NQF Level: 3 US No:

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1 NQF Level: 3 US No: Learner Guide Primary Agriculture Maintain Water Quality Parameters My name: Company: Commodity: Date: The availability of this product is due to the financial support of the National Department of Agriculture and the AgriSETA. Terms and conditions apply.

2 2 Before we start Dear Learner - This Learner Guide contains all the information to acquire all the knowledge and skills leading to the unit standard: Title: Maintain Water Quality Parameters US No: NQF Level: 3 Credits: 2 The full unit standard will be handed to you by your facilitator. Please read the unit standard at your own time. Whilst reading the unit standard, make a note of your questions and aspects that you do not understand, and discuss it with your facilitator. This unit standard is one of the building blocks in the qualifications listed below. Please mark the qualification you are currently doing: Title ID Number NQF Level Credits Mark National Certificate in Animal Production National Certificate in Plant Production Please mark the learning program you are enrolled in: Your facilitator should explain the above concepts to you. Are you enrolled in a: Y N Learnership? Skills Program? Short Course? This Learner Guide contains all the information, and more, as well as the activities that you will be expected to do during the course of your study. Please keep the activities that you have completed and include it in your Portfolio of Evidence. Your PoE will be required during your final assessment.

3 3 What is assessment all about? You will be assessed during the course of your study. This is called formative assessment. You will also be assessed on completion of this unit standard. This is called summative assessment. Before your assessment, your assessor will discuss the unit standard with you. Assessment takes place at different intervals of the learning process and includes various activities. Some activities will be done before the commencement of the program whilst others will be done during programme delivery and other after completion of the program. The assessment experience should be user friendly, transparent and fair. Should you feel that you have been treated unfairly, you have the right to appeal. Please ask your facilitator about the appeals process and make your own notes. How to use the activity sheets Your activities must be handed in from time to time on request of the facilitator for the following purposes: The activities that follow are designed to help you gain the skills, knowledge and attitudes that you need in order to become competent in this learning module. It is important that you complete all the activities and worksheets, as directed in the learner guide and at the time indicated by the facilitator. It is important that you ask questions and participate as much as possible in order to play an active roll in reaching competence. When you have completed all the activities and worksheets, hand this workbook in to the assessor who will mark it and guide you in areas where additional learning might be required. You should not move on to the next step in the assessment process until this step is completed, marked and you have received feedback from the assessor. Sources of information to complete these activities should be identified by your facilitator. Please note that all completed activities, tasks and other items on which you were assessed must be kept in good order as it becomes part of your Portfolio of Evidence for final assessment. Enjoy this learning experience!

4 4 How to use this guide Throughout this guide, you will come across certain re-occurring boxes. These boxes each represent a certain aspect of the learning process, containing information, which would help you with the identification and understanding of these aspects. The following is a list of these boxes and what they represent: What does it mean? Each learning field is characterized by unique terms and definitions it is important to know and use these terms and definitions correctly. These terms and definitions are highlighted throughout the guide in this manner. You will be requested to complete activities, which could be group activities, or individual activities. Please remember to complete the activities, as the facilitator will assess it and these will become part of your portfolio of evidence. Activities, whether group or individual activities, will be described in this box. Examples of certain concepts or principles to help you contextualise them easier, will be shown in this box. The following box indicates a summary of concepts that we have covered, and offers you an opportunity to ask questions to your facilitator if you are still feeling unsure of the concepts listed. My Notes You can use this box to jot down questions you might have, words that you do not understand, instructions given by the facilitator or explanations given by the facilitator or any other remarks that will help you to understand the work better

5 5 What are we going to learn? What will I be able to do?... 6 Learning Outcomes... 6 What do I need to know Water quality An Introduction... 7 Session 1: Interpreting parameters and abnormalities in water quality Session 2: Critical control points in water quality management Session 3: Water quality management systems Session 4: Concept of quality management systems Am I ready for my test? Checklist for Practical assessment Paperwork to be done Bibliography Terms and Conditions Acknowledgements SAQA Unit Standard

6 6 What will I be able to do? When you have achieved this unit standard, you will be able to: Maintain water quality and adjust systems to ensure appropriate water quality. Read, record and interpret certain parameters and abnormalities in water quality Understand the critical control points in water quality management Decide what corrective action should be taken on certain operational or technical issues that control specific physical and chemical factors in water and relate it to a specific organism s water quality requirements Ensure that quality assurance systems related to water quality are in place and maintained Learning Outcomes At the end of this module you must be able to demonstrate a basic knowledge and understanding of: Names and functions of all the various components of water supply and quality systems. Attributes of water related to water quality. The requirements of organisms related to their water need. The purposes of maintaining relevant water quality for living organisms. Measurement and recording technique. Water purification techniques and systems. Relevant legislation related to the feeding and care of living organisms. Relevant legislation related to water use and environmental issues. Interpersonal skills related to communication. Sensory and documented cues related to water quality. Sensory cues related to the water requirements and use of water by living organisms. What do I need to know? It is assumed that the learner attempting this module can demonstrate competence against the unit standards listed below: NQF 2, , Monitor water quality NQF 2, , Operate and support a food safety and quality management system in the agricultural supply chain NQF 2, , Apply sustainable farming practices to conserve the ecological environment

7 7 Water Quality an Introduction The information below is a summary of the work you have been doing in Level 1 & 2. Please read through it carefully to refresh your mind. Understanding Water Quality Management Irrigation is used in crop production to supply plants with the water they need in addition to rainfall. Water quality factors that are important depend on the type of irrigation system used. Micro-sprayer irrigation is the most commonly used in South Africa to irrigate permanent crops and drip irrigation the second most common. Water dissolves many substances, such as salts, and is a carrier for a lot of suspended material, which influences the water quality, and which is why it is polluted to easily. Water quality management (WQM) has to do with managing foreign material in the water, and not with the water itself. Water quality management concerns six critical control points, being: Determining the quality of the water received on the farm; Identifying the causes of the said quality; Being aware of the quality standards of water for crop production; Improving the quality of received water where possible; Identifying water quality factors that cannot be improved and need to be managed; and Managing the quality of the water leaving the farm. Physical Water Quality Factors (PWQF) is determined by the foreign material that does not dissolve in the water. This type of material like silt can clog emitters and pipes. Chemical Water Quality Factors (CWQF) refer to the non-visible qualities of water, and affects crop production, the sustainability of the soil productivity and the effectiveness of the irrigation system. The Importance of Water Quality in Agriculture Water quality has direct and indirect effects on crop production and fruit quality. The direct effects of water quality include high salt content causing less water being available for the plant, a high concentration of magnesium interfering with the utilisation of potassium, high concentrations of nitrogen during January to June causing reduced fruit quality and yield, high water ph reducing the availability of nutrients, high chlorine levels in water used for foliar sprays causing scorching, and an oversupply of boron.

8 8 Indirect effects refer to factors that negatively impact on soil, the efficacy of foliar sprays, and that cause the blocking of emitters. Indirect effect of water quality include a high water sodium content gradually destroying the soil structure, the ph value of water used for foliar sprays negatively effecting the efficacy of the sprays and influencing the half-life of certain chemicals, and blocked emitters causing uneven and insufficient waterspread. It is easier and cheaper to control PWQF than CWQF for large volumes of water. PWQF can be improved through sedimentation and filtration. CWQF can be improved by correcting the ph (mostly for water used for foliar sprays) and oxidation, while certain CWQF can be compensated for by dealing with the SAR in the soil maintenance program, and dealing with chlorides by supplying trees with more calcium and supplying nitrogen as nitrates. The quality of water leaving the farm can be improved by preventing nitrogen leaching, controlling the application of chlorides, preventing water runoff, and preventing dumping. Water received on the farm, stored in dams and leaving the farm is regularly tested to determine its quality. A sample is not a piece of the whole, but the whole reduced to a manageable volume. Basic Water Quality Tests and Analyses For water samples, use new or used plastic bottles that have been washed properly with water. Tie labels to the neck or stick them on the outside. Take a water sample by filling the bottle and closing it without leaving an air bubble. ph tests and electrical conductivity (EC) tests are performed on a regular basis. ph test are done with the help of either a ph meter or ph sensitive paper strips EC testing is done with an EC meter. In both ph testing and EC testing a reference standard is used against which the sample is tested. Reporting on water tests involves ensuring the correctness of the standards, ensuring that the units are correct, and comparing the results from previous results of tests taken from the same source.

9 9 Maintaining Water Quality Control Systems A water quality control system (WQCS) involves the monitoring of water received on the farm and water leaving the farm. Maintaining a WQCS involves main water source or sources, effluents from rinsing the irrigation pipes, effluents from backwashing the filters, other signs of water contamination, and the composition of water leaving the farm. To maintain optimal PWQF, records must be kept of irrigation maintenance actions, such as the replacement of emitters, to assist with water quality management. To maintain optimal CWQF, acids to acidify the water, sterilising agents, and buffers to adjust the ph of water used for foliar sprays are required. Records are kept to set standards for particular water sources, and to monitor changes in the water source over time. Water that conforms to the water quality standards for crop production, and sources of good and moderate quality water is often mixed to achieve more acceptable quality. Historical water quality records are kept for the beginning and end of each rain season, and are used to detect historical trends. My Notes

10 10 Micro-Sprayers and drippers Salts Saline Ph Half-Life Micro-sprayers and drippers are devices developed to deliver small volumes of water over a limited area in order to improve the efficiency of water usage. Micro-sprayers and drippers are the emitters in the irrigation system. Salts not only refer to table salt (sodium chloride), but any compound of acids and bases, such as calcium sulphate, protassium nitrate, magnesium chloride, etc. In these salts, calcium, potassium and magnesium are bases, and the salts are formed when acids like sulphuric acid, nitric acid and/or hydrochloric acid are added. Water with a high salt concentration, also referred to as high total dissolved salts (TDS), is referred to as saline. ph indicates the acidity or alkalinity of any substance, in this case water, on a scale of 1 to 14. ph can range from 1 (extremely acidic) to 14 (extremely alkaline). A ph value of 7 is neutral. Plant sap has a ph of 5.8 and the ph of human blood is almost 7. Water with a low ph is referred to as acidic. Water with a high ph is with a referred to as alkaline. The half-life of a chemical is the time taken for it to lose half their strength, or the period of time that must elapse for an agro-chemical to lose half of its original toxicity. Reverse Osmosis A water treatment process whereby dissolved salts, such as sodium, chloride, calcium carbonate, and calcium sulphate may be separated from water by forcing the water through a semi-permeable membrane under high pressure. Distillation Deionisation Fertigation Electrical Conductivity (EC) Demineralised Water The purification of salt or brackish water by removing the dissolved salts though allowing the water to evaporate and then condensate against a smooth surface, such as glass, from where it is collected again. Removal of ions from water by exchange with other ions associated with fixed charges on a resin. Fertigation refers to the practice of applying fertilisers through the irrigation system. Drip irrigation systems are most suited to fertigation. The electrical conductivity of water refers to its ability to conduct an electrical current. The more salts dissolved in the water, the higher the ability to conduct current, hence an increase in the EC value. Demineralised water refers to water from which the dissolved salts (minerals) have been removed. Car battery water is for example demineralised. In chemical laboratories, all water that is used, even for washing the equipment, is demineralised.

11 11 Session 1 Interpreting parameters and abnormalities in water quality. After completing this session, you should be able to: SO 1: Read, record and interpret certain parameters and abnormalities in water quality 1.1 Introduction Water quality is determined by assessing three classes of attributes, being: Physical water quality factors Chemical water quality factors Biological water quality factors Biological attributes of a waterway can be important indicators of water quality. Biological attributes refer to: the number and types of organisms that inhabit a waterway. The poorer the quality of water the fewer the number and types of organisms that can live in it. When assessing water quality, it is also important to look at the quality of organisms that live in a waterway. Some species are more sensitive to chemical and physical changes in their habitat than other species. If species that tend to be sensitive to pollution are present in a waterway, then that waterway most likely has good water quality. Chemical attributes of a waterway can be important indicators of water quality. Chemical attributes of water can affect aesthetic qualities such as how water looks, smells, and tastes. Chemical attributes of water can also affect its toxicity and whether or not it is safe to use. Since the chemical quality of water is important to the health of humans as well as the plants and animals that live in and around streams, it is necessary to assess the chemical attributes of water.

12 12 Assessment of water quality by its chemistry includes measures of many elements and molecules dissolved or suspended in the water. Chemical measures can be used to directly detect pollutants such as lead or mercury. Chemical measures can also be used to detect imbalances within the ecosystem. Such imbalances may indicate the presence of certain pollutants. For example, elevated acidity levels may indicate the presence of acid mine drainage. Acid mine drainage (AMD) is generally a non-point-source water pollutant. It is the acidic water that drains out of above-ground or under-ground coal and metal mines. Acid mine drainage impacts stream and river ecosystems by increasing acidity, depleting oxygen, and releasing heavy metals such as aluminium (Al 3+ ), iron (Fe 3+ ), manganese (Mn 2+ ), and zinc (Zn 2+ ). Acid mine drainage can occur during mining operations or long after a mine has been abandoned. Commonly measured chemical parameters include: ph, alkalinity, hardness, nitrates, nitrites and ammonia, ortho- and total phosphates, and dissolved oxygen and biochemical oxygen demand. The presence of faecal coliform, a bacteria, is also determined using a chemical test. This microscopic organism is too small to detect during the biological assessment of macro-invertebrate populations. In addition, some "chemical" measurements actually indicate the physical presence of pollutants in water. These include measurements such as: conductivity and density. Measurements of these chemical parameters of water quality can be made one at a time using low-tech field titration. However, several of these parameters may be measured at once using high-tech equipment. Physical attributes of a waterway can be important indicators of water quality. The most basic physical attribute of a stream is the path along which it flows. Most streams are classified as "meandering" or S-shaped. Meandering streams have many bends. The bends are characterized by deep pools of cold water along the outside banks where faster-moving water scours the bank. Meandering streams also have

13 13 riffles along the straight stretches between pools. The riffles appear as humps in a longitudinal stream profile. The S-shaped path of meandering streams prevents water from moving too quickly and flooding downstream ecosystems. The deep, cold pools of water provide ideal habitat for many species of fish even when overall stream-flow is reduced. The riffles help to hold water upstream during times of low stream-flow. Also, turbulence in the riffles mixes oxygen into the water. Natural stream-channel patterns, with their bends, pools, and riffles, are essential to decrease flooding as well as providing a suitable habitat for certain aquatic plants and animals. For these reasons, it is important to assess the physical attributes of a stream when examining its water quality. Measurements of a stream's physical attributes are used to describe the structure of a sampling site. This allows for the comparison of the biota and chemistry of similarly-structured streams at different locations. Measurements of a stream's physical attributes can also serve as indicators of some forms of pollution. For example, changes in temperature may indicate the presence of certain effluents, while changes in stream width, depth, and velocity, turbidity, and rock size may indicate dredging in the area. Other commonly measured physical characteristics of a stream include: elevation and catchment area, stream order, forest canopy, and total solids. 1.2 Effects of Physical Water Quality Factors The majority of commercial orchards is irrigated with micro-sprayers or drippers. The physical water quality factors (PWQF) have an effect on the system, primarily in physically blocking the emitters used in micro-irrigation systems. Physical factors that cause clogging in drippers or micro-sprayers are: Inorganic materials such as clay, silt and sand; Organic debris such as remnants of plants, seeds, animals, and aquatic fauna and flora; Living aquatic plants and animals such as algae and snails; Plastic cuttings and other debris from the irrigation pipes and equipment; and Lubricant residues.

14 14 Soil Composition Clay. silt and sand are the basic components of soil. Clay particles are very small (less than 0.002mm or 2 micron) and have several exchange sites. Silt is in fact very fine sand (0.002mm to 0.050mm or 2 to 50 micron) and is inert material. Sand has a diameter of 0.050mm to 2.00mm or 50 to 200 micron. All these are grouped together under the terms suspended solids or insoluble suspended material. Guidelines issued by the Department of Water Affairs and Forestry (DWAF, 1996) rates the clogging hazard of water as follows: Rating Minor hazard Moderate hazard Severe hazard Suspended Solids per Litre Water (mg) less than 50mg 50mg to 100mg more than 100mg It is important to know the sources of inorganic suspended material, and to be able to recognise them. They are as follows: Clay, silt, sand and organic debris are part of the natural soil-plant system. Running water collect soil and organic particles on its way and the movement (velocity) of the water carries these materials to the storage dams. These particles settle at the bottom of the dam when the velocity of the water decreases. The settling rate depends on the size of the particles and the chemistry of the water. Clay particles are very small, with an average size of <2 micron, and will take much longer to settle than sand, with an average size of 50 to 200 micron. If sodium is abundant in the water, the settling rate of clay is reduced. Water from boreholes contains less organic debris but can have suspended clay particles. In storage dams, aquatic plants and animals produce living and dead material of variable sizes and states of decomposition. Borehole water has little aquatic activity but once pumped into a dam, the same problems occur. Plastic cuttings and other such debris is generated when installing or repairing the plastic pipes and fittings in the irrigation system. Lubricants are usually contaminants from the pumps in the irrigation system. The PWQF are important when irrigating crops because they reduce the efficiency of the irrigation systems. Where macro-irrigation (basin or flood irrigation) is practised, the PWQF influence the soil and the plant. Silt and seeds are the two PWQF that are of consequence in this case. When water containing silt is used, the silt settles and accumulates on the soil surface over time. Permanent crops that grow on the same site for many years and over time the accumulated silt may form a layer on top of the soil, with completely different chemical and physical properties from the soil below. This may

15 15 change patterns of root development and water penetration and eventually have a detrimental effect on production. Seeds in the water source are carried to the orchard where they germinate and grow. These weeds compete against the crop plant for water and nutrients, and must be removed and monitored constantly, adding to production costs. 1.3 Sample, Read and Record Factors Water sampling is done by the water quality manager or a designated person capable of taking the sample correctly. It is very important that sampling is done correctly, because many decisions and actions are based on the analytical results of the sample. If the sample does not represent the water source correctly, the wrong answers will lead to wrong decisions, with increasing cost implications. Sample A sample is a reduced but true reflection of the water source as a whole and is not a piece of the water source. To evaluate the PWQF properly, samples should be taken before and after the filtering process. The analyses of the PWQF of a water sample taken before filtering can be done on the farm. A simple method to determine the insoluble material in a water sample is as follows: Step Step 1 Action Put filter paper in a drying oven, set it at 100 C and dry the paper for 24 hours; Step 2 Record the mass of the dried filter paper (Mass A); Step 3 Step 4 Filter a known volume, e.g. 500ml, of the water sample through the dried filter paper. Ensure that no insoluble material is left in the sampling container; Put the filter paper with the insoluble material in a drying oven, set at 100 C and dry the paper and residue for 24 hours; Step 5 Record the mass of the dried filter paper plus residue (Mass B); Step 6 Step 7 Mass B minus Mass A gives the mass of insoluble material for the volume of water that was used; Compare the result with the hazard indication table in section 2 of this chapter.

16 16 To improve the accuracy of this method, use one or even two litres of water to pass through the filter paper, which will reduce the margin of error by providing a greater mass of insoluble material to measure. Note that although 100mg suspended in 1,000ml water is a low concentration, it is rated as Severely Hazardous. The residue is inspected to identify the various components. Living aquatic plants and animals, such as algae and snails, or organic debris, such as remnants of plants, seeds, animals, aquatic fauna and flora, are usually only of consequence with open water sources, such as dams and rivers. Borehole water seldom contains any of these. The magnitude of the presence of these components can be established, without further identification of the individual organisms. Plastic cuttings from the irrigation pipes and equipment, and lubricant residues are seldom related to the water source, but to activities around the irrigation system. Inorganic materials such as clay, silt and sand can be detected by rubbing the residue between the fingers. Sand has a gritty texture, while silt and clay has a slippery texture. To be of any practical value, results and observations should be recorded in a matrix of previous readings. Without historical data, the water quality manager can only conclude that the source poses a minor, moderate or severe hazard. It is not possible to tell whether the water quality is deteriorating, or whether the filtering system is operating effectively. Concentration of insoluble material (mg per litre) in water source BIG DAM and filter bank BLOCK A Date Before Filtration After Filtration 1 26/07/ /03/ /07/ /03/ Water samples should be taken at least twice per annum, before (March in this example) and after (July in this example) the rainy season. The comparisons between readings 1 and 3 or 2 and 4 gives the year on year variation and between readings 1 and 2 or 3 and 4 the seasonal variation of the intake water. The Before Filtration readings serve as indicators of the stability of the catchment area and upstream environment of the water supply. In this example, the readings show increases from 1 to 3 as well as from 2 to 4, which indicate that the concentration of insoluble material is increasing.

17 17 The After Filtration readings are a measurement of the efficiency of this filter bank. This is related to the number of drippers or micro-sprayers blocked, as well as to the insoluble material find when the lateral piping is flushed. A seemingly low concentration of insoluble material can accumulate in the piping. The negative effects of the WQF are usually cumulative and the final result is more than the sum of the individual factors. 1.4 Effects of Chemical Water Quality Factors Chemical water quality factors (CWQF) refer to invisible components of water. Instruments are required to measure the status of CWQF. These factors effect plant production, the sustainability of soil productivity, and the efficient operation of the irrigation system. The efficiency of an irrigation system is influenced by the degree of corrosion, deposits, or scale, in the pipelines, and blockages of the emitters. These three critical points are related to chemical water quality factors. The most important CWQF and their impact on each of these areas are shown in the table below, with the following classifications: Y = This factor has an impact Y/N = This factor may have an impact depending on other factors N = This factor seldom has an impact CWQF Crop Production Soil Productivity Irrigation System Efficiency Total soluble salts Y Y Y PH Y Y Y Calcium Y Y Y/N Magnesium Y Y/N N Sodium Y Y N Chloride Y Y/N N Bicarbonate Y Y/N N Boron Y Y/N N Iron, manganese and sulphides N N Y

18 18 Total Soluble Salts or Total Dissolved Salts (TDS) This is the most important of all the chemical water quality factors (CWQF), because the total dissolved salts (TDS) influences plant production, soil productivity, and irrigation system efficiency. The total concentration of salts dissolved in water is measured in terms of the electrical conductivity (EC) of the water or in milligrams per litre water. EC is expressed in milli-siemens per metre (msm -1 ). The quality of water in terms of electrical conductivity (EC) or the milligrams total dissolved salts (TDS) is expressed in many ways but most of these classifications are based on the system of US Department of Agriculture (USDA, 1954). The higher the salt content of the water the more energy a plant needs to utilise the water. This energy would have been better spent on producing vegetative material (leaves, shoots and roots) and fruit. Fruit trees irrigated with water containing moderately high concentrations of salts usually produce smaller fruit. When the salt content increases, the number of fruit produced by the tree declines. Compared to other crops, such as avocado, citrus can tolerate more salts in the water. In the table below, the salt tolerance of crops is expressed as the maximum salt concentration where the yield will be reduced by less than 10%. Crop Maximum EC (msm -1 ) Avocado 80 Citrus 135 Asparagus 400 Please note that the maximum EC at which a crop can still produce optimally also depends on other factors, such as the type of salts in the water, the type of irrigation system and the type of soil. The EC of the water can therefore only be seen as an indicator of the suitability of a water source for crop production. Another indicator of the maximum EC of water for crop production is the osmotic pressure. At an EC above 150mSm -1, energy is required to utilise the water and less energy is available for fruit production. At this EC, the osmotic potential of the water is at 50kPa which is also the maximum water tension permissible for optimum crop production. Remember that dissolved fertilisers add to the salt content of the water. Definition Osmosis Osmosis is the process when water moves from a low salt (or electrolyte) concentration to a high salt concentration if separated by a semi permeable membrane. If the concentration of salts is high in the water, water will move through the root membranes to the soil. To counteract this, the plant sends soluble organic components like sugars to the roots to increase the electrolyte concentration inside the root cells to create conditions where water will move into the root.

19 19 ph The salt content of water is also of importance with irrigation systems that wet the leaves. High concentrations of salts can scorch the leaves and cause them to drop prematurely. Water applied to the soil is either utilised by the plants or evaporates from the surface leaving salts behind in the soil. Because of irrigation, this process is repeated several times per month. The rate at which salts accumulate depends, amongst other factors, on the concentration of dissolved salts in the water. Apart from erosion, this is the single most important cause of the loss of productive soils. This process is called salinisation of soil, or verbrakking in Afrikaans. Total dissolved salts (TDS) is one of the factors contributing to the corrosive potential of water. The concentration and type of dissolved salts determine to what extent water contributes to the corrosion of irrigation equipment. Apart from erosion, the concentration and types of salts also determine to what degree water adds to the problem of scale forming and blockages of micro-sprayers and drippers. Three indexes are used to quantify the potential of water to corrode, form scale and block emitters, namely the Langelier, Rysnar and Aggressiveness Indexes. In this regard, the concentration of calcium, magnesium and carbonate are important. ph is a measurement of the level of acidity or alkalinity of water. A ph-value of 7 is neutral (neither acidic nor alkaline), while ph of less than 7 indicates acidity and greater that 7 alkalinity. Therefore, the lower the ph-value, the more acidic and the higher the value, the more alkaline is the water. The optimal ph of irrigation water is 6 to 6.5, i.e. slightly acidic. The ph of water is caused by the carbonates and bicarbonates, but there is no relation between the ph and the concentration of these two ions. The ph range for soils to achieve optimal production for most crops is between 6.5 to 7, as measured in a soil-water suspension. Water with a low ph will contribute a little to acidification of the soil, but water with a high salt content is a major reason for the salinisation of the soil. The ph of the water determines to a large extent the solubility of salts and hence the TSS of water. At a low ph, water dissolve metals in metal pipes and fittings, and salts in cement based piping. At a high ph, salts like calcium and magnesium carbonates precipitate.

20 20 Sodium The importance of sodium and its effect on soils are expressed as the sodium adsorption ratio (SAR) of water. This is the magnitude of the relation between sodium and calcium plus magnesium. A SAR-value of less than one indicates no hazard, between 1 and 3 a minor hazard, and higher than 3 a major sodium hazard. Sodium Absorption Ratio (SAR) The sodium adsorption ratio (SAR) is a measurement of the relation between sodium and calcium plus magnesium in the water as well as in an extract of the soil. The higher this value, the more sodium is present and the greater the hazard of degradation of the physical properties of the soil. Chloride Chloride (Cl) has several effects on crops. Chloride is an essential nutrient element, but a high concentration increases the osmotic pressure of the water and competes with other anions. Bicarbonates Dissolved bicarbonates (HCO 3 ) are responsible for the high ph of water. An alkaline ph has a negative effect on the solubility of certain plant nutrients. Boron Boron (B) is also an essential plant nutrient, but is required in very small amounts. If the water contains too much boron, phyto-toxicities develop. Iron, Manganese and Sulphide These three elements are responsible for the formation of insoluble oxides, sludge and filamentous gelatine-like slimes which block emitters. 1.5 Biological Processes Relating to Water Quality The oxygen demand of known biological processes in water has little influence on the quality of the water used for irrigation and foliar sprays in crop production. However, biological processes that influence the efficiency of the irrigation system include the activities of bacteria and fungi, which form slimes and filaments, and reduce manganese, iron and sulphur. The cumulative results of these activities may

21 21 cause other physical particles to accumulate in the irrigation system, which cause clogging of the emitters. Under anaerobic conditions, such as in boreholes, sulphates can be reduced by bacteria to form sulphuric acid. Sulphuric acid dissolves metals like steel pipes and brass valves in irrigation systems. The most outstanding symptom of this process is nodules containing black or dark brown powdery material. This process continues to create holes in the metal and will destroy it eventually. The presence of sulphate reducing bacteria (SRB) in boreholes thus has a negative effect on the underwater equipment. The poorer the quality of water the fewer the number and types of organisms that can live in it. Water is also a carrier of spores of diseases, such as Phytophthera, and even organisms like nematodes to the field or orchard. Please complete Activity 1 at the end of the session My Notes Concept (SO 1, AC 1-4) The effects of certain physical factors of water and relate and apply them to a relevant specie of animal or plant requiring water are demonstrated. The ability to sample, read and record factors accurately is demonstrated. An understanding of the effects of certain chemical factors is demonstrated. General knowledge of biological processes of animals and plants, which relate to specific physical and chemical quality factors in water are demonstrated. I understand this concept Questions that I still would like to ask

22 22 1 SO 2 Individual Exercise: Answer the questions below My Name: My Workplace: My ID Number: Describe a simple method to measure the suspended solids in irrigation water List the CWQF that have an impact on the following Soil Productivity Plant Production Irrigation System Efficiency Facilitator comments: Assessment:

23 23 Session 2 Critical Control Points in Water Quality Management After completing this session, you should be able to: SO 2: Demonstrate an understanding of critical control points in water quality management 2.1 Introduction Irrigation water is required in large volumes and the water quality manager (WQM) can usually only improve PWQF economically, while most CWQF cannot be improved economically. Although the biological water quality factors (BWQF) are of lesser importance, they should form part of the critical control points (CCP) in water quality management. The stated optimum ranges for CWQF for crop production is merely of academic importance and only alerts the WQM to take action to minimise the impact of CWQF on production. It is also important to take note of the long term effects of the CWQF on the soil and the environment. The extent to which the CWQF can be changed economically also depends on the irrigation system used, for instance with open hydroponics the ph of the water can more readily be changed than with microsprayers. The main task of a WQM for crop production is to know: The quality of the water on hand; The impact of the water quality on the crop, soil, equipment, and environment; How to improve the PWQF; and How to minimise the impact of sub-optimum CWQF on the plant, soil and equipment. The WQM does not only measure the quality factors of the water alone, but also identifies the points of impact on the crop, soil and equipment. The critical control points (CCP) are therefore be closely related to the filtration system (PWQF), the soil, crop and equipment (CWQF and BWQF). Critical Control Point: A critical control point (CCP) is an aspect of a system that has a major impact on the system and can be measured, controlled and monitored to ensure that the outcome will be acceptable.

24 Water Quality Requirements There are not many water quality requirements for crop production and the ranges for these parameters are very broad. As an example citrus is produced economically using water with TDS from very low to higher than 1500mg per litre and with a ph ranging from 4 to 9. In general crops do well with a ph in a region of 7. On the other hand, any water quality factor that has a detrimental effect on the soil, such as increasing salinity, or on the irrigation system, such as clogging or corrosion, will have an impact on crop production. The following tables 3.15 and 3.14 (as in the source document) give a general overview of water quality parameters for crop production: My Notes

25 25 Summary of water quality guidelines for irrigation Source: SA Water Quality Guidelines, Vol 4 Agricultural Use (DWAF)

26 26 In many cases, the WQM has little or no influence on the quality of the water received on the farm or has no alternative than to use the particular source. Therefore, the table above merely serves as a tool to underline which WQF need attention. Some of these quality factors can be treated economically to improve the quality of the water while others cannot and measures need to be put in place to minimise the effect on the soil, the irrigation system and hence crop production. The impact of the quality factor needs to be measured and monitored at the earliest stage of development. It is senseless to wait until the impact of a particular factor is measurable in the crop before corrective actions are taken. It is more cost-efficient to anticipate the impact and correct it as early as possible. Some of the negative results will have a slow and initially mostly unnoticed impact on the crