NATIONAL QUALIFICATIONS CURRICULUM SUPPORT
Chemistry
Agrochemicals
Advice and Guidance
for Practitioners
[NATIONAL 5]
This advice and guidance has been produced to support the profession with the delivery of
courses which are either new or which have aspects of significant change within the new
national qualifications (NQ) framework.
The advice and guidance provides suggestions on approaches to learning and teaching.
Practitioners are encouraged to draw on the materials for their own part of their continuing
professional development in introducing new national qualifications in ways that match the
needs of learners.
Practitioners should also refer to the course and unit specifications and support notes which
have been issued by the Scottish Qualifications Authority.
http://www.sqa.org.uk/sqa/34714.html
Acknowledgement
© Crown copyright 2012. You may re-use this information (excluding logos) free of charge in
any format or medium, under the terms of the Open Government Licence. To view this licence,
visit http://www.nationalarchives.gov.uk/doc/open-government-licence/ or e-mail:
psi@nationalarchives.gsi.gov.uk.
Where we have identified any third party copyright information you will need to obtain
permission from the copyright holders concerned.
Any enquiries regarding this document/publication should be sent to us at
enquiries@educationscotland.gov.uk.
This document is also available from our website at www.educationscotland.gov.uk.
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Contents
Introduction
4
Curriculum for Excellence
5
Concept development
6
Approaches to learning and teaching, and skills for learning, life
and work
10
The importance of agrochemicals for Scotland
14
The importance of agrochemicals for the world
15
History of agrochemicals
17
Food security
20
Alternatives to the use of agrochemicals
22
Sustainability and farming for a better environmental climate
24
Pollution, chemical tests and water
27
General resources
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Introduction
This document provides advice and guidance on the topic of agrochemicals
within National 5 Chemistry. It is intended for use by practitioners and is
non-mandatory. It is anticipated that practitioners will be creative and
innovative in planning approaches to meet the needs of learners. The advice
and guidance should be used in a reflective and selective manner.
The teaching and learning suggestions are set within the Scottish context and
also provide links to global implications. Fertilisers are the focus for this
guide, but the importance of pesticides, herbicides and fungicides should not
be forgotten and may provide valuable learning experiences for individual
learners.
The teaching ideas and learner activities are varied and it is not intended that
all learners should experience all activities. Professional judgement and
knowledge of the interests and needs of individual learners will ena ble
practitioners to select appropriately from the suggested ideas.
Reflective questions are provided to aid practitioners in planning learning and
teaching to meet the needs of learners. These questions are intended for
practitioners’ use in the identification of big issues that underpin the learning
and teaching for this context. Additionally, these questions can be used as
starter activities to promote thinking, as questions for a ‘rich’ homework task,
as a basis for discussions or as personal/group research questions. Debate
could be introduced throughout many aspects of this unit.
It is worthwhile reiterating the importance of practical investigations in
Chemistry. This guide does not strive to provide experimental guidelines , but
rather a context for the chemistry and where it fits into the everyday lives of
learners.
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Curriculum for Excellence
The aim of Curriculum for Excellence
is to ensure all learners develop the
skills, knowledge and confidence that
they require to be successful in today’s
fast-changing society. It promotes a
holistic approach to education where
learners develop the skills and can
become successful learners, confident
individuals, responsible citizens and
effective contributors. Building the
Curriculum 3 provides a framework for
learning and teaching and the purpose
of the curriculum.
As described in Curriculum for Excellence learners should experience a
variety of enriching educational experiences that encompass , among other
things, active learning, co-operative learning and independent learning,
including personal research, dialogue with peers and educators , and the use of
ICT. Learners should be fully involved in their learning and be given
opportunities for personal achievement in order to help build motivation,
resilience and confidence. Interdisciplinary learning is also important to
allow links to be made across subject areas and to develop learners’ higherorder thinking skills. Agrochemicals can be linked to biology, social sciences ,
and health and wellbeing. Global citizenship can be developed to promote
understanding of the interdependence between people, the environment and
the impact of actions locally as well as globally.
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Concept development
The progression for agrochemicals and chemical tests from Curriculum for
Excellence level 2 to level 4 Science and then to National 5 Chemistry is as
shown below. There are also clear links to National 4/5 Biology (Food
security) and Science. Topical science can also be linked to this area of
chemistry. Practitioners should also refer to the Concept Development in the
Sciences paper, which provides more depth to each line of development.
These comments are provided in italics.
