Exam (elaborations)

IB Biology IA

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IB Biology

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This IA got a raw score of 20/24, but was moderated down to 18/24, getting a 6 overall. I got a 7 for Biology overall. I did my Biology IA on nitrogen fertilizers and investigated their potential uses.

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Uploaded on July 8, 2023
Number of pages 17
Written in 2022/2023
Type Exam (elaborations)
Contains Questions & answers

ib biology
biology
ib biology ia
internal assessment
bio
biology experiment
ib

Institution Secondary school
IB Biology
School year 5

aliotuzoglu

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What is the effect of the concentration of nitrogen fertilizer applied to soil on
nitrogen use efficiency (NUE) for the top 5 contemporary fertilizer-consuming
countries?

1. EXPLORATION

1.1 Introduction
The population of the world has quadrupled during the last century and is set to increase in the
following decades, and the global food demand is expected to increase around 60-100% by
2050.1 This is expected to challenge the agriculture market with unprecedented high demands,
creating a need for increased productivity. Yet, the current growth of crop yields is insufficient to
meet this increased demand because factors such as climate change are deteriorating the
sustainability of agriculture.2 Therefore, the appropriate use of fertilizer to deal with increased
needs for productivity in agriculture is a significant issue. As a result of increasingly unstable
climatic conditions, erosion is increasingly apparent, with “16% of soils [being] estimated to have
a lifespan of less than 100 years,”3 concerning many about the fast pace of the thinning of soil.
The use of nitrogen fertilizers is a widespread agricultural method to generate more yields per
unit area from the arable soils that remain unharmed from such environmental disturbances4.

The effectiveness of nitrogen fertilizer in repleting the nutrient content of soil is caused by how
plants use nitrogen heavily for growth and development5. However, although making up
approximately 80% of atmospheric gases, nitrogen cannot be used by plants in its natural gas
form6. Instead, plants usually use nitrogen naturally in the form of ammonium created by an

1 (Elferink and Schierhorn)
2 Ibid
3 (“Do We Only Have 60 Harvests Left?”)
4 (Elferink and Schierhorn)
5 (Leghari et al.)
6 Ibid
1

,organic process of nitrogen fixation, where “nitrogen-fixing bacteria convert atmospheric nitrogen
to ammonia”7. “Once in this form, it can be absorbed by plants and then […] enter food chains” 8.
But natural fixation processes are unable to meet current food demands since, because of the
overproduction of crops, they are depleted over time 9. Soils depleted of organically fixated
nitrogen are replenished in modern agriculture by nitrogen fertilizers, which use nitrogen fixated
industrially through the Haber-Bosch process, where “nitrogen and hydrogen gases pass through
an apparatus at a controlled temperature, pressure, and flow rate, and in the presence of a
catalyst, ammonia is formed in an energy-efficient process.”10 As a result of this process, billions
are fed by crops produced using nitrogen fertilizer11.

In this investigation, the current efficiency of the use of nitrogen fertilizer is examined through the
research question “What is the effect of the concentration of nitrogen fertilizer applied to soil on
nitrogen use efficiency (NUE) for the top 5 contemporary fertilizer-consuming countries?”. Here,
NUE is a measure for the amount of nitrogen fertilizer that is effectively absorbed by growing
crops. NUE is the “dry mass productivity per unit N taken up from soil” 12 and is commonly referred
to in evaluating ways in which plants respond to different levels of nitrogen availability in soil. In
this research, as a parameter of NUE, the calculated percentage ratio between nitrogen input and
output from Our World in Data13, which gives statistical displays sources from a primary scientific
source14, will be used. Data for mass of nitrogen fertilizer used per hectare will be taken from the
Gapminder database15, which displays data from studies conducted by the United Nations Food

7 (Allot and Mindorff 649)
8 Ibid
9 Ibid
10 (“Fritz Haber”)
11 (McKie)
12 (Nitrogen Use Efficiency Revisited | SpringerLink)
13
(“Nitrogen Fertilizer Use per Hectare of Cropland”)
14
(Lassaletta et al.)
15 (Gapminder Tools)
2

, and Agriculture Organization, and
Figure 1: Top 5 Nitrogen-Fertilizer Consuming
is thus a reliable source to gather Countries
information. To investigate
whether an increase in the mass of
nitrogen fertilizer per hectare
correlates with increased NUE, a
chi-squared test between the two
variables will be conducted using
data on the world’s top five
nitrogen fertilizer consuming
countries, as shown in Figure 1.

1.2 Research question (RQ)
What is the effect of the concentration of nitrogen fertilizer applied 16 to soil on nitrogen use
efficiency17 (NUE) for the top 5 contemporary fertilizer-consuming countries?

1.3 Background to My Choice of RQ
Both of my parents are landscape architects and own a company that sells plants, fertilizer and
other organic materials used in construction. Hence, the efficiency of agriculture, the maltreatment
of soil and the over-use of fertilizer are topics topic of frequent discussion at home. Therefore, I
have been acquainted to and interested in sustainability, ecological dynamics, and agriculture
since a young age. As a result of this interest, I am subscribed to newsletters and magazines
about ecology which inform me of current developments in these fields. While doing general
research about agriculture, I came across a chart about fertilizer use on the website Our World in
Data. After a closer look, I decided that it would be a great fit to use for statistical analysis for an
investigation on the efficiency of nitrogen fertilizer concentration.

16 in kg of nitrogen fertilizer applied per hectare of arable land
17 ratio of nitrogen output and nitrogen input
3

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