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Rhs level 2 certificate year 2 week 8

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    Rhs level 2 certificate year 2 week 8 Rhs level 2 certificate year 2 week 8 Presentation Transcript

    • RHS Level 2 Certificate Year 2 Week 8 – fertilizers and alternative growing media.
    • Learning objectives - fertilizers
      • 7.6 State what is meant by the terms ‘organic fertiliser’ and ‘inorganic fertiliser’ and list TWO examples of EACH.
      • 7.7 State TWO benefits and TWO limitations of using organic fertilisers and inorganic fertilisers.
      • 7.8 State what is meant by: single or straight fertilisers; compound fertilisers. List TWO examples of EACH
      • 7.9 State what is meant by the terms
      • ‘ Base dressing’, ‘Top dressing’, ‘Liquid feed’ and ‘Foliar feed’. Describe ONE situation where EACH type of fertiliser application would be appropriate.
      • 7.10 Describe the use of Controlled Release Fertiliser (CRF) granules and state TWO benefits and TWO limitations of their use in growing media.
    • Learning objectives – alternative growing media
      • 8. Understand the uses of alternative growing media
      • 8.1 Describe the range of compost types available, and the use of EACH of these growing media as alternatives to growing in soil: including peat-based, loam-based, peat-free, multipurpose, ericaceous, seed and cutting and container composts.
      • 8.2 State how air-fill porosity, water holding capacity, and stability of growing media affect plant growth
      • 8.3 Describe the environmental implications of the use of peat, coir and municipal green waste in growing media.
    • Fertilizers – soil testing
      • Three approaches
      • Rule of thumb – suitable for non-cropping situations.
      • Follow fertilizer intervals recommended – e.g. N each year perhaps several times, P annually and K every second or third year.
      • Soil testing – macro only (DIY) or full nutrient analysis via laboratory. Required to diagnose excess/deficiency accurately.
    • Fertilizers – organic and inorganic
      • Organic fertilizers are made from once living materials (Fish, Blood and Bone etc).
      • Inorganic fertilizers are derived from non-living sources such as rocks (Phosphate) or by synthesis from fossil fuels (e.g. Nitrogen via the Haber process).
      • Do not confuse with ‘organic’ growing practices
      • Fertilizers may be ‘straight’ (single nutrient) or ‘compound’ (more than one nutrient).
    • Organic fertilizers – sources and characteristics Potassium – the only organic source of potassium at about 6% by dry weight Wood ash Contains all three macro-nutrients (with the potassium coming from rock potash) 5:5:6 Fish, blood and bone (compound) Some Nitrogen, mostly phosphorous, no potassium. 4:15:0 (4% N: 15%P;0% K) Bone meal – heat treated crushed animal bone. A compound fertilizer Characteristics Fertilizer
    • Organic fertilizers – advantages and disadvantages May attract vermin. Encourages beneficial soil organisms Powder (meal) less easy to spread evenly Lower soil salinity after use Low concentrations of nutrients per volume Recycles food production waste Requires microbial activity Slow release – so less risk of leaching Disadvantages Advantages
    • Inorganic fertilizers – sources and characteristics 7: 7: 7 (7% N: 7% P and 7% K) Growmore (compound) 60% Potassium Potassium Chloride (Straight) 43% Phosphorous Triple Super Phosphate (Straight) About 16% N by dry weight (as nitrate) Sodium Nitrate (Straight)
    • Inorganic fertilizers – advantages and disadvantages ‘ Straights’ are easy to over apply Cheap Increases soil salinity with regular use. Very concentrated so less needed Will leach readily if applied at the wrong time or in excess. Water soluble –so soil temperature not crucial High consumption of fossil fuels – releasing CO2. Easy to get exactly what is required
    • Application methods
      • Base Dressing – applied before planting
      • Top Dressing – applied to existing planting.
      • Foliar Feed – solution sprayed onto and taken up by the leaves.
      • Liquid feed – solution applied diluted to the growing media or soil.
      • Controlled Release Granules or tablets – compound fertilizer in polymer shell. Release over time triggered by soil temperature.
    • CRF – advantages and limitations Not ideal for open ground – due to above. Avoids high salinity in containers – unlike liquid feed Single application – hard to adjust later Single application – less work Polymer remains in soil and decomposes slowly Reduced leaching Expensive Release linked to soil temperature and growth rates.
    • Alternative Growing Media – basic concepts
      • Air Filled Porosity – the percentage of pores in the growing media that will hold air once gravitational water has drained.
      • Water Holding Capacity – used to describe the water content after drainage.
      • Bulk Density – weight per unit volume
      • Stability – ability of the media to form and retain a good structure over time.
    • Nutrient Content and pH
      • The nutrient content of growing media varies according to their use. For example cuttings compost contains no added nutrients and seed compost very little (perhaps a little added phosphate). Multi-purpose compost contains N, P and K.
      • pH varies though most are approximately neutral. Calcifuges will need ericaceous compost which is acidic.
    • Materials used – Peat based
      • Has good AFP and low Bulk Density, making it cheap to transport. Good WHC but hard to re-wet once dried out. Usually contains re-wetting agent because of this.
      • Peat contains no nutrients of its own so it is easy to add what is required.
      • Environmentally problematic due to destruction of wetlands and CO2 emissions from processed peat and drained bogs.
    • Materials – peat alternatives
      • Coir – made from coconut husks; good AFP and WHC. Re-wets easily, unlike peat. Low Bulk Density. Has been criticised for relatively rapid decomposition though this may be down to quality. Low in nutrients in original state
      • Wood waste – composted bark or sawdust. Good AFP and WHC. Higher Bulk Density than peat or coir. Low in nutrients.
      • Composted Green Waste – variable AFP and WHC (though British Standard now introduced). High in nutrients so not suitable for seed or cuttings mixes.
    • Loam based growing media
      • John Innes is the name of a standard formulation – not a brand name.
      • There are JI seed, cuttings, potting and general use composts.
      • Based on sieved loam, peat and sand with added lime and variable amounts of JI Base Fertilizer depending on use.
      • High Bulk Density makes them suitable for long term planting (but harder to handle and more expensive to transport); medium AFP and good WHC (dry out less easily than organic media).
      • Ericaceous version available.
    • Learning Outcomes - Fertilizers
      • 7.6 State what is meant by the terms ‘organic fertiliser’ and ‘inorganic fertiliser’ and list TWO examples of EACH.
      • 7.7 State TWO benefits and TWO limitations of using organic fertilisers and inorganic fertilisers.
      • 7.8 State what is meant by: single or straight fertilisers; compound fertilisers. List TWO examples of EACH
      • 7.9 State what is meant by the terms
      • ‘ Base dressing’, ‘Top dressing’, ‘Liquid feed’ and ‘Foliar feed’. Describe ONE situation where EACH type of fertiliser application would be appropriate.
      • 7.10 Describe the use of Controlled Release Fertiliser (CRF) granules and state TWO benefits and TWO limitations of their use in growing media.
    • Learning Outcomes – Alternative Growing Media
      • 8. Understand the uses of alternative growing media
      • 8.1 Describe the range of compost types available, and the use of EACH of these growing media as alternatives to growing in soil: including peat-based, loam-based, peat-free, multipurpose, ericaceous, seed and cutting and container composts.
      • 8.2 State how air-fill porosity, water holding capacity, and stability of growing media affect plant growth
      • 8.3 Describe the environmental implications of the use of peat, coir and municipal green waste in growing media.