Regional Workshops Managing and optimising the nutrition of bedding and pot plants

Transcription

1 Regional Workshops Managing and optimising the nutrition of bedding and pot plants Arden Lea Nurseries, 61 Moss Lane, Hesketh Bank, Preston, Lancashire 10 February 2016

2

3 Event Programme Time Presentation/topic Presenter 9.45 Coffee and registration Presentations Nutrient requirements of plants Neil Bragg Nutrient interactions Susie Holmes Tea and coffee Water quality and fertiliser types Neil Bragg Fertiliser programmes for bedding and pot plants and monitoring crops Lunch Susie Holmes Practical sessions Planning and monitoring interpretation of Susie Holmes analyses, use of conductivity meters, reactive/proactive feed programmes, fertiliser selection Optimising liquid feeding getting the most from your liquid feed dilutor, operation, maintenance, adjustment, dissolving nutrients into solution Neil Bragg onwards Q&A, tea and coffee, followed by optional tour of Arden Lea Nurseries AHDB Horticulture is a Division of the Agriculture and Horticulture Development Board (AHDB)

4 Contents Title Page Nutrient requirements of plants including essential plant nutrients exercise sheet. Neil Bragg 1 Nutrient interactions. Susie Holmes 2 Water quality and understanding fertilisers. Neil Bragg 8 Fertiliser programmes for bedding and pot plants and monitoring crops. Susie Holmes 12 Grower Notes Understanding the hardness of water 15 Planning and monitoring practical session example analytical reports Optimising liquid feeding practical session calibration of a dilutor Notes 24

5 Essential plant nutrients Nutrient Symbol Source Function Deficiency Toxicity Magnesium Mg Water, limestones, fertilisers, Epsom salts, kieserite Photosynthesis process Lower leaf chlorosis and bronzing Can upset calcium uptake Black 'given' Red essential in higher amounts Blue essential but in small amounts Green 'nice to have' for some plants 1

6 Nutrient interactions - Susie Holmes Nutrient interactions Effect of growing media and irrigation water. Deficiencies and toxicities. ph ph determines nutrient availability. ph = relative concentrations of H + & OH Peat based substrates maintain ph for most spp. Coir has naturally higher ph than peat so lime may not be needed. Hard water (high bicarbonate, >200 ppm) will cause the ph of the substrate to rise over time, lower starting ph may be enough if water only slightly hard but acidification necessary for higher bicarbonate water. Effect of ph on nutrient availability FACTS Cation exchange capacity CEC = the ability of the growing medium to hold and release cations (positively charged ions) e.g. K+, Mg+ due to more surfaces with negative charges for cations to stick to. Bark has a higher CEC than peat. Higher CEC is good buffer against high or low nutrient levels esp. for young plants/salt sensitive species. 2

7 Nutrient interactions - Susie Holmes Cyclamen in peat/bark mix Nutrient interactions With similar size nutrient ions, e.g. Ca, K, Mg ions, high levels of one may reduce uptake of another, e.g. High K level may inhibit Mg uptake. High ammonium levels inhibit Ca uptake (affects water uptake by roots). Plants fed with high nitrogen feed will take up more N and less K > softer growth. High P levels inhibit uptake of Zn, Mn and Fe. Substrate interactions Poor capillary movement of water High lignin material (e.g. bark, wood fibre and coir) can cause N immobilisation as microbes break them down and use up N. Coir is naturally high in K but levels reduce in use. Substrate structure will affect water uptake and hence nutrient availability good capillary action needed for sub irrigation but must drain well too. Media with a naturally high EC due to high chloride levels can lead to nutrient imbalance. Bark increases CEC of a peat mix = more buffering of nutrient levels. Poor nutrient uptake due to poor substrate structure Nitrogen Deficiency is most common when CRF has run out/plants have been kept longer than anticipated. Temporary N deficiency is common in mixes with bark/woody material when these are broken down by microbes which then use up plant available N. Deficiency causes generally weaker growth, yellowing starts on older leaves and then progresses to rest of plant. Reddish tints may be seen also in deficient leaves. Woody shrubs typically need mg N per week. N deficiency decreases the plant s ability to take up P, K, S and Mn. High N levels can promote soft growth which is more prone to disease/cold damage. 3

