R3102

THE ROOT ENVIRONMENT, PLANT NUTRITION & GROWING SYSTEMS

Level 3

Wednesday 26 June 2019

13:30 – 15:10

Written Examination

Candidate Number:……………………………………………………………… Candidate Name:………………………………………………………………… Centre Number/Name:…………………………………………………………...

IMPORTANT – Please read carefully before commencing:

i) The duration of this paper is 100 minutes;

ii) ALL questions should be attempted;

iii) EACH question carries 10 marks;

iv) Write your answers legibly in the spaces provided. It is NOT necessary that all lined space is used in answering the questions;

v) Use METRIC measurements only;

vi) Use black or blue ink only. Pencil may be used for drawing purposes only;

vii) Where plant names are required, they should include genus, species and

where appropriate, cultivar;

viii) Where a question requires a specific number of answers; only the first answers given that meet the question requirement will be accepted, regardless of the number of answers offered;

ix) Please note, when the word ‘distinct’ is used within a question, it means

that the items have different characteristics or features.

Ofqual Unit Code M/505/2839 Please turn over/…..

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Q1

Describe how low organic matter content of a soil can influence the following:

i) moisture holding capacity; ii) soil temperature; iii) nutrient holding capacity.

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Q2 a)

b)

Describe TWO differences between sedentary and non-sedentary (transported) soils. ………………………………………………………………………………………...

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Describe the formation of TWO NAMED non-sedentary soils

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Q3

State how the following requirements of growing media influence the choice of constituents using a distinct NAMED example for EACH.

i) stability; ii) sterility; iii) pH; iv) water holding capacity; v) nutrient content.

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Q4 a)

b)

State ONE horticultural situation in which an ebb and flow irrigation system may be used giving a NAMED crop example.

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Describe an ebb and flow system under EACH of the following headings:

i) TWO distinct advantages; ii) TWO distinct disadvantages.

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Q5 a)

b)

Describe TWO distinct NAMED soil structures. ………………………………………………………………………………………...

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………………………………………………………………………………………... Describe the effects on plant growth for EACH of the TWO soil structures named in a).

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Q6 a)

b)

Describe ONE role of nitrogen within plant metabolism.

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Describe the effects of FOUR NAMED soil bacteria on nitrogen availability.

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Q7

Describe the advantages to the horticulturist of EACH of the following types of fertiliser:

i) granules; ii) powders; iii) prills.

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Q8 a)

b)

State TWO symptoms of iron deficiency in plants. ………………………………………………………………………………………...

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Explain TWO possible causes of iron deficiency in plants.

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c)

Describe TWO ways by which horticulturists can rectify iron deficiencies. ……………………………………………………………………………………….....

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Q9 a)

Describe the management of an organic crop under EACH of the following headings:

i) weed control; ii) pest and disease management.

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Q10

Identify FOUR advantages and ONE limitation of the following techniques of soil cultivation:

i) double digging system; ii) no-dig system.

Double digging system No-dig system

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R3102

THE ROOT ENVIRONMENT, PLANT NUTRITION & GROWING SYSTEMS

Level 3

Wednesday 26 June 2019

Candidates Registered 98 Total Candidates Passed 55 83% Candidates Entered 66 67% Passed with Commendation 23 35% Candidates Absent/Withdrawn 30 31% Passed 32 48% Candidates Deferred 2 2% Failed 11 17%

General comments

The majority of candidates attempted and completed all the questions.

A wide range of marks was achieved by candidates taking this paper with some excellent papers and some really poor ones.

Where named plant examples are asked for, full botanical names were required to achieve full marks: genus, species and where appropriate variety, cultivar etc. needed to be written and spelt correctly. Where genus alone was given, all species in that genus need to show the characteristic asked for to gain any credit. Common names were NOT accepted and misspellings were penalised. Candidates needed to use unambiguous plant examples from sources such as the RHS Plant Finder and/or the RHS A-Z Encyclopaedia of Plants together with examples given in the syllabus and avoid obscure or difficult to verify plant examples were not credited.