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Agrochemicals
I have collaborated in the design of an investigation into the effects of
fertilisers on the growth of plants. I can express an informed view of the risks
and benefits of their use.
SCN 2-03a
Learners can explore the role of fertilisers through pra ctical activities
involving, for example, house plant nutrient fertilisers. The effect of factors
such as dilution of the fertiliser or use of different fertilisers can be
investigated.
Through investigations and based on experimental evidence, I can explain the
use of different types of chemicals in agriculture and their alternatives , and
can evaluate their potential impact on the world ’s food production.
SCN 3-03a
Learners grow plants using a variety of growth promoters and inhibitors to
investigate ways in which plant growth can be altered. Learners could
undertake research into the use of these and of alternatives, including the
growth of genetically modified (GM) plants. They can explore the role of
pesticides, herbicides and fungicides. They coul d consider organic farming
methods and compare these with the use of artificial chemicals and GM
crops, enabling learners to develop informed views on the use of each.
Through investigating the nitrogen cycle and evaluating results from practical
experiments, I can suggest a design for a fertiliser, taking account of its
environmental impact.
SCN 4-03a
Learners design an artificial fertiliser taking account of the major nutrients
that are required by a plant for healthy growth , ie nitrogen, phosphorus and
potassium in appropriate proportions. They can consider the solubility of
salts containing the major nutrients and potential problems associated with
their overuse. There are useful opportunities to develop numeracy skills, for
example in the calculation of percentage compositions of simple fertilisers.
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Chemical tests
I have investigated different water samples from the environment and
explored methods that can be used to clean and conserve water , and I am
aware of the properties and uses of water.
SCN 2-18a
Learners explore common uses of water, for example as a solvent, coolant
and heat source. They can participate in practical activities to clean different
water samples, using a range of methods such as filtering, evaporating and
use of filter beds.
Having taken part in practical activities to compare the properties of acids
and bases, I have demonstrated ways of measuring and adjusting pH , and can
describe the significance of pH in everyday life.
SCN 3-18a
Learners compare the properties of common acids and bases (for example
acids have a sour taste; bases have a bitter taste and slippery feel; strong
acids and bases are corrosive; both acids and bases dissolve in water and
react with indicators to produce different colour changes; acids and bases
neutralise each other). Knowledge of the formation and naming of simple
salts underpins this outcome. The implication of situations in which pH levels
cannot be returned to normal levels can be discussed. Learners have
opportunities to further develop the use of both word and formula equations
based on their developing knowledge of chemical formulae.
I can monitor the environment by collecting and analysing samples. I can
interpret the results to inform others about levels of pollution and exp ress a
considered opinion on how science can help to protect our environment.
SCN 4-18a
Learners can collect and analyse samples collected from the environment (eg
soil, air or water samples). They can use the results of analysis to present
findings about the levels of pollution in the environment and present informed
views about causes and effects. The use of data from a variety of sources can
be incorporated into the learner’s experience.
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Topical science
I have researched new developments in science an d can explain how their
current or future applications might impact on modern life.
SCN 4-20a
Having selected scientific themes of topical interest, I can critically analyse
the issues and use relevant information to develop an informed argument.
SCN 4-20b
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Approaches to learning and teaching, and skills for
learning, life and work
Learners should experience a range of approaches that are designed to
develop knowledge, understanding and the skills required for learning, life
and work. These should be experiential and learner led. An investigatory
approach is encouraged in Chemistry and a holistic approach should be
adopted to encourage simultaneous development of learners’ conceptual
understanding and skills. The study of agrochemicals provides learner s with
opportunities to develop their competencies in practical skills, problem
solving, critical thinking and working collaboratively. Additional information
is provided in the Course and Unit Support Notes.
Building the Curriculum 4 details the skills for learning, life and work and
how they are embedded in the experiences and outcomes and the senior
phase.
The agriculture and agrochemicals industries provide a wide spectrum of
employment possibilities, from council gardeners to PhD chemists, and
therefore the study of the topic can provide links to many different walks of
life. Partnerships with local agrochemical companies and environmental
agencies could be made to further support learning in this area. STEM
ambassadors are a useful resource for this and other science topics.
The Course and Unit Support Notes for National 5 Chemistry suggest skills
and techniques that are important in the development of young scientists in
preparation for the world of work.
The study of agrochemicals would allow opportunities for learners to
practise:






titrations
safe methods of heating
salt preparation
drawing diagrams of apparatus
using tables to represent data
representing experimental data using bar or line graph s and sketching lines
or curves of best fit if appropriate
 suggesting improvements to investigations with reasoning .
