INCLUDING EXAMINERS COMMENTS R310 THE ROOT ENVIRONMENT, PLANT NUTRITION & GROWING SYSTEMS Level 3 Wednesday 7 February 018 13:40 15:0 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) iii) iv) ALL questions should be attempted; EACH question carries 10 marks; 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) vii) viii) ix) Use black or blue ink only. Pencil may be used for drawing purposes only; Where plant names are required, they should include genus, species and where appropriate, cultivar; 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; 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/505/839 Please turn over/..
Q1 ANSWER ALL QUESTIONS State what is meant by EACH of the following terms: i) field capacity; ii) available water content. MARKS 1 1 Describe how the soil s water holding ability is affected by EACH of the following structures: i) crumb; ii) platy; iii) prismatic. 3 3.......... Please see over/..
Total Mark Please turn over/.. 3
Q Identify TWO of the main types of metamorphic rock found in the UK. State TWO characteristics of ONE of the rocks named in. MARKS Please see over/.. 4
. MARKS c) Explain how TWO distinct weathering agents aid the breakdown of the parent rock to form soil. 6 Total Mark Please turn over/.. 5
Q3 State what is meant by the term 'cultivation window'. Explain how TWO factors affect the cultivation window of soils. MARKS 8 Please see over/.. 6
Total Mark Please turn over/.. 7
Q4 Explain how TWO factors affect the cultivation window of soils. 4 8 Please see over/..
State SIX benefits to plants provided by the actions of soil bacteria. 6 Total Mark Please turn over/.. 9
Q5 State what is meant by cation exchange capacity. State what is meant by the term 'buffering capacity'. MARKS Please see over/.. 10
c) Describe the characteristics of a clay soil under EACH of the following headings: i) cation exchange capacity and nutrient availability; ii) buffering capacity and liming requirement. 4 Total Mark Please turn over/.. 11
Q6 Describe for EACH of the following nutrients: i) ONE role within the plant; ii) TWO causes of deficiency. By completing the table below. MARKS Nutrient Calcium Magnesium Role in plant 1 1 Causes of deficiency 1 1 Describe how to rectify the deficiencies of EACH of the nutrients named in. 4 Please see over/.. 1
...... Please turn over/.. Total Mark 13
Q7 Describe what is meant by the term 'rhizosphere'. Describe how the specific properties of the rhizosphere benefit plant growth.... Please see over/.. 8 14
...... Please turn over/.. Total Mark 15
Q8 State SIX stages in the carbon cycle where carbon accumulates in the soil.. 6 Please see over/.. 16
Explain the effects of cultivation on carbon storage in the soil. 4 Total Mark Please turn over/.. 17
Q9 State TWO economic benefits for growers achieving certified organic status....... Describe the limitations for growers of achieving certified organic status. MARKS 8 Please see over/.. 18
...... 19 MARKS Total Mark Please turn over/..
Q10 Describe FIVE methods for managing potato blight, which are available to organic growers. MARKS 10...... Please see over/.. 0
Total Mark ******* 1
These questions are the property of the Royal Horticultural Society. They must not be reproduced or sold. The Royal Horticultural Society, Wisley, Woking, Surrey GU3 6QB. Charity Registration Number: 879/SC0386
R310 THE ROOT ENVIRONMENT, PLANT NUTRITION & GROWING SYSTEMS Level 3 Wednesday 7 February 018 Candidates Registered 86 Total Candidates Passed 79% Candidates Entered 75 Passed with Commendation 3% Candidates Absent/Withdrawn 10 Passed 56% Candidates Deferred 1 Failed 0% Senior Examiner s Comments On the whole this paper was well answered with the majority of candidates attempting and completing all the questions. The following guidelines should be of help to future candidates. 1. Where named plant examples are asked for, full botanical names (genus and species) are required to achieve full marks. Common names will not be given a mark.. Use the command statements e.g. list or name (single words only), state (a few sentences), describe or explain (a fuller answer) together with the mark allocation, to judge the depth of the answer. Half marks are often allocated where the basic information given is correct but needs further qualification to gain the full mark. 3. Where a number of answers are specified in the question, the examiner will not select correct answers from a list e.g. if the question states State TWO plant names, only the first two names given will be marked. 4. Labels on diagrams should be correctly positioned to avoid ambiguity and diagrams should be clearly drawn and annotated. No marks will be awarded for artistic merit. 5. Candidates should use unambiguous plant examples as reference sources from, for example, the RHS Find a Plant Service available on the RHS Website. 3
