E03: Oak

Analysis on the Effects when using Different Concentrations of Nitrogen in Potting Soils to Determine the Growth of Alfalfa sprouts (Medicado Sativa) , using Height and Length (from Hypocotyl to Radicle)

R.Oak

AP Biology Periods: 1

Miramonte High School, Orinda, California

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Abstract

I decided to grow 5 alfalfa sprouts, with decreasing levels of nitrogen in the soil. Nitrogen helps plants grow and allows them to form genetic and structural compounds as well as chlorophyll. I hypothesized that the Alfalfa sprouts grown in the soil with the more concentration of nitrogen would grow larger. My results supported my hypothesis but I had some design errors and improved follow up experiments could be performed for better results.

Introduction

Nitrogen is extremely important in facilitating the growth of a plant. Nitrogen is absorbed through the roots and is one of the many chemical ingredients required for both plant growth and reproduction along with potassium, phosphorus, magnesium, and sulphur. Nitrogen is also a component of chlorophyll and is essential for photosynthesis. Additionally Nitrogen helps the plants with rapid growth, increasing seed and fruit production as well as increasing the quality of leaves and structure.(North Carolina Department of Agriculture).

Plants use nitrogen by absorbing either nitrate or ammonium through the roots, from the soil. Plants cannot use nitrogen from the air because is is in the molecule N2 and does not work, because for a plant to be able to process this nitrogen it has to be in the form of nitrate (NO3-) or ammonium (NH4+) . It is necessary for the nitrogen to be in these forms because it is easy for them to synthesize amino acids. Additionally plants can absorb Urea Nitrogen (Harper 1984).

Alfalfais a perennial plan in the pea family, and is a legume. legumes use nitrogen more than other plants so it was felt that this plant would truly demonstrate the importance of nitrogen. The results of this experiments are extremely important because they show avid gardners how the nitrogen content in their planting soil changes.

In the first trial had only .05 % nitrogen content in the fertalizer and therefor I expect it to grow the least amount when compared to the other trials. In the second trial the soil had .10 % of nitrogen so therefore it is expected that this trial will work better than the first. For the trial a soil with .15 % of nitrogen is used, and for the fourth trial we used .20 % of nitrogen. We expect the growth rate to increase as the concentration increases. for our positive control we attempted to grow a seed in saltpeter.

Materials

Material	Amount
Miracle Grow Potting Mix	7.5 L bag
spade	1
0.94 L quart pots	5
Nitrogen deficient soil	7.5 L bag
OTT- LITE	1 light
Black construction paper	9 sheets
Saltpeter	1 kg
Radiance HD Alfalfa  Seeds	1 Pack

Procedure

1. Set thermostat to 22.2’ C and wait for the house to warm

2. Clear space in bookshelf

3. Set up OTT-LITE inside the bookshelf to provide the alfalfa sprouts with a source of light

4. Open the package for the plastic pots and label which pot will house which soil type

5. Create the soil concentrations for the different types and open the saltpeter

6. Fill the pots with the different gradients of soil

7. Put the alfalfa seed ¼ inch into the soil.

8. place the pots into the bookshelf space

9. Seal the front of the Space with the black construction paper to stop outside interference

10. Water the sprouts every day at 7:00 PM with 10 ml of water and record any sprout activity

Setup

Figure 1: Setup of the experiment

Results

Chart:

These charts compare the heights of the plants that were grown over a 2 week period, using the same planting technique, and process for planting. (ex alfalfa sprouts, 22.2’C, for 2 weeks). The only difference between the trials is the concentration of the nitrogen in the soils. The plants were planted in soils with 0.5, 0.1, 0.15, and 0.20 % of nitrogen and the positive control was grown in 100% nitrogen . The plants were recorded a total of 14 times.

Figure 2: Height over time in centimeters from the hypocotyl to the radial of the sprouts in different concentrations of nitrogen

Soil type%	D1	D2	D3	D4	D5	D6	D7	D8	D9	D10	D11	D12	D13	D14
0.05	0	0	0	.5	.5	.8	1.0	1.1	1.5	1.8	2.1	2.4	2.5	3.0
0.10	0	0	.4	.5	.7	1	1.3	1.4	1.6	2.0	2.1	2.6	2.8	3.3
0.15	0	.5	.5	.7	0.9	1	1.5	2.0	2.1	2.3	2.7	3.5	3.6	3.9
0.20	0	.5	.7	.8	1	1.1	1.7	2.2	2.4	2.6	3.0	3.6	3.8	4.3
100	0	0	0	0	0	0	0	0	0	0	0	0	0	0

Graph:

Discussion

The results of the experiment support our hypothesis which was that as the concentration of nitrogen in the soil increases the growth and the height of alfalfa sprouts increases. This was shown in our graph because it was evident of this direct correlation between the increase in nitrogen and the plant height.

Over the course of this experiments there were many possible sources of error. When the plants were placed in the shelve, it was not certain that the temperature was exactly at the 22.2’C over the course of the time. Also it was impossible for the light to be properly distributed over all 5 of the trials. Also another factor might have been seed quality.

When a future experiment is performed it is critical to make the environment the same for all the experiments it is also critical to make the best soil with the most precise amount of nitrogen concentration in the soil.

Works Cited

Harper, F. L. "Element Concentrations in Soils and Other Surficial Materials of the Conterminous United States." USGS. USGS, n.d. Web. Nov.-Dec. 2013.

"Plant Nutrients." Plant Nutrients. North Carolina Department of Agriculture and Consumer Services, n.d. Web. 05 Dec. 2013.

"Plant Nutrients." University of Wisconsin Extention. University of Wisconsin, n.d. Web. 5 Dec. 2013.

"The Role Of Nitrogen In Plants." House Garden Nutrients RSS. House and Garden Van De Zwann, n.d. Web. 05 Dec. 2013.

"Soil Fertility Guide." Manitoba. Canadian Government of Manitoba, n.d. Web. 05 Dec. 2013.

"Soils - Part 5: Nitrogen as a Nutrient." Plant and Soil Sciences ELibrary. Plant and Soil Sciences ELibrary, n.d. Web. 05 Dec. 2013.