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The following areas of Responsibility of All have particular relevance to the
study of Agrochemicals.
Numeracy
A numerate person will have acquired and developed fundamental skills and
be able to carry out number processes but, beyond this, being numerate also
allows us to access and interpret information, identify po ssibilities, weigh up
different options and decide on which option is most appropriate (Numeracy
Principles and Practice Paper).
Numeracy is the ability to use numbers in order to solve problems by
counting, doing calculations, measuring and understanding graphs and charts.
It is also the ability to understand the results. Learners will have
opportunities to extract, process and interpret infor mation presented in
various formats, including tabular and graphical. Practical work will provide
opportunities to develop measurement skills.
Number processes
Number processes means solving problems arising in everyday life. Learners
have the opportunity to develop numeracy skills by carrying out and
understanding calculations when working out formulae, balanced equations
and percentages in composition of fertilisers problems. Learners should deal
with data and results from experiments/investigations an d everyday class
work, making informed decisions based on the results of these calculations
and understanding the results.
Information handling
Learners will experience information handling opportunities when dealing
with data in tables, charts and other graphical displays to draw sensible
conclusions throughout the course. This involves interpreting the data and
considering its reliability in making reasoned deductions and informed
decisions.
Literacy
The literacy experiences and outcomes promote the development of critical
and creative thinking as well as competence in listening , talking, reading,
writing and the personal, interpersonal and team-working skills that are so
important in life and in the world of work (Literacy Principles and Practice
Paper).
Learners develop the skills to effectively communicate key chemical concepts
and to clearly describe chemical issues in various media f orms. Learners will
have opportunities to communicate knowledge and understanding with an
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emphasis on applications and environmental/social impacts. Learners will
have opportunities to develop listening and reading skills when gathering and
processing information.
In addition, learners will have opportunities to develop other skills as detailed
below.
Applying
Learners should be given opportunities to plan experiments throughout the
course and to use existing information to solve problems in different
contexts.
Analysing and evaluating
During practical work, learners should be given the opportunity to identify
and review the experimental procedure and to identify improvements.
Learners will use their judgement when drawing conclusions from
experiments.
When researching topics, learners should identify and weigh up the features
of a situation or issue in chemistry and use their judgement in coming to a
conclusion. This includes reviewing and considering any potential solutions
with justifications.
Working with others
Learning activities provide many opportunities in all areas of the course for
learners to work with others. Practical activities and investigations offer
opportunities for group work, which is an important aspect of science and
should be encouraged.
Creating
Learners can demonstrate creativity through learning in chemistry. In
particular, when planning and designing experiments/investigations learners
have the opportunity to be innovative in their approach. They also have
opportunities to make, write, say or do something new.
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Citizenship
This course has the potential to provide learners with an extensive range of
practical activities that provide many opportunities for them to work cooperatively with others. Learners will develop citizenship skills when
considering the applications of chemistry in our lives and environmental
and/or ethical implications.
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The importance of agrochemicals for Scotland
Many of Scotland’s industries, including life sciences, electronics,
chemicals, food and drink, and energy, have the chemical sciences at their
core. These industries are dependent on innovative chemistry to create new
products and new market opportunities, and they could not exist without this
underpinning science. Chemistry’s contribution to Scotland’s economic
past, present and future is immense.
The chemicals industry is one of Scotland’s biggest export earners,
responsible for approximately 12% of manufacturing exports. It is also one of
our highest value industries, providing employment for almost 14,000 people
directly and nearly 70,000 in total through dependent s ervices. Scotland’s
contribution to the UK industry is slightly ahead of its population ratio,
amounting to almost 10% of UK output.
Globally, the chemicals industry has been growing at an average of 3.3% per
annum from 2002 to 2012.
Given the economic importance of this industry, there are many strategies to
ensure continued investment in it and the employment potential for young
people is promising.
The chemical industries are diverse and cover a wide range of products ,
including basic chemicals, plastics, pharmaceuticals, fertilisers, pesticides
and fungicides, pigments, food ingredients, textil e printing chemicals, inkjet
dyes and vitamins. These can be divided into three categories: basic
chemicals, specialty chemicals and pharmaceutical/fine chemicals.
Agrochemicals are classed as fine chemicals and make an important
contribution to the chemicals industry in Scotland.
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The importance of agrochemicals for the world
The current population of Scotland is approximately 5.2 million. In January
2008, General Register Office of Statistics figures predicted that Scotland’s
population would rise to 5.54 million by 2033. Trends in population statistics
indicate that there is a decrease in both birth rates and death rates.