ANSWER ALL QUESTIONS MARKS Q1 State what is meant by EACH of the following terms: i) field capacity; ii) available water content. 1 1 Describe how the soil s water holding ability is affected by EACH of the following structures: i) crumb; ii) platy; iii) prismatic. 3 3 Q1 Candidates were expected to state what is meant by the terms field capacity and available water content. Candidates who stated that field capacity is the amount of water held in the soil after gravitational drainage, and available water as the amount of water held in a soil or growing media between field capacity and permanent wilting point scored full marks. Candidates were expected to describe how crumb, platy and prismatic structures affect water holding capacity, rather than simply defining the structures with no reference to water holding. Good candidates were able to describe how a good or a poor structure would influence water holding capacity. Answers on crumb structure produced good responses with candidates relating how the range of pore sizes in the structure, micropores, mesopores and macropores, lead to good water retention, as well as drainage. Candidates on occasions missed out on marks by incorrectly describing the roles of micropores, mesopores and macropores. Answers on platy structure that related to the slowing of drainage above pans, water being held in a horizontal plane and the soil having a higher water holding ability above the platy structure gained high marks. However, candidates who based their answers on surface capping of soils (rather than platy structures) were not awarded marks. Most candidates were able to describe prismatic structures, however, for high marks the relationship between a prismatic structure and the water holding capacity required stating. Low water holding capacity of prismatic structures is due to fast drainage of water between the columns along with the poor water holding capacity of the prismatic structures themselves due to their occurrence in heavy textured subsoils/b horizon. 4
Q Identify TWO of the main types of metamorphic rock found in the UK. State TWO characteristics of ONE of the rocks named in. c) Explain how TWO distinct weathering agents aid the breakdown of the parent rock to form soil. 6 Q Candidates were expected to state the names of two of the main types of metamorphic rock found in the UK. Candidates who gained full marks stated two of the following - slate, marble, schist or gneiss as their rock types. Some candidates confused metamorphic with igneous rocks, and so did not gain marks for this part of the question, and so also missed out on marks for ( Candidates were expected to state the characteristics of one of the rock types given in ( Slate was the most commonly chosen metamorphic rock and candidates who stated that slate has a fine- grained structure and that it is often split into thin plates scored full marks, as did those who described the minerals in slate as mainly clay and quartz, and the particles being very small in size. c) Candidates were expected to explain how two distinct weathering agents aid the breakdown of parent rock to form soil. Candidates could select from a variety of agents such as ice, wind, water, rain, heat and chemical and biological weathering agents. Candidates who were able to select two agents and describe their mode of action, i.e. rain wetting rock, the water entering cracks and fissures, freezing and expanding to exert pressure to force rock apart, scored full marks. Some candidates however wrote answers which stated multiple modes of action and lost marks as examiners in such circumstances apply the rubric (viii) that only the first answers which meet the question requirement will be accepted, regardless of the number of answers given, thus highlighting the importance of well-planned and logical answers. 5
Q3 State what is meant by the term 'cultivation window'. Explain how TWO factors affect the cultivation window of soils. 8 Q3 Candidates were expected to state what is meant by the term cultivation window. Candidates who correctly stated that a cultivation window is the window of opportunity where a soil can be cultivated without damage to its structure and that this will vary for different soil types scored full marks. Candidates were expected to explain how two factors could affect the cultivation window of soils. Distinctive answers clearly stated the factors as being soil structure, soil texture or moisture content/weather. A detailed answer would therefore state that the cultivation window is affected by the structure of the soil, would state an example soil structure, and discuss the timing of cultivation of a soil with this structure to maintain soil porosity, along with the importance of not damaging soil structure during cultivation. The importance of organic matter content and its role in creating strong peds which extended the cultivation window was also correctly mentioned by some candidates. The cultivation window is also affected by the texture of the soil, with fine textured soils being more prone to compaction, and the higher the clay content the greater the chance of smearing or compaction when wet which all narrow the window of cultivation, while a coarser textured soil with its lower water holding capacity and its lower likelihood of smearing and compaction has a wider window of cultivation. Some candidates failed to achieve high marks by discussing general soil cultivation practices, including the importance of adding organic matter without linking their answer to cultivation windows. 6
