Mount St. Joseph Future Scientist Award

Humans have been using fertilizer for centuries. But can fertilizer actually have negative effects? The main question being asked is how phosphates and nitrates affect plant life; and how nitrate levels can be reduced? The main hypothesis being tested is if different concentrations of phosphates and nitrates are introduced to mung bean plants, then the 4% concentration of each will result in the greatest height; and if solutes of soil, alcohol, and water conditioner are added to pond water, then the conditioner will help reduce nitrate levels the most.

Two main experiments were performed. In the first, different concentrations of potassium phosphate monobasic or potassium nitrate are given to mung bean seeds, and height of each plant combination was measured for comparison. It was seen that in reality the control mung beans (that were given solely water) fared better than those that were given the phosphates and nitrates in terms of height. It was also seen that the phosphate plants were taller and had more vitality than nitrate plants.

In the second, different concentrations of various solutes (soil, water conditioner, and alcohol) were put into pond water and resulting statistics (pH, nitrate, nitrite, alkalinity and hardness) were measured. It was proved that water conditioner (used commonly to denitrify) reduced nitrate levels but greatly increased alkalinity and pH levels. A solute of soil resulted in the highest nitrate levels.

Experiment 1: Effect of Potassium Phosphate monobasic and Potassium Nitrate on growth of plant life

Hypothesis:

If different concentrations of potassium phosphate monobasic or potassium nitrate are given to mung bean seeds, then the 4% concentration of each compound will result in the greatest height and vitality of the mung bean plant.

Background Information:

• The main ingredients in common plant fertilizer are nitrogen, phosphorus, and potassium, respectively.
• An excess of any material, whether compound, element, or medicine can be detrimental.
• Potassium Phosphate Monobasic has a molecular formula of KH₂PO₄ and Potassium Nitrate has a molecular formula of KNO₃.
• Mung Beans sprout 4 to 5 days

Controls:

• Two bean seeds will be put into each cup. Cups will be placed at same location
• The type and amount of soil will stay constant throughout experiment
• The size and material of cups will stay constant
• One cup (out of six) for Potassium Phosphate monobasic and one cup (out of six) for Potassium Nitrate will be solely a control; and will only have water with no compound
• Bean seeds will be taken from same source. They have same size, color, and type. Water will be taken from same source
• The same amount of water (with solute) will be added to the plants every night at same time.

Independent Variable:

Concentration of Potassium Phosphate monobasic or Potassium Nitrate in water being given to plants

Dependent Variables:

Height of plant measured after 13 days (in cm). Also, qualitative factors will be considered such as plant color before and after treatment.

Materials:

• 16 grams of Potassium Phosphate monobasic
• 16 grams of Potassium Nitrate
• 8 paper cups
• 16 mung bean seeds
• 1000 mL tap water
• Sharpie Marker

Procedure:

1. Fill 8 cups with the same amount and type of soil
2. Plant three similar beans 1 centimeter deep in each of the pots
3. Obtain 4 similar cups and similarly label them 1-4
   1. Add 2%, 4%, 8% of Potassium Phosphate Monobasic on each of the first three cup. One cup will be a control and will only get tap water.
4. Obtain 4 similar beakers and similarly label them 5-8
   1. Add 2%, 4%, 8% of Potassium Nitrate on each of the first three cups. One cup will be a control and will only get tap water.
5. Measure height of plants for 13 days
6. Also, keep qualitative records with plant color and angle of plant in relation to ground.

Results:

	Control KNO3	2% KNO3	4% KNO3	8% KNO3		Control KH2PO4	2% KH2PO4	4% KH2PO4	8% KH2PO4
Day 1	0	0	0	0		0	0	0	0
Day 2	0	0	0	0		0	0	0	0
Day 3	0	0	0	0		0	0	0	0
Day 4	0	0	0	0		0	0	0	0
Day 5	0.2	0	0	0		0.3	0	0	0
Day 6	0.5	0.3	0.25	0		0.5	0.3	0.3	0
Day 7	0.78	0.5	0.45	0		0.9	0.4	0.65	0
Day 8	1	0.75	0.75	0		1.3	0.5	0.85	0
Day 9	2.1	1.3	0.9	0		2	1.45	1.8	0
Day 10	5	2.1	1	0		4.5	2.4	4.3	0
Day 11	6.2	3.3	1.1	0		5.1	2.5	4.8	0
Day 12	6.9	4.1	1.1	0		6	2.7	5.8	0
Day 13	8	4.4	0	0		7	5.4	6.7	0

Data Analysis:

Generally, the addition of 2%, 4%, 8% of KH2PO4 or KNO3 to the mung bean plants greatly affected the height and growth of the plants.

As per the KNO3, the results were quite obvious. First and foremost, after 12 days, the KNO3 control had a height of 6.9 cm, the 2% concentration had a height of 4.1 cm, the 4% concentration had a height of 1.1 cm, and the 8% concentration had a height of 0. In this case, there was a direct relationship — as the concentration of KNO3 increased, the height of the plants decreased. The 8% concentration obviously killed the seeds because they never sprouted. And the 4% concentration also grew very sluggishly; after 11 days it too died –it was also very brown and lacked vitality. Surprisingly, the control (that was given only water) fared much better than the other three plants (that were given a solute in addition to water) in terms of height.