Current global projections show a continued increase in population (but a
steady decline in the population growth rate), with the global population
expected to reach between 7.5 and 10.5 billion by 2050.
A starting point for this learning might be to encourage learners to examine
their prior learning around a number of questions :
 What effect will an increasing population have on the world’s resources?
 In what ways do you think governments can have an effect on population
growth?
 What reasons can you suggest for the falling birth rate in Scotland?
 What reasons can you suggest for the falling death rates in Scotland?
 What implications could the falling rates have on society?
 If the population continues to increase, do you think there will be enough
food for everyone? Explain your reasons for your answer and suggest
possible solutions to ensure that there will be enough food.
As the global population increases it will continue to be necessary to invest in
efficient methods for optimising agriculture globally. The number of people
without enough food to eat on a regular basis remains stubbornly high, at
over 900 million in 2010, and is not falling significantly. Over 85% of the
world’s undernourished people live in developing countries.
The current global population is estimated to be around 7 billion. It is
expected to rise to between 7.5 and 10.5 million by 2050. Agrochemicals may
be used as part of the global solution to maximise the production of food.
There is scope for much debate in this topic.
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Reflective questions for learners
 Can the use of agrochemicals ensure that there is enough food for all
nations?
 Consider the nutrients in food. Where will these nutrients come from?
Where will these nutrients go to?
(This may allow for the idea of a learner-generated nitrogen cycle or
nutrient cycle to be developed.)
 Can you suggest solutions to help undernourished people?
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History of agrochemicals
While considering the importance of agrochemicals learners may have
researched and discussed some of the reasons for using agrochemicals.
Practitioners could allow learners to research the history of fertilisers to
encourage thinking about chemical processes.
Reflective questions for learners
 It has been claimed that fertilisers can help to feed the global population.
Are fertilisers a new development of the 21 st century or have they been
used in the past?
Historians have documented the use of fertiliser in ancient times.
Egyptologists point out that fertilisers were used regularly in both agriculture
and horticulture.
Use of commercial fertilisers has only a short history compared to the length
of time that humans have been known to grow crops. It is believed that crop
production began some 6000–10,000 years ago. It was not until the 1840s that
limited quantities of a few types of natural commercial fertiliser, such as
Peruvian guano and Chilean sodium nitrate, were first used in the Western
world.
Ammonia and Nitric Acid lie at the heart of the agrochemical world.
Ammonia is now made industrially by the Haber process named after Fritz
Haber. It was made for the first time in 1774 and by 1785 its exact
composition had been determined.
Nitric acid was synthesised for the first time in 800 AD but it was not until
1771 that it was being produced commercially. Commercial production of
nitric acid is via the Ostwald process after Wilhelm Ostwald. Urea was
identified in 1773 and in 1775 the presence of large amounts of calcium
phosphate in bones was confirmed.
Ammonia was able to be made industrially and on a large scale as a result of
the invention of the Haber process at the beginning of the 20th century. The
process allows the economical fixation of atmospheric nitrogen in the form of
ammonia, which in turn allows for the industrial synthesis of various
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explosives and nitrogen fertilisers, and is probably one of the most important
industrial process developed during the 20th century.
In 1909, German chemist Fritz Haber successfully fixed at mospheric nitrogen
in a laboratory. This success had extremely attractive military, industrial and
agricultural applications. In 1913, barely 5 years later, a research team from
BASF, led by Carl Bosch, developed the first industrial -scale application of
the Haber process, sometimes called the Haber –Bosch process.
The industrial production of nitrogen prolonged World War I by providing
Germany with the gunpowder and explosives necessary for the war effort
even though it no longer had access to nitrates from Chile. During the
interwar period, the lower cost of ammonia extraction from the virtually
inexhaustible atmospheric reservoir contributed to the development of
intensive agriculture and provided support for worldwide population growth.
Ammonia provides the feedstock for the Ostwald process, which is a chemical
process used to produce nitric acid. It was developed by Wilhelm Ostwald
and patented in 1902. It is a mainstay of the modern chemical industry.
Fertilisers are still misused in modern times. They are commonly used to
make ‘backyard’ bombs and were used in the failed bomb attacks on London
after the 7/7 attacks (BBC news).
Reflective questions for learners
 Haber has been described as the father of chemical warfare as a result of
his research on the uses of chlorine during W orld War I. He was awarded
the Nobel Prize in 1918, but several French scientists refused to accept
awards from the same stage as him. Scientific discoveries are sometimes
shrouded in controversy. To what extent do you think scientists use their
discoveries for positive ends?