Q4 Explain how TWO factors affect the cultivation window of soils. 4 State SIX benefits to plants provided by the actions of soil bacteria. 6 Q4 Candidates were expected to describe the roles of bacteria and fungi in the breakdown of organic matter. Candidates who described the roles of the bacteria and fungi in the process rather than stating other factors such as the environmental requirements scored high marks. Distinctive answers included reference to the bacteria and fungi following after the initial breakdown by detritivores and macro organisms, with reference to the role of fungi in decomposing cellulose and lignin, and mineralisation by both types of organism, leading to the creation of humus. Candidates were expected to clearly state six benefits to plant of the action of soil bacteria. Candidates stating the fixation of nitrogen by free-living and symbiotic bacteria which increases the availability of nitrates to the plants, the role of nitrifying bacteria such as Nitrosomonas and Nitrobacter in producing nitrates which are easily absorbed by plants, the control of soil pests and pathogens, detoxification of herbicides and pesticides, and other relevant benefits scored high marks in this question. 7
Q5 State what is meant by cation exchange capacity. State what is meant by the term 'buffering capacity'. c) Describe the characteristics of a clay soil under EACH of the following headings: i) cation exchange capacity and nutrient availability; ii) buffering capacity and liming requirement. 4 Q5 Candidates were expected to state what is meant by the term cation exchange capacity Candidates who were able to give a full answer included the concept that cation exchange capacity (CEC) is the number of exchangeable cations a soil can hold and also more detailed information such as, at a given ph value, or high CEC prevents leaching of specific soil nutrients. Candidates were expected to state what is meant by the term buffering capacity with many candidates stating correctly that this is the soils ability to resist changes in ph. However, the second mark available was for a more developed answer including additional information such as, when the soil is acted upon by an alkaline or acidic agent. i) Candidates were expected to describe the key characteristics of a clay soil in relation to cation exchange capacity and nutrient availability. Candidates who linked high cation exchange and nutrient availability to the clay content in a soil gained full marks. Clay soils contain clay particles which have a negative surface charge and so attract positively charged cations; clay soils have a high cation exchange capacity and hold plant nutrient cations such as Calcium Ca++, Magnesium Mg++, Potassium K+ in an exchangeable manner. Candidates who went on to state that the high cation exchange capacity prevents nutrients being leached but allowed their exchange and uptake by plants were also credited. ii) Candidates were asked to describe the characteristics of a clay soil in relation to buffering capacity and liming requirement. Candidates who identified that clay soils have a high buffering capacity leading to a large amount of lime being required to change the ph, i.e. a high liming requirement, scored full marks. Candidates who stated that many clay soils have a high ph and so need little liming were also credited. 8
Q6 Describe for EACH of the following nutrients: i) ONE role within the plant; ii) TWO causes of deficiency. By completing the table below. Nutrient Calcium Magnesium Role in plant 1 1 Causes of deficiency 1 1 Describe how to rectify the deficiencies of EACH of the nutrients named in. 4 Q6 Candidates were asked to complete a table to describe the role of calcium and magnesium in the plant, along with the causes of deficiencies. Candidates who correctly stated the roles of the nutrients (for example calcium s role in cell wall production, or magnesium s role in chlorophyll production) scored full marks. The second part of the question related to the causes of deficiencies and so candidates who stated the deficiency symptoms did not score points. However, candidates who stated two causes of calcium deficiency such as erratic irrigation practices, acidic soils or calcium antagonism by potassium ions gained full marks. For magnesium deficiency candidates who stated two causes such as high levels of potassium, or excess calcium caused by over-liming, or low ph as an example, gained full marks. Candidates were expected to describe how to rectify the deficiencies of calcium and magnesium. Candidates who gave factual answers scored highly, for example stating improved irrigation practices and the addition of named calcium containing fertilisers or liming materials such as calcified seaweed or calcium carbonate scored full marks. Candidates who simply stated correct the soil ph and apply a fertiliser however did not provide sufficient factual content for marks to be awarded. Similarly, to rectify magnesium deficiency, candidates who stated that addition of magnesium sulphate (Epsom salts), named magnesium fertilisers, or dolomitic limestone could be used to correct a magnesium deficiency scored full marks. Whilst candidates who stated that an unnamed magnesium fertiliser should be used, or organic matter should be dug into the soil did not gain marks. 9