As per the KH2PO4, the results were less obvious than the KNO3. First and foremost, after 13 days, the KH2PO4 control had a height of 6.0 cm, the 2% concentration had a height of 2.7 cm, the 4% concentration had a height of 5.8 cm, and the 8% concentration had a height of 0. Again, the 8% concentration obviously killed the seeds because they never sprouted. However, the 4% concentration plant was almost double the height of the 2% plant but still shorter than the control. Overall, however, the phosphates performed better than nitrates in terms of height; therefore, fertilizers containing more phosphate than nitrate should be the most effective.

Conclusion:

The main ingredients in plant fertilizer are usually nitrogen, phosphorus, and potassium. And today, the general consensus will say that fertilizer helps plants grow. However, the results of this experiment go against this theory. In all cases, the control fared better than all other combinations in terms of height.

However, only three concentrations of solute were tested; the concentration added to some fertilizers might be different from the ones tested—it may be less or even more. This postulate is apparent in the tests with the KH2PO4; the 4% concentration plant probably fared better than the 2% and 8% because it is most beneficial to mung beans.

Furthermore, according to How Stuff Works article, “Does fertilizer help or hurt my lawn?” “When too much nitrogen is introduced to the soil, the plant works overtime on top growth, taking energy away from root growth and overall plant health.” This means that too much KNO3 or KH2PO4 was probably used in this experiment. However, this experiment does exemplify the results of overused fertilizer. It also proves that fertilizer with more phosphorus than nitrogen should be most effective.

Nevertheless, the hypothesis that if different concentrations of potassium phosphate monobasic or potassium nitrate are given to mung bean seeds, then the 4% concentration of each compound will result in the greatest height and vitality of the mung bean plant was rejected. The controls obviously grew taller than the 4% concentration.

Sources of Error:

Every experiment has sources of error and this one is no different. Every effort to give exactly the same amount of solution to its respective plant cup was taken; however, there is always human error and at times some plants may have received more solution than others. Also, some of the water in the solutions may have evaporated therefore making the concentrations more than 2, 4, or 8 %. In addition, although the main ingredients in fertilizer are nitrogen, phosphorus, and potassium, in this experiment, potassium phosphate monobasic and potassium nitrate were used; this may have skewed results.

Future Uses:

The implications of this experiment are phenomenal. Today, fertilizer is the cornerstone of everyone’s front yard; without it our yards would be yellow wastelands. Yet every year people complain that fertilizer “ruined” their lawns. Many have even come to doubt whether fertilizer actually promotes growth. What may be the cause of this? The answer is obviously the overuse of fertilizer. This experiment greatly exemplifies the results of the overuse. It also shows that fertilizers with majority of phosphorus should be more effective than fertilizers with majority of nitrogen.

Experiment 2: How can nitrate levels be reduced?

Hypothesis:

If soil, alcohol, or water conditioner is added to pond water, then the water conditioner will help reduce nitrate levels the most.

Background Information:

• High nitrate, nitrite, pH, hardness, or alkalinity is harmful to any life form
• Bacteria in the soil can help lower nitrate levels.
• Water conditioner is a liquid sometimes used to reduce nitrate levels in fish tanks.
• Pond water rather than tap water simulates a natural environment
• Repeating an experiment reduces variability.
• Statistics in this experiment means pH, nitrate, nitrite, hardness, and alkalinity
• Different concentrations often result in different results.

Controls:

• All cups will be similar
• All pond water will be taken from same place in pond
• The same test kit will be used for each test
• Same type of alcohol, soil, and water conditioner will be used
• Same amount of water will be added to each cup (195mL)
• Same amount of soil, alcohol, and conditioner will be added at the same time

Independent Variable:

Concentration of soil, water conditioner, or alcohol being added to pond water.

Dependent Variable:

Nitrate, nitrite, pH, hardness, and alkalinity of the water after treatment.

Materials:

• 6 similar cups
• 5-n-1 test kit that tests pH, nitrate, nitrite, hardness, and alkalinity
• ¾ gallon of pond water
• ½ cup of ordinary soil
• 5mL spoon
• Bottle of fish water conditioner
• 70% isopropyl alcohol

Procedure:

1. Label cups 1-6 and add 195mL of pond water to each cup.
   1. Take statistics (nitrate, nitrite, pH, hardness, alkalinity) of each cup and record
2. Add 2 teaspoons (10mL) of soil to cup 1 &2, 2 teaspoons of alcohol to cup 3 & 4, and 2 teaspoons of water conditioner to cups 5 & 6.
   1. Take statistics of each cup and record
3. Now, add 10 mL more of same substance to the same cup (total of 4 spoons)
   1. Take statistics of each cup and record
4. Now, add 10 mL more of same substance to the same cup (total of 6 spoons)
   1. Take statistics of each cup and record

Results:

Data Analysis:

Although nitrate levels are the main thing being measured in this experiment, nitrite levels, pH, hardness, and alkalinity was also measured for further comparison.