 The Haber process is optimised at 500°C and a pressure of 200 atm. What
factors impact on the conditions that industrial processes operate at?
Which factors are compromised in this case?
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Learning activities
 Learners could research Haber and present a scientific poster (or other
suitable knowledge product). Practitioners should be clear on what skills
they are wishing to develop. Success criteria should be developed and
shared with the learners. Peer- and self-assessment could be used for
formative assessment.
 Learners could debate controversial uses of scientific discoveries.
Examples could include Gerhard Schrader (nerve gases), Sir Marcus
Laurence Edwin Oliphant (nuclear fusion, which led to the hydrogen
bomb), Edward Teller (hydrogen bomb) or J. Robert Oppenheimer (the
atomic bomb) (elistmania). Again success criteria and peer/self-assessment
will enable learners to develop specific skills.
 Learners could isolate Rhizobium bacteria from root nodules on agar. This
activity would provide a relevant link to the nitrogen cycle, which is
discussed in National 5 Biology.
 Learners could synthesise fertilisers and be aware of the different
techniques that are used for this, ie titration and precipitation reaction.
 Learners could gain an understanding of how science is used in an
industrial context and develop strategies for the profitable operation of
fertiliser manufacture. The use of energy and raw materials is related to
the chemistry involved in the conversion of raw materials to nitrate,
phosphate and potassium fertiliser by using resources from the national
STEM centre
(http://www.nationalstemcentre.org.uk/elibrary/science/resource/578/capta
ins-of-industry).
Possible resources
Royal Society of Chemistry Alchemy series: ammonia and nitric acid
manufacture. Contains facts, videos and worksheets.
Animation of the Haber process.
Demonstration of the catalytic oxidation of ammonia.
Glow videos (The Nitrogen Cycle, What Plants Need to Grow).
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Food security
From 1950 to 1984 the Green Revolution transformed agriculture around the
world and grain production increased by over 250%. The world population
has grown by about four billion since the beginning of the Green Revolution
and most believe that, without the Revolution, there would be greater famine
and malnutrition than the UN presently documents (approximately 850
million people suffering from chronic malnutrition in 2005). A family is food
secure if they do not live in hunger or fear of starvation.
Agrochemicals play an important role in the strive for global food security.
This topic is covered in depth at National 5 Biology and the Advice and
Guidelines for that topic are extensive. Food security exists when all people,
at all times, have physical, social and economic access to sufficient, safe and
nutritious food to meet their dietary needs and food preferences for an active
and healthy life (UN Food and Agricultural Organisation (FAO)).
The Chatham House Report ‘The Feeding of the Nine Billion: Global Food
Security for the 21st Century’ (January 2009) indicated seven fundamental
pressures which affect global food prices, food production and therefore food
security:







population
diet
energy
land
water
climate change
labour.
Reflective question for learners
 Compare and contrast the role of governments versus society in preventing
global food shortages. Who is responsible for ensuring that research and
development in this area takes place in an ethical manner?
This is a complex idea for learners to take on board. A discussion could be
facilitated and scaffolded by the use of statement or opinion cards. These
questions could also form the basis for structured discussion tasks, scientific
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literacy regarding reporting of scientific issues or ethical issues relating to
technological development and control of food production. It could also be
used as an opportunity to develop skills in reading for information or as an
introduction to exploring the science underpinning the development of
learners’ understanding of ethical issues such as the risks and benefits of
pesticide use and the relationship between pes ticides and individuals’ health.
More information is available in the Advice and Guidance for National 5
Biology, Food security.
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Alternatives to the use of agrochemicals
Genetic modification
Multinational companies such as Monsanto are major international players in
seed production. They have genetically engineered many seed varieties to be
drought and pest resistant, and to improve crop yields.
In addition, they modify crops to protect their position in the market.
Monsanto engineered a terminator gene into seeds. This means that the seed
becomes sterile after a single harvest. Farmers can no longer save seeds from
the harvest and re-plant them, but must return each year to buy more seed,
therefore protecting the investment of the multinational company.
Irradiated seeds
Food is irradiated by brief exposure to X -rays, gamma rays or an electron
beam. The process is intended to reduce or eliminate harmful bacteria, insects
and parasites, and it can also extend the life of some products. Seeds can be
irradiated in order to promote germination. The use of this technique is
limited and varies from country to country. The European Commission
provides information on legislation and the monitoring of these practises in
Europe.