Labels on diagrams needed to be carefully and correctly positioned to avoid ambiguity, not left hanging in mid-air. The labels need to touch the appropriate part of the diagram to be credited. Annotations on diagrams were accepted as an alternative to description in the text as long as these were clear and answered the question. No marks were awarded for artistic merit or for unlabelled diagrams.

Where a number of answers were specified in the question, e.g. ‘List TWO plant names’ or ‘Describe TWO functions’ only the FIRST TWO

answers given by a candidate were marked

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Q1

Q1

Describe how low organic matter content of a soil can influence the following:

i) moisture holding capacity; ii) soil temperature; iii) nutrient holding capacity.

Candidates were asked to describe how low organic matter content affected moisture holding capacity, soil temperature and nutrient holding capacity.

Candidates who related their answers to ‘low’ organic matter scored high marks, however candidates who explained the benefits of high organic matter levels, or who simply discussed the role of organic matter within the soil scored lower marks.

i) Low organic matter in the soil leads to reduced moisture holding capacity because soil organic matter itself will hold moisture in the soil. High scoring answers also included reference to low organic matter reducing aggregation and so reducing mesopores with a subsequent reduction in water holding capacity.

ii) The low organic matter content of the soil, with lower water content will lead to a more rapid change in temperature with soils warming faster in the spring and cooling more quickly in the autumn.

High scoring answers stated that a reduction in organic matter leads to a lighter coloured soil which results in reduced solar gain.

It should be noted that a significant proportion of candidates explained that low organic matter leads to a reduced level of soil microbes, which in turn result in a cooler soil. While the presence of soil microbes within a compost heap influences temperature, this increase in temperature would be insignificant in the soil, to the extent the difference could not be measured.

iii) In general, low organic matter content of the soil reduces nutrient holding capacity through reduced levels of colloidal humus and thus reduced cation exchange sites, reducing nutrient availability and allowing increased leaching of nutrients.

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26

Q2

Q2

a)

b)

a)

b)

Describe TWO differences between sedentary and non-sedentary (transported) soils. Describe the formation of TWO NAMED non-sedentary soils

Candidates were asked to differentiate sedentary and non-sedentary soils. Correct answers stated that sedentary soils are formed in situ over parent rock whilst non-sedentary rocks are formed through transportive means such as wind/water and will differ from the local bedrock. Transported soils are often more fertile than non-transported soils as they may contain minerals from a variety of transported parent materials.

Candidates were asked to describe the formation of two named non-

sedentary soils

Candidates whose answers included named examples such as loess or alluvial soil, together with a description of how these soils are formed, from the weathering of the parent rock, through to transport by wind for loess and water for alluvial soils and subsequent deposition, scored high marks.

Some candidates related their answers to other soil types; for example, “brown soil” and “podzol” and “gley” were commonly named. As the latter two are sedentary soils no marks could be awarded.

MARKS 4

6

27

Q4

Q4

a)

b)

a)

b)

State ONE horticultural situation in which an ebb and flow irrigation system may be used giving a NAMED crop example. Describe an ebb and flow system under EACH of the following headings:

iii) TWO distinct advantages; iv) TWO distinct disadvantages.

Candidates were asked to state one horticultural situation in which an ebb and flow irrigation system might be used. A named crop example was also requested.

Candidates who stated glasshouse, polytunnel or growing rooms as the horticultural situation and who named pot plants, micro-herbs, or hardy nursery stock in their answers gained full marks.