Q7 Describe what is meant by the term 'rhizosphere'. Describe how the specific properties of the rhizosphere benefit plant growth. 8 Q7 Candidates were asked to describe what is meant by the term rhizosphere. Candidates who stated that this is the area of the soil immediately adjacent to the root, or the area of soil within mm of the root gained a mark. A further mark was available for a developed answer, describing that this also the area where the soil chemistry and microbiology is influenced by the plant through root exudates. Candidates were expected to describe how the specific properties of the rhizosphere benefit plant growth. Candidates who clearly stated the properties of the rhizosphere and then linked these to their benefit to plant growth scored full marks. Examples of such an approach could include: The rhizosphere is a zone where the exudates from plant roots encourage mycorrhizal growth assisting the plant in water and phosphate uptake enabling increased plant growth. Some candidates, who based their entire answer on mycorrhiza and the mycorrhizal relationship with plant roots, missed out on marks for the other ways that the rhizosphere benefits plant growth. Other valid points included: The rhizosphere is often moister than the surrounding soil, leading to improved root growth and less plant stress. The rhizosphere has a greater number of microorganisms, whose activity results in a greater release of nutrients for plant use, leading to improved growth. The rhizosphere is often a zone where allelopathy deters the growth of competing plant roots, reducing competition and leading to better growth. 30
Q8 State SIX stages in the carbon cycle where carbon accumulates in the soil. MARKS 6 Explain the effects of cultivation on carbon storage in the soil. 4 Candidates were asked to state six stages in the carbon cycle where carbon accumulates in the soil. Candidates who stated that Plant residues Plant roots Animal faeces Macro- and micro-organisms Carbon fixed in peat or fossil fuels Humus were all ways that carbon accumulates in the soil scored full marks. Candidates were asked to explain the effects of cultivation on carbon storage in the soil. Candidates whose answers included: That cultivation releases carbon as it oxidises to carbon dioxide and is released to the atmosphere That cultivation damages roots, which then decay to release carbon That cultivation increases oxygen levels in the soil thus increasing aerobic microbial activity which in turn releases carbon That minimum tillage systems reduce the release of carbon scored full marks for this part of the question. The concept of carbon loss due to cultivation was demonstrated by most candidates, however the lack of applied horticultural/scientific reasoning surrounding this loss led to lower marks being awarded. 31
Q9 State TWO economic benefits for growers achieving certified organic status. Describe the limitations for growers of achieving certified organic status. 8 Q9 Candidates were asked to state two economic benefits for growers of achieving certified organic status. Most candidates stated that these were increased or premium prices, reduced input costs such as pesticides, and the development of a niche market. Candidates were asked to describe the limitations for growers of achieving certified organic status. Distinctive answers included the statement of clear limitations with further justification or reason, for example: The regular inspections and adherence to policy constraints having a cost implication. Organic production methods being more labour intensive, for example in relation to weed control outweighing the savings in reduced herbicide expenditure. The lower crop yields experienced in organic horticulture have a cost which has to be weighed up against the increase in price for the product. The sourcing of organic inputs can be time consuming and a lack of availability can be problematic and limit the grower. Some candidates failed to maximise on available marks through the use of vague generic terms such as sprays are not allowed, or all chemicals are banned. Whereas not all sprays are banned only those containing non-approved products are banned, and chemicals is a broad term, with naturally occurring chemicals being permitted. Some candidates lost out on marks by referring to copper as an approved product when it has been withdrawn for use as a garden fungicide. 3
Q10 Describe FIVE methods for managing potato blight, which are available to organic growers. MARKS 10 Q10 Candidates were asked to describe five methods of managing potato blight, which are available to organic growers. Most candidates gained high marks for this question giving descriptive details of five methods of managing potato blight. Correct answers included: Planting into clean land which has not previously grown potatoes will reduce the chance of soil borne infection. The selection of cultivars which are blight resistant will reduce the incidence of blight. The selection of certified seed potatoes will ensure that blight spores are not present on the tubers. Correct crop spacings will help the foliage to dry out after irrigation or rainfall and so reduce the incidence of blight. Timing of the crop through the use of earlier cultivars can be used as a technique to avoid crops being present in periods where blight infection could be at its height. It should be noted that some candidates lost out on marks by referring to copper as an approved product when it has been withdrawn for use as a garden fungicide. Candidates would be advised to research current practices in the production of organic crops, to ensure their knowledge of permitted products is up to date, along with app-based blight forecasting tools based on Smith s periods or Hutton s criteria and other technical developments. 33