8 Nutrient interactions - Susie Holmes Geranium nitrogen deficiency Marigold reducing nitrogen levels Ammonium toxicity Petunia mild ammonium toxicity Most common when organic or slow release forms of N used and ammonium not broken down quickly by bacteria to nitrate N. Plants can take up ammonium N but too much is toxic, especially for young plants/low light. Ammonium toxicity induces calcium deficiency and damages roots. Salvia calcium deficiency induced by high ammonium level Phosphorus Deficiency rarely seen. Mycorrhizal associations are important in P nutrition, especially for woody species. P appears to have a beneficial effect in control of root pathogens. Some species are sensitive to high P levels. e.g. Azalea, Hydrangea symptoms are pale leaves/chlorosis (leaf P level of over 0.3 mg/l in susceptible species may indicate toxicity). 4

9 Nutrient interactions - Susie Holmes Potassium Begonia potassium deficiency Deficiency rarely seen but shows as marginal yellowing/brown spotting of older leaves. Lower N/higher K regimes tend to favour harder growth and better flowering because K is involved in sugar metabolism. Potassium has a role in disease tolerance. High K levels can hinder uptake of Mg (similar size ions). Magnesium Hydrangea magnesium deficiency Deficiency is usually due to poor uptake rather than an actual lack of Mg. Mg deficiency can be induced by poor root health or erratic water availability. High K levels can hinder uptake of Mg. Hellebore/poinsettia magnesium deficiency Calcium Deficiency is nearly always due to poor uptake rather than an actual lack of Ca. Ca deficiency is often induced by low transpiration rates (high humidity/lack of air movement) because it moves in the xylem and water isn t being pulled through the plant. Foliar Ca sprays can help as will better ventilation/fans/better spacing of plants. Typical symptoms are seen at furthest point from roots e.g. leaf tips (scorch/tip burn). 5

10 Nutrient interactions - Susie Holmes Poinsettia calcium deficiency induced by high EC Begonia calcium deficiency Iron Deficiency is nearly always due to poor uptake rather than an actual lack of Fe. Fe deficiency is often induced by high ph or fine root damage (due to high EC or waterlogging). Foliar chelated iron sprays can help but avoid spraying in hot sunny weather and will need repeating. Symptoms seen in the youngest leaves yellowing/bleaching of leaves. Petunia iron deficiency Poinsettia/gerbera iron deficiency Manganese Usually induced by high ph (and sometimes anaerobic growing medium). Often seen in conjunction with Fe deficiency but on slightly older leaves. Yellowing is more mottled than with Fe deficiency. 6

11 Nutrient interactions - Susie Holmes Poinsettia manganese deficiency Molybdenum Poinsettia are susceptible but rarely seen as provided by fertiliser. The only nutrient that is less available at low ph. Causes leaf distortion. Poinsettia molybdenum deficiency 7

12 Water quality and understanding fertilisers - Neil Bragg Water quality and understanding fertilisers Water quality Know the source borehole, roof water collection, river extraction, mains water. Measure the alkalinity (bicarbonate equivalence, or temporary hardness i.e. the liminess of water). See attached Grower Note on water quality. Levels of alkalinity Water Type Alkalinity (ppm) Need for treatment Soft <125 No Hard Worth considering Very hard Yes Extremely hard >301 Yes also worth looking at alternative sources Methods of correction of alkalinity Dilution with softer water such as glasshouse run off from roof. Use of acid injection, nitric, phosphoric or citric: Extreme care needed in use of any acid. Handling of concentrate and the avoidance of spillage essential. PPE need to be used. Examples of acid injection Understanding fertilisers By law, all products sold as fertiliser require uniform labelling guaranteeing the minimum percentage of nutrients. The three number combination (fertiliser grade or analysis) on the product identifies percentages of nitrogen (N), phosphate (P2O5), and potash (K2O), respectively. For example, a fertiliser contains 20% nitrogen, 10% phosphate, and 5% potash. Fertiliser ratio indicates a comparative proportion of nitrogen to phosphate to potash. For example, a fertiliser has a ratio of 3 2 1, and an fertilizer has a ratio of Fertiliser recommendations from a soil test are given in ratios. 8

13 Water quality and understanding fertilisers - Neil Bragg Label declarations Typical label declarations Statutory declaration Fertiliser packaging is required by law to include a number of details, including the following: The prescribed name of the product content, such as NPK Fertiliser. The major nutrient contents, nitrogen (N), phosphorus (P) and potassium (K). Forms in which the nitrogen content is present. Solubility of the phosphorus content: P and K are usually expressed as their oxide content, followed in brackets by the content of the element. Levels of secondary nutrients present such as magnesium (Mg) and other trace elements in alphabetical order, B, Cu,Fe, etc. The name and address of the manufacturer. The guaranteed weight of the product. An EC product declaration, if the product is EC approved. The chemistry Conversion information Nutrient content can be expressed in two ways: 1) Elemental: Potassium; K Phosphorus: P 2) Oxide: Potassium oxide; K 2 O A B A to B B to A Nitrogen % (N) Ammonia (NH 4 ) Nitrogen % (N) Nitrate (NO 3 ) Phosphorus % (P) Phosphorus pentoxide (P 2 O 5 ) Potassium % (K) Potassium oxide (K 2 O) Magnesium % (Mg) Magnesium oxide MgO Phosphorous pentoxide P 2 O 5 Granulated Prilled Powdered Pelleted Coated Preparations Fertiliser types STRAIGHTS Applied to materials like potassium nitrate, ammonium nitrate and magnesium sulphate. One type of fertiliser not one element. COMPOUNDS Mixture of various straight fertiliser crystals. Potassium nitrate + ammonium nitrate = compound containing K, NO 3 and NH 4 9

14 Water quality and understanding fertilisers - Neil Bragg Fertiliser types BASE Supply base nutrients to a mix for readily available supply and trace elements. A fine ground compound containing N, P, K and TEs. WATER SOLUBLE FERTILISERS (powder/crystals/tablets) Used in production of liquid feeds; readily soluble in water. Fast acting, short term control, can leach out easily. Good as a foliar feed. PG Mix Peters Excel Release patterns Slow release or controlled release Nutrient release controlled by: Temperature of growing media Moisture content of growing media Longevity controlled by: Thickness of the coating Type of coating Time release Nutrient release controlled by: Breakdown of product through biological action Water soluble Nutrient release immediate Osmocote Basacote Nutricote Multicote Mannacote Plantacote Minerva HortiBase Polyon Sinchron Floranid Permanent Enmag Nitroform Sangral Peters Solufeed Vitafeed Nutrients Dissolving nutrients Nutrients in fertiliser products Nitrogen % Phosphate Product % Potash % Ammonium nitrate Ammonium sulphate Urea Calcium ammonium nitrate Calcium nitrate Di-ammonium phosphate Mono-ammonium phosphate (MAP) Single Super-phosphate (SSP) Potassium nitrate Potassium sulphate Potassium-magnesium sulphate Solubility table grm/100ml Cold Hot Ammonium nitrate Calcium nitrate Urea 78 Mono ammonium phosphate Potassium nitrate Magnesium sulphate Sodium borate 1 14 Ferrous sulphate Sodium molybdate Liquid feeding equipment Liquid feeding equipment 10

15 Water quality and understanding fertilisers - Neil Bragg Liquid feeding equipment Liquid feeding equipment conductivity controlled 11

16 Fertiliser programmes - Susie Holmes Fertiliser programmes for bedding and pot plants and monitoring crops Matching supply to demand Fertiliser programmes for bedding plants Two main systems: Base fertiliser + liquid feed as needed (accurate distribution needed especially for small modules). Low rate base fertiliser + controlled release fertiliser (CRF). CRF: 3 4 month product adds shelf life. Care needed with rate if potting very small plugs. Unusually hot weather can cause fast release. Base fertiliser Typically used at kg/cu m useful for supplying nutrients quickly after potting (last 4 6 weeks). Can be useful for adding some extra nitrogen with mixes that tend to immobilise N (e.g. calcium nitrate in bark or wood fibre mixes) but longerterm supplementary needed too. Be careful about using for salt sensitive spp. Different N:P:K ratios available but only short term nutrition being supplied. Liquid feed types Chose nutrient ratio (N:P:K) to suit the crop: 3:1:1 high N feed for starved crops. 3:1:3 balanced feed. 1:1:3 high K feed for flowering/slower growing spp. 3:1:6 high K plus moderate N feed for vigorous spp. Using nutrition to control growth Higher EC = reduces water uptake = shorter internodes (more compact plants). Low phosphorus level reduces plant growth (P needed for root growth). Feeding with higher potassium feed and less nitrogen gives less soft growth than high N feed. A balanced feed applies NPK in a ratio plants require them e.g. 3:1:3, not 1:1:1. Dosatron for liquid feeding 12

17 Fertiliser programmes - Susie Holmes Liquid feeding overhead irrigation system Fertiliser programmes for pot plants Most pot plants grown with liquid feed system. Efficiency of nutrient delivery is linked to efficiency of irrigation system. Foliar feeds are good for treating problems due to poor uptake e.g. calcium, trace element deficiencies. Poorer crop in dry area Better root system provides better nutrition Liquid feeding Typical sub irrigation system Accurate irrigation needed for accurate feeding. Monitoring essential of feed and crop requirements. Water high in bicarbonate may need acidifying to maintain nutrient availability (for moderately hard water acidifying feeds can be useful). Soft water may need extra Ca/Mg in feed. 13

18 Fertiliser programmes - Susie Holmes Monitoring nutrition growing media analysis Monitor leaf colour/growth, backed up by analyses. Particularly important when growing medium has changed/new crops/high value crops. Regular analysis useful to determine best nutrient regime for key crops. Monitoring nutrition growing media analysis (cont.) ph (ideally ). Electrical Conductivity (ideally microsiemens/cm depending on crop and stage). Ammonium N no higher than 100 mg/l. N,P, K, Mg Index 1 4. Trace elements water extract growing media analysis no use leaf analysis needed. Monitoring nutrition EC meters Need to calibrate meter correctly. Meter readings won t be the same as laboratory readings but can give general guide to nutrient status of crop. Moisture content of growing medium at time of taking sample will affect reading unless sample is diluted with distilled water as for lab readings (1:5). EC reading on run off can be useful but needs practice to carry out and interpret results (e.g. USA pour through method). Monitoring nutrition leaf analysis Useful for diagnosing trace element problems (often due to poor uptake rather than lack of supply) but not for iron deficiency. Need reference data for the crop to compare with. Generally a growing medium analysis is also needed to check ph and nutrient levels. 14

19 GROWER NOTES UNDERSTANDING THE HARDNESS OF WATER The hardness of water is very much dependent on the origins of the water: rainwater is soft, but having fallen onto differing geological deposits, its nature can be radically altered. For example, many people in the Manchester area receive water that has fallen onto the acidic hard rocks of the Lake District and their water is very soft. Conversely, people living in much of the South East receive water which drawn from boreholes sunk into deep chalk aquifers which yield extremely hard water. There are two types of water hardness: 1. Permanent Hardness the result of high levels of insoluble sulphate compounds. 2. Temporary Hardness the results of differing level of dissolved magnesium and Calcium Carbonates and Bicarbonates. The Temporary Hardness can be equated to a lime wash solution and the higher the value then the greater the chances of: Blocked nozzles Lime scale on leaves ph rise in the substrate To find out how hard your water is, you need a complete water analysis, to include: ph plus all major elements N, P, K, Ca, Mg, Na, etc. plus the Trace Elements Fe, Mn, Zn, Cu, etc. plus you need to know the Temporary Hardness, which is also described by some as the Alkalinity or Bicarbonate equivalent. So how hard is your water? WATER TYPE ALKALINITY/BICARB NEED FOR TREATMENT LEVEL ppm SOFT <125 No HARD Worth considering VERY HARD Yes EXTREMELY HARD >300 Yes but better to find softer water Note ph of the water is not a guide to its hardness all mains water and many natural sources have a ph of 7+ or are adjusted to 7+ by water companies. With acid dosing systems, the problem is that the change in hardness is monitored by changes in ph but in itself this is not a guide to the level of hardness. The key effects of hard water are: ph in compost may rise during use and restrict nutrient uptake, leading to pale/chlorotic plants. The solubility of Water Soluble Fertilisers may be adversely affected. There may be difficulty in dissolving fertilisers, leading to potential blockage of nozzles. Wetting Agents in composts may not be so effective due to the increasing liminess of the compost. Use of acid to reduce hardness may lead to a nutrient imbalance. Use of acid during water treatment has serious safety/handling implications the Health & Safety Executive produce guidelines on the safe use of acid. Bulrush Horticulture Ltd, Newferry Road, Bellaghy, Magherafelt, Co. Derry BT45 8ND Telephone: +44 (0) Facsimile: +44 (0) bulrush@dial.pipex.com Website: GN25 July

20 Example 1 Mains water Please quote above code for all enquiries WATER ANALYSIS RESULTS Sample Reference : MAINS Sample Matrix : WATER Report Number Sample Number Laboratory References Date Received Date Reported The sample submitted was of adequate size to complete all analysis requested. The sample will be kept under refrigeration for at least 3 weeks. ANALYTICAL RESULTS on as received basis. Determinand Value Units Determinand Value Units ph 7.20 Conductivity 714 us/cm Nitrate-N 6.0 mg/l Chloride 90.3 mg/l Sulphate as SO mg/l Total Phosphorus as P 1.2 mg/l Boron < 0.01 mg/l Potassium 6.4 mg/l Magnesium 13.9 mg/l Calcium 61.6 mg/l Sodium 64.3 mg/l Carbonate < 0.1 mg/l Alkalinity as HCO mg/l TDS mg/l ph and Conductivity measurements are made at 20 C. I.S. = Insufficient Sample. Released by... Date... 16

21 Example 2 - Borehole water Please quote above code for all enquiries Sample Reference : BOREHOLE Sample Matrix : WATER WATER ANALYSIS RESULTS The sample submitted was of adequate size to complete all analysis requested. The sample will be kept under refrigeration for at least 3 weeks. ANALYTICAL RESULTS on as received basis. Report Number Sample Number Laboratory References Date Received Date Reported Determinand Value Units Determinand Value Units ph 7.50 Conductivity 1710 us/cm Nitrate-N 1.3 mg/l Chloride 32.2 mg/l Sulphate as SO mg/l Total Phosphorus as P 0.4 mg/l Boron 0.40 mg/l Potassium 4.2 mg/l Magnesium 69.2 mg/l Calcium mg/l Sodium 74.1 mg/l Carbonate < 0.1 mg/l Alkalinity as HCO mg/l TDS mg/l 17

22 Example 3 Growing media Please quote above code for all enquiries Sample Reference : POINSETTIA Sample Matrix : ANALYTICAL RESULTS COMPOST ANALYSIS RESULTS COMPOST The sample submitted was of adequate size to complete all analysis requested. The sample will be kept under refrigeration for at least 3 weeks. on as received basis. Report Number Sample Number Laboratory References Date Received Date Reported Determinand Value Units Determinand Value Units ph 6.49 Cond. at 20 C 67 us/cm Density 481 kg/m3 Ammonia-N 4.7 mg/l Dry Matter 25.2 % Nitrate-N 8.3 mg/l Dry Density kg/m3 Total Soluble N 13.0 mg/l Chloride 18.3 mg/l Sulphate 36.3 mg/l Phosphorus 10.2 mg/l Boron 0.17 mg/l Potassium 51.9 mg/l Copper < 0.06 mg/l Magnesium 4.5 mg/l Manganese < 0.06 mg/l Calcium 4.3 mg/l Zinc < 0.06 mg/l Sodium 16.5 mg/l Iron 0.29 mg/l The extraction is performed by adding a weight of sample equivalent to 60mls volume to 300mls of deionised water (ref BSEN 13652:200 1 Samples submitted under 1 litre will necessitate the use of scaled down equipment for density determination. 3 ph and Conductivity measurements are made at 20 C. I.S. = Insufficient Sample. Released by... Date....nrm.uk.com 18

23 COMPOST ANALYSIS RESULTS Example 4 Growing media Sample Reference : TERRACOTTA Sample Matrix : COMPOST The sample submitted was of adequate size to complete all analysis requested. The sample will be kept under refrigeration for at least 3 weeks. Report Number Sample Number Date Received Date Reported ANALYTICAL RESULTS on as received basis. Determinand Value Units Determinand Value Units ph 4.54 Conductivity 692 us/cm Density 479 kg/m3 Ammonia-N 20.1 mg/l Dry Matter 29.7 % Nitrate-N mg/l Dry Density kg/m3 Total Soluble N mg/l Chloride 60.8 mg/l Sulphate mg/l Phosphorus 92.4 mg/l Boron 0.40 mg/l Potassium mg/l Copper 0.18 mg/l Magnesium mg/l Manganese 2.49 mg/l Calcium mg/l Zinc 0.46 mg/l 19

24 Example 5 Growing media Please quote above code for all enquiries COMPOST ANALYSIS RESULTS Sample Reference : POINSETTIA Sample Matrix : COMPOST Report Number Sample Number Laboratory References Date Received Date Reported The sample submitted was of adequate size to complete all analysis requested. The sample will be kept under refrigeration for at least 3 weeks. ANALYTICAL RESULTS on as received basis. Determinand Value Units Determinand Value Units ph 4.77 Conductivity 417 us/cm Density 426 kg/m3 Ammonia-N 22.7 mg/l Dry Matter 25.6 % Nitrate-N mg/l Dry Density kg/m3 Total Soluble N mg/l Chloride 42.3 mg/l Sulphate mg/l Phosphorus 41.7 mg/l Boron 0.21 mg/l Potassium mg/l Copper 0.11 mg/l Magnesium 99.9 mg/l Manganese 0.39 mg/l Calcium mg/l Zinc 0.34 mg/l Sodium 35.0 mg/l Iron 1.61 mg/l Water Soluble nutrients determined by a 1:6 v/v extraction in deionised water to BSEN13652:2001. Samples submitted under 1 litre will necessitate the use of scaled down equipment for density determination. ph and Conductivity measurements are made at 20 C. I.S. = Insufficient Sample. 3 Released by... Date... 20

25 Example 6 Leaf tissue 21

26 22

27 23

28 Notes 24

29 Notes 25

30 Notes 26

31

32 AHDB Horticulture is a Division of the Agriculture and Horticulture Development Board (AHDB)