Nitrate:

With a solute of soil, the nitrate levels gradually increased from 10 ppm (in the control) to 20 ppm (in a 30 mL concentration of soil in 195 mL of water). With a solute of alcohol, the results were dispersed but overall, the nitrate levels decreased from 10 ppm (in the control) to 4 ppm (in a 30 mL concentration of alcohol in 195mL of water). With a solute of water conditioner, the nitrate levels gradually decreased from 10 ppm (in the control) to 3 ppm (in a 30 mL concentration of conditioner in 195 mL of water).

Nitrite: 

With a solute of soil, the nitrite levels gradually increased from 0 ppm (in the control) to 1 ppm (in a 30 mL concentration of soil in 195 mL of water). With a solute of alcohol and water conditioner, the nitrite levels were constant at 0 ppm (in the control) and (in a 30 mL concentration of alcohol in 195mL of water).

pH:

With a solute of soil, the results were dispersed but overall, the pH increased from 7.2 (in the control) to 7.9 (in a 30 mL concentration of soil in 195 mL of water). With a solute of alcohol, the results were also dispersed but overall, the pH stayed constant around 7.2 ppm (in the control) and (in a 30 mL concentration of alcohol in 195mL of water). With a solute of water conditioner, the pH gradually increased from 7.2 (in the control) to 11 (in a 30 mL concentration of conditioner in 195 mL of water).

Hardness:

With a solute of soil, the hardness slowly decreased from 300 ppm (in the control) to 190 ppm (in a 30 mL concentration of soil in 195 mL of water). With a solute of alcohol, the results were dispersed but overall, the hardness decreased from 300 ppm (in the control) to 160 (in a 30 mL concentration of alcohol in 195mL of water). With a solute of water conditioner, the hardness quickly decreased from 300 ppm (in the control) to 0 ppm (in a 30 mL concentration of conditioner in 195 mL of water).

Alkalinity:

With a solute of soil, the alkalinity quickly increased from 180 ppm (in the control) to 300 ppm (in a 30 mL concentration of soil in 195 mL of water). With a solute of alcohol and water conditioner, the alkalinity gradually increased from 180 ppm (in the control) to 360 ppm (in a 30 mL concentration of alcohol in 195mL of water).

Conclusions:

Soil:

The original idea being tested is whether soil can denitrify. But this experiment demonstrated that this cannot be done; the nitrate levels increased substantially. In addition, pH, nitrite levels, and alkalinity all increased as the concentration of soil increased. Only hardness decreased. This demonstrates the ineffectiveness of solely soil not only to reduce nitrate levels but to keep plants from dying. This proves that bacteria in soil cannot denitrify and that some other fertilizer or conditioner must be used in addition to soil to denitrify.

Alcohol: 

The alcohol did indeed reduce nitrate levels. However, it is too impractical to be useful in everyday life. As the concentration of alcohol increased the pH and nitrite levels stayed fairly constant and the hardness decreased. However, the alkalinity increased almost two fold from the control. High alkalinity levels are very harmful to any life form. However, alcohol may be a reasonable solute to use with non-living things.

Water Conditioner:

Water Conditioner is made to reduce nitrate levels (and other harmful toxins) and this is demonstrated in the experiment. Nitrate levels and hardness were reduced dramatically as more conditioner was added. However, pH and alkalinity dramatically increased as concentration increased. Water conditioner completed its job by reducing nitrate levels but caused problems that can be classified as more severe. Today water conditioner is used in fish tanks all around the world; however, almost nobody knows that by using it, pH and alkalinity are both gradually increasing. This experiment demonstrates that at times, putting water conditioner in a fish tank can be as harmful as putting alcohol in the same. Using alcohol resulted in more standard statistics than from using water conditioner.

Nevertheless, the hypothesis that if soil, alcohol, or water conditioner is added to pond water, then the water conditioner will help reduce nitrate levels the most was confirmed but only just. Even though the water conditioner reduced nitrate more than any other solute, it increased both pH and alkalinity greatly. Alcohol on the other hand, reduced nitrate levels and increased alkalinity but pH stayed constant.

Sources of Error:

This experiment like all others had many sources of error. First, the scales used to measure nitrate, nitrite, pH, alkalinity, and hardness were not exact; they were not professional and therefore not as accurate as possible. Also, when comparing the color on the scale to the color chart provided, there may have been human error. There may also have been human error in measuring amount of solute to add to the pond water.

Future Uses:

High nitrate levels are a major problem in many aquariums and gardens. High levels can prove to be deadly; therefore, there needs to be some solute to reduce these levels. This experiment proves the ineffectiveness of using water conditioner because it increased alkalinity and pH. Also, many people simply use soil (and let nature run its path) to denitrify; this experiment proves that solely using soil can be detrimental – one must use a solute in addition to soil to keep a garden in the best condition.