Crop-protection chemicals
Up to 40% of agricultural productivity would be lost without the effective use
of crop-protection chemicals (Royal Society of Chemistry). Agriculture is
facing emerging and resistant strains of pests. The development of new crop protection strategies is essential. It is vital that they are safe, overcome
resistant pests and are environmentally benign.
Pesticides (categorised into fungicides, insecticides and herbicides) are a
class of substances that prevent, destroy or kill any pest to a particular crop.
They can be chemically or biologically based depending on the pest and
situation. Common pesticide families include organochlorines,
organophosphates and carbamates. Clearly they may have benefits for crop
production, but toxicity to humans and other animals is often a concern.
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DDT, which acts as a nerve poison, was the first pesticide to cause
widespread concern and was banned in 1973 in the USA.
Reflective questions for learners
 What issues for farmers would arise from the use of terminator genes ,
particularly in developing countries?
 What effect might GM crops with sterile seeds have on non -GM crops in
nearby regions?
 Can learners think about any particular countries where irradiated seeds
and food may be particularly useful to promote food security? What issues
might arise? How could the media affect the common consensus on this
issue?
 Debate whether widespread pesticide use still has a place in global
agriculture.
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Sustainability and farming for a better
environmental climate
Scotland’s farmers are ready to play their part in moving towards a low
carbon society and not only can the industry cut emissions bu t farming
businesses can save costs at the same time and earn new income .
Richard Lochhead, Scottish Government Cabinet Secretary for Rural Affairs
and the Environment, June 2010
In 2008 the Scottish Government published the Climate Change (Scotland)
Bill, which created a long-term framework that will:
 introduce a statutory target to reduce Scotland ’s greenhouse gas emissions
by 80% by 2050
 establish an interim target of 50% emissions reductions by 2030
 establish a framework of annual targets
 include emissions from international aviation and international shipping.
This framework will help build a sustainable future for Scotland (Scottish
Government). It will contribute to the country’s sustainable economic growth
by moving the public and private sectors towards a low carbon economy.
The Scottish Government intends to deliver reduction targets though a
voluntary approach in close co-operation with the agricultural industry. A
variety of measures resulting in greenhouse gas emission savings as well as
business benefits have been identified in research undertaken by the Scottish
Agricultural College (SAC). Measures include livestock productivity
measures, improved nitrogen fertiliser management, improved manure and
slurry management, anaerobic digestion development and protecting soil
carbon. To deliver these measures, the Government developed the Farming
for a Better Climate (FFBC) initiative together with SAC, in order to provide
better information and advice to land managers. FFBC concentrates on five
key action areas to help Scottish farmers reduce emissions, adapt to climate
change and improve their businesses:
 using energy and fuels efficiently
 developing renewable energy
 locking carbon into the soil and vegetation
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 optimising the application of fertiliser and manures
 optimising livestock management and storage of waste.
Most farmers and their advisers are very aware of their environmental
responsibilities and the need to minimise nitrogen losses but they also have
other reasons to fine-tune nitrogen inputs:
 over application wastes money and causes crop lodging
 under application means failure to achieve yield potential and quality
premiums
 regulators increasingly depend on farmers being able to justify their
nitrogen input decisions.
Improving the efficiency of nitrogen use will bring both economic and
environmental gains. Better nitrogen management means:
 applying just enough nitrogen to meet the crop requirement
 recognising the contribution of organic manures
 ensuring adequate potassium and phosphorous indices and soil pH for
optimum nitrogen response
 providing sufficient amounts of sulphur to maximise the utilisation of the
nitrogen applied.
Information on optimising the application of fertilisers and manures can be
found on the SAC website. There is also interesting information regarding the
economics of fertiliser use.
Reflective question for learners
 What role can traditional and sustainable organic farming techniques (eg
composting, crop rotation, crop diversification, soil conservation, rip
ploughing) play in food security and minimising climate change?
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Learning activities
 Case studies on FFBC provide discussion material for learners to use in
debates. They could be used to evaluate how different farms are addressing
climate change. Alternatively, the information within the case studies
could be used to produce public information leaflets/posters or as
background information.
 Learners could synthesise fertilisers by titration or precipitation. Solubility
and pH could also be considered.
 Percentage mass composition calculations could be incorporated within
this section.
 Fertilisers could be made and analysed for nutrients from everyday
substances such as seaweed, egg shells, coffee granules and ash from fires .
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Pollution, chemical tests and water
Reflective questions for learners
 The use of agrochemicals is known to increase crop yields, but many
people choose to buy only organic products. Wh y might consumers choose
to avoid contact with fertilisers?
