching soil.

We decided to experiment with different water levels after researching iron in the environment.  We found that the most iron-rich soils are the densest ones, such as rice fields and swamp lands.  In context with the previously completed biota surveys, this made sense, because there were high iron levels in the dampest part, even though the pH was relatively high as well.  Our hypothesis dealt with discovering if the iron levels would get progressively lower as we added more water, forcing the iron deep down into the soil. 

Throughout our experiment, we learned many things about Iron, pH, and Leaching. We had fun doing the chemical tests and found many things interesting. We discovered plants and organisms that we had never heard of before. We also learned that  ninety percent of all living things live in the first 15cm of our earth! Also we learned that when you bake something such as soil, all of the nutrients goes on hold since there is no water. After adding the water back into the bags, the soil picks up where it left off.

    You could use an experiment such as this when you are trying to figure our why plants turn yellow or a brownish color. Because iron helps with the production of chlorophyll, when there is too much iron it decreases the pH causing the plants to go into a wacky cycle. When this cycle occurs the plants turn a yellowish brown.