Some candidates stated the cultivation of tomatoes, as ebb and flow kits are available for this purpose on the amateur gardening market, this answer was also accepted.

i) Candidates were asked to describe two distinct advantages of an ebb and flow system. Correct answers included the even watering of plants, sustainable aspects through the recirculation of water etc., a high degree of control of fertigation, lack of moisture on the crop canopy reducing fungal pathogen outbreaks along with the wet-dry cycle flushing air into and out of the growing medium.

ii) Candidates were asked to describe two distinct disadvantages of an ebb and flow system. Correct answers included the risks of pathogen build up from the recirculation of water, in particular Pythium/Phytophthora and Rhizoctonia. The build-up of fertiliser salts at the base of the root zone, high start-up costs relating to the purchase of injectors and monitoring equipment, along with the costs associated with bench maintenance all led to high marks being awarded, especially when the answer included a developed response as part of the description. For example, a mark would be awarded for citing root borne pathogens as a disadvantage, with the named example gaining a further mark.

MARKS 2

4

4

28

Q5

Q5

a)

b)

a)

b)

Describe TWO distinct NAMED soil structures. Describe the effects on plant growth for EACH of the TWO soil structures named in a).

An example and description of a named soil structure was required,

Commonly named structures included Crumb, Granular, Aggregated, Prismatic, Columnar, Platy and Blocky.

Descriptions such as the presence of horizontal layers in a soil with platy structure, or the lack of observable aggregates in a massive soil structure gained candidates full marks.

Candidates in this part of the question were asked to describe the effects on plant growth for each of the two structures named in part a) of the question.

This part of the question required candidates to apply their knowledge of soil structure in relation to plant growth.

Strong candidate answers included, for example, a platy soil structure with horizontal units being impermeable to roots and water, thereby causing a reduction in plant growth. Platy structures could also promote waterlogging of the soil leading to anaerobic respiration by the plant roots and poor plant growth.

A soil with a columnar structure has dense aggregates which restrict root growth to the cracks between them restricting water uptake and nutrient foraging and so restricting growth.

MARKS 4

6

29

Q6

Q6

a)

b)

a)

b)

Describe ONE role of nitrogen within plant metabolism.

Describe the effects of FOUR NAMED soil bacteria on nitrogen

availability.

Candidates were asked to describe one role of nitrogen within plant

metabolism.

Correct candidate answers included, for example, nitrogen being part of the chlorophyll molecule, which is required for photosynthesis or that nitrogen is a component of amino acids which are building block for proteins.

In this part of the question candidates were required to describe the

effect of four named soil bacteria on nitrogen availability.

Candidates who correctly named four soil bacteria, and who stated their individual role correctly scored full marks. Good answers commonly included the examples of Nitrosomonas, Nitrobacter, Rhizobium, and Azotobacter together with the correct process of fixing or denitrifying nitrogen compounds.

For example, Nitrobacter oxidises nitrites to nitrates and increases nitrate availability to plants.

However, candidates who stated that there are nitrifying bacteria and denitrifying bacteria, without naming specific bacteria, gained fewer marks, and those who named fungi and described their role gained no marks.

MARKS 2

8

30

Q7

Q7

Describe the advantages to the horticulturist of EACH of the following types of fertiliser:

iv) granules; v) powders; vi) prills.

Candidates were asked to describe the advantages to the horticulturist of granules, powders and prills used as fertilisers in horticulture. High scoring answers described the advantages of each of the specific types of fertiliser.

i) Correct answers included granules being relatively uniform, which have the advantage to the horticulturist of accurate application. Other correct answers related to the ease of weighing granules and the reduced risk provided by granules to the operator. Some candidates gave the advantages to the horticulturist of using controlled release fertilisers as granules. These answers were accepted, but could not be repeated to gain marks under part iii) for prills.

ii) Candidates’ answers related to powders often included the

enhanced solubility of powders, along with their ‘fast’ action. Candidates also stated correctly that greater control of nutrient dosage can also be achieved with powders and compared to some slow release formulations, which deliver in response to temperature. Other advantages included their use in liquid feed and fertigation systems, along with foliar feeds.

iii) Candidates’ answers relating to prills described the

advantages of using a fertiliser which is more uniform in size and shape compared to granules with a greater degree of precision in application and spreading being achieved. Some candidates related their answers to controlled release fertilisers which are resin bound thus forming a prill. Some candidates however incorrectly stated that controlled release fertilisers are bound with clay rather than resin.

