Argus Nutrient Dosing Handbook July 27, 2017 Argus Nutrient Dosing Handbook Copyright 2017 Argus Control Systems Ltd This publication may not be duplicated in whole or in part by any means without the prior written permission of Argus Control Systems Ltd. Limits of Liability and Disclaimer of Warranty: The information in this manual is furnished for informational use only and is subject to change without notice. Although our best efforts were used in preparing this book, Argus Control Systems Ltd assumes no responsibility or liability for any errors or inaccuracies that may appear. Trademarks: Argus Controls, Argus Graph, Argus Control Systems, Argus Titan, and the Argus logo are trademarks of Argus Control Systems Ltd. Argus Control Systems Ltd. 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Revised July 2017 Table of Contents Argus Nutrient Dosing Handbook........................................................... 5 About this Manual ................................................................................................ 5 General Safety precautions.................................................................... 6 Backflow Prevention............................................................................................. 6 Handling Acids & Bases....................................................................................... 6 Pesticide Injection and Chemigation.................................................................... 7 Avoiding Mixing Errors ......................................................................................... 7 Security & Safety.................................................................................................. 9 Irrigation Water Quality......................................................................... 10 Water Analysis ................................................................................................... 11 Understanding pH Control.................................................................... 13 What is pH?........................................................................................................ 13 Acids and Bases ................................................................................................ 13 Why does pH Matter? ........................................................................................ 14 Why Adjust Irrigation pH? .................................................................................. 15 Understanding The pH Scale............................................................................. 15 Understanding Alkalinity and Buffering Capacity ............................................... 17 Alkalinity Testing ................................................................................................ 19 Measuring pH..................................................................................................... 19 pH Sensor Life and Maintenance....................................................................... 20 pH Reaction Time .............................................................................................. 20 Factors Affecting pH........................................................................................... 21 Working with Acids and Bases ............................................................. 23 Safety Precautions when Handling Acids and Bases ........................................ 23 Altering pH in the Root Zone.............................................................................. 23 Methods for Raising pH...................................................................................... 24 Methods of Lowering pH .................................................................................... 24 Residues and Precipitates ................................................................................. 25 Acids Used for pH Control.................................................................................. 25 Calculating How Much Acid You Need .............................................................. 26 Acid Titration Curves.......................................................................................... 30 Pre-dilution of Acid/Base Concentrates ............................................................. 31 Soluble Fertilizers used for Liquid Plant Feeding ................................. 34 The Essential Plant Nutrients............................................................................. 34 - 1 - © 2016 Argus Control Systems Limited Law of Limiting Factors ...................................................................................... 35 Fertilizer Antagonisms........................................................................................ 35 Composition of Soluble Fertilizers...................................................................... 36 Electrical Conductivity of Fertilizer Solutions........................................ 37 Soluble Salts ...................................................................................................... 37 Understanding Osmosis..................................................................................... 38 Understanding Reverse Osmosis ...................................................................... 39 What is Electrical Conductivity?......................................................................... 39 Limitations of EC Measurement......................................................................... 40 Measuring EC .................................................................................................... 41 Salt Index ........................................................................................................... 43 Fertilizer Compatibility........................................................................................ 44 The Jar Test....................................................................................................... 45 Measuring Fertilizer Concentration ...................................................... 46 Weight per Weight (Parts per Million) ................................................................ 46 Weight per Volume (Grams, Milligrams, or Micrograms per litre) ...................... 47 Equivalent Weight Units (meq/L - milliequivalents per litre)............................... 47 Moles and Millimoles.......................................................................................... 47 Working With Feeding Formulas Based on Molar Values.................... 49 Example ............................................................................................................. 49 Make Your Own or Purchase Premixed Fertilizers? ............................ 50 Fertilizer Source Selection ................................................................... 51 Fertilizer Calculations ........................................................................... 52 PPM (Parts Per Million Required) ...................................................................... 52 Elemental Content.............................................................................................. 52 Litres Required................................................................................................... 53 The Concentration Factor .................................................................................. 53 Some Example Fertilizer Calculations ............................................................... 54 Preparing a Complete Fertilizer Solution.............................................. 56 Working with Concentration Ratios ...................................................... 64 Nutrient Injection Basics....................................................................... 65 Batch Mixing....................................................................................................... 65 Automatic Dilution Systems ............................................................................... 66 Dilute Blending Tank Control ............................................................................. 66 Pressurized In-line Injection............................................................................... 67 The Problem of Turndown.................................................................................. 67 Complete’ Feeds .................................................................................. 68 A/B Mixes........................................................................................................... 68 Single Element’ Dosing ........................................................................ 70 Stock Concentrate Tanks & Fittings ..................................................... 71 Materials Selection............................................................................................. 71 - 2 - © 2016 Argus Control Systems Limited Calculating and Calibrating Stock Tank Volumes ................................ 73 Calculating Volumes of Rectangular Shapes..................................................... 74 Cylindrical shapes (inside measurements): ....................................................... 74 Other Shapes....................................................................................................