 Are there problems associated with the use of fertilisers?
The UN FAO has stated that good agricultural practices are ‘practices that
address environmental, economic and social sustainability for on -farm
processes, and result in safe and quality food and non -food agricultural
products’.
Bad agricultural practices can have very harmful effects on the environment
and populations wherever they happen.
Reflective questions for learners
 Why might it be necessary to have an international agriculture
organisation?
 What could the role of such an organisation contribute to society?
 Should individuals who grow food for their own use be expected to adhere
to the framework set out by an international agency? How could this be
monitored?
Learning activities
Consideration of agricultural practices gives opportunity for debate with
learners.
Intensive grain monoculture is considered to be a bad agricultural pra ctice
because it uses huge quantities of chemicals and wastes water through
irrigation. It is often used for the production of crops for biofuels, which can
be used instead of fossil fuels. Should we stop intensive monocrop production
in this case? There are several websites that could be used to allow learners
to develop a considered debate or an information publication.
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Learners could research some areas of bad agricultural practices, consider
potential problems and provide possible solutions. Some examples are
provided below.
Excess use of nitrates
Excess use of nitrates increases the run-off of them into rivers and lochs. This
encourages an over-production of algae known as algal bloom. This in turn
causes eutrophication, which causes lakes and lochs to become lifeless. Blue
baby syndrome is an illness that begins when large amounts of nitrates in
water are ingested by an infant and converted to nitrite by the digestive
system. The nitrite then reacts with haemoglobin (the oxygen -carrying blood
protein) to form methaemoglobin, which cannot carry oxygen. If a large
enough amount of methaemoglobin is formed in the blood, body tissues may
be deprived of oxygen, causing the infant to develop a blue colouration of
their mucous membranes and possibly digestive and respiratory problems.
Organic fertilisers
The use of seabird faeces as a fertiliser on St Kilda is believed to be a cause
of neonatal tetanus and subsequent deaths in the 1700s. Learners could
research and consider the use of other natural fertilisers. Why did this have
such an effect? Could similar faecal matter fertilisers in use today cause the
same problems?
Pesticides
‘One in every three bites of food you eat comes from a plant, or depends on a
plant, that was pollinated by an insect, most likely a bee, ’ said Dennis van
Engelsdorp of Penn State University's College of Agricultural Sciences.
Bee populations have been decreasing at a rapid rate. One reaso n suggested
for this is the overuse of pesticides. Learners could research this idea and
consider the implications to society if bee populations are not increased.
Water
Scotland’s waters are protected by the legislative document The Protection of
Water Against Agricultural Nitrate Pollution (Scotland) R egulations 1996.
Nitrate vulnerable zones (NVZs) are identified as being areas where
groundwaters have nitrate concentrations of more than 50 mg/l nitrate or are
thought to be at risk of nitrate contaminat ion. Action programmes established
by the Scottish Government are in place to reduce and prevent further nitrate
contamination. NVZs are reviewed at least every 4 years.
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NVZs are monitored for nitrates according to the Nitrate Monitoring
Programme 2003 and are also analysed for the following determinants:
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pH
conductivity
alkalinity
total suspended solids
nitrate
nitrite
ammoniacal nitrogen
total oxidised nitrogen chloride
sodium
potassium
calcium
magnesium
iron
manganese
phosphate
sulphate.
Learning activity
Learners could collect samples of water from local sources and qualitively or
quantitatively test for the presence of some of these determinants. Using the
STEM ambassador scheme an environmental chemist could enrich the
learning suggested here.
In order to establish whether Scottish groundwaters are exceeding this limit,
the Scottish Environmental Protection Agency (SEPA) has developed a
national groundwater monitoring network.
In 2000, SEPA sampled 150 groundwater monitoring locations for the
purposes of the Nitrates (Scotland) Regulations 1996. Results from this
monitoring programme confirmed elevated nitrate levels (ie above 50 mg/l) at
a number of monitoring locations.
The addition of further sites in 2002 by the British Geological Survey and
SEPA extended the network to 218 groundwater monitoring locations. The
intention is to increase the monitoring in those areas identified by research
groups as being at risk of having elevated nitrate concentration in
groundwater.
Nitrate run-off often attracts media interest and so it may be worthwhile for
practitioners to search local news for current issues. One such media item,
published in December 2011, detailed the rising nitrate levels in the Thames .
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Reflective questions for learners
 There are many complex factors that affect farmers. In light of the current
economic recession and climate change, to what extent do you think the
Government should provide incentives for farmers to continue to manage
nitrogen efficiently? What would these incentives be?
Learner activities
 Analytical techniques for different ions.
 Flame tests (eg for potassium ions).
 Precipitation (eg for chloride ions). This can also be used to analyse
phosphate ion content.
These tests could be used to test for a variety of substances found in local
sources such as soils and streams. There is scope to test for a variety of
substances by considering pesticides, herbicides and fungicides.
A quantitative determination of nitrates that is designed for Advanced Higher
projects can be found on the SSERC website.
Qualitative method for determination of Nitrates
Add sodium hydroxide solution and aluminium powder to the solution
containing the nitrate ions.
The aluminium reduces the nitrate ion (NO 3 – ) to an ammonium ion (NH 4 + ).
The ammonium ion reacts with hydroxide to produce ammonia gas and water :
ammonium + hydroxide
ammonia + water
NH 4 + (aq) + OH – (aq)
NH 3 (g) + H 2 O(l)
Ammonia gas can be identified with damp pH paper.
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Investigation on the effect of nitrate concentrations on algal growth
Learners will compare nitrate concentrations and rate of algae growth.
Equipment required
Non-toxic blue-green algae
Liquid fertiliser
Beakers
De-ionised water
Syringes with filter tips
Nitrate test kits (can also be sourced as aquarium nitrate te st kits from pet
shops)
Procedure
 Create a class set of control group solutions by adding 250 ml of deionised
water to each of four 500-ml beakers. One beaker will have only water. To
the other beakers add separately 2.0 ml of Miracle Grow fertiliser in the
following concentrations: 25%, 50% and 75%.
 Create a class set of algal colonies by repeating step 1 then adding 5.0 ml
of blue-green algae culture to each beaker.
 Using the nitrate test kit, test the nitrate concentration of each of the eight
beakers and record the results in a data table. Use the filtering syringe to
extract the fertiliser solution.
 Repeat the nitrate test on each algae sample for five consecutive days,
recording the nitrate concentration each time. Include in your observations
the appearance of the contents of the beakers each day. Be sure to note any
major changes.
 Using MS Excel, prepare a graph of the data with days on the x-axis and
nitrate concentration on the y-axis. There should be four graphs with two
lines each: the control and its partner algae colony.
 Practitioners must ensure they perform appropriate risk assessments in
alignment with their local authority.
Resources
Glow Video: Pollution (Water)
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General resources
SSERC
SSERC provides an extensive support system for practitioners primarily
through its website. Resources for Curriculum for Excellence (agrochemicals
strand) can be accessed through this website using a SSERC member’s log-in.
All Scottish teachers can apply for a log-in to SSERC by following
instructions on the website.
Royal Society of Chemistry (RSC)
The RSC is an excellent resource for a wide range of different areas. They
provide outreach support, publications and general resources.
The RSC is committed to meeting current global challenges head on and has
identified where the chemical sciences can provide technological and
sustainable solutions, and are promoting action and awareness in these areas.
Agriculture is one such priority area and some information on the possible
impact the chemical sciences can make is found within the website.
GrowHow have produced a booklet called Food, Farming and Fertiliser,
which examines the role of fertilisers in the context of the critical global
issues of food security, climate change and environmental protection .
http://www.growhow.co.uk/content.output/275/275/About %20Fertiliser/Abou
t%20Fertiliser/Education.mspx
Why Farming Matters has some interesting resources, including an activity on
farming and its effect on climate change. This is primarily a resource for
geography and citizenship, and so would be an appropriate start point for
interdisciplinary learning. IDL
http://www.face-online.org.uk/why-farming-matters/why-farming-matterssecondary
http://www.hgca.com/content.template/9/0/Education/Education/Education.m
spx
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BBC learning clips
Problems of using chemical fertilisers
Duration: 01:34
A news report explaining the
environmental and health impacts of
using chemical fertilisers.
The properties and uses of nitrogen
Duration: 00:52
fertilisers, nitrogen, water, nitrates,
farming, food supply, chemistry,
bitesize
nitrogen, element, fertiliser, protein,
DNA, nitrate, chemistry, bitesize
An animated description of the
properties and uses of nitrogen.
Nitrogen-fixing leguminous plants
Duration: 01:02
The role of nitrogen-fixing
leguminous plants in soil
improvement is examined and crop
rotation is briefly discussed.
population, fertilisers, nutrients,
legumes, bacteria, nitrogen, soil,
chemistry, bitesize
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