MARKS

3 3 4

31

Q8

Q8.

a)

b)

c)

a)

b)

State TWO symptoms of iron deficiency in plants. Explain TWO possible causes of iron deficiency in plants.

Describe TWO ways by which horticulturists can rectify iron deficiencies

Candidates were asked to state two deficiency symptoms of the micronutrient iron in plants.

Correct responses included interveinal chlorosis, which as iron is not mobile in plants affects the younger foliage. Candidates were expected to use terms such as interveinal chlorosis along with the location of such foliage to gain two marks. Candidates stating a more generic symptom, “look yellow”, gained fewer marks.

Candidates were asked to explain two possible causes of iron

deficiency in plants.

Correct answers included that iron is unavailable to plants in soils and growing media with high pH, or that iron could be in the wrong form, for example being present as Fe3+ ferric ion rather than Fe2+ ferrous ion, which is the usual form that dicotyledonous plants take up iron. Mention of antagonistic effects of other cations was also a correct response and gained high marks.

In this part of the question candidates were asked to describe two ways

that horticulturists can use to rectify iron deficiencies.

Correct answers included the use of chelates such as ETDA as well as iron sulphate and adjustments of pH. To gain full marks the answer had to describe how the iron deficiency would be rectified, and so while adjusting pH is correct, the examiners were looking for a fuller description of how this is achieved, for example through the use of powdered sulphur to reduce pH.

MARKS 2

4

4

32

Q9

Q9

a)

Describe the management of an organic crop under EACH of the following headings:

i) weed control; ii) pest and disease management.

This question required candidates to describe the management of an organic crop, considering weed control and then pest and disease management techniques.

All answers given had to abide to the requirements of an organic certification body.

i) In the case of weed control, use of examples such as flame weeding, the use of membranes and mulches along with mechanical control were awarded high marks. As the question asked candidates to describe the control, candidates were awarded marks for the use of mulch as a method of weed control, with full marks being awarded when the material was named, along with the depth of material, or a discussion relating to their use on annual rather than perennial weed.

ii) In the case of pest and disease management, candidates gaining high marks described a range of appropriate measures in detail. The use of crop rotations to reduce the build-up of soil born pests and diseases, the use of biological control with correctly named examples of biological control agents along with their targets, the use of resistant cultivars, the use of nesting boxes to encourage specific insectivorous birds, methods of ensuring high standards of hygiene and specific cultural practices all gained high marks.

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33

Q10

Q10.

Identify FOUR advantages and ONE limitation of the following techniques of soil cultivation:

i) double digging system; ii) no-dig system.

Double digging system No-dig system

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nta

ge

s 1. 1.

2. 2.

3. 3.

4. 4.

Lim

it

ati

on

1. 1.

This question continued the theme of organic growing, with specific reference to the advantages and disadvantages of “no dig” gardening when compared to double digging.

For double digging correct responses included the opportunity to incorporate organic matter and thereby improve soil structure. In addition, the breaking up of soil pans as well as bringing soil pests to the surface were common responses.

In contrast, a ‘no-dig’ strategy included the advantages of preservation of soil structure and limited opportunity of bringing weed seeds to the surface. Responses also included preservation of natural soil organisms including flora and fauna.

Limitations of double digging generally included aspects of labour intensity, whilst limitations of ‘no-dig’ systems included difficulty in controlling perennial weeds and also, they require a considerable quantity of organic material to be applied annually which may be unrealistic in some situations.

2

2

2

2

2

34

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They must not be reproduced or sold.

The Royal Horticultural Society, Wisley, Woking, Surrey GU23 6QB. Charity Registration Number: 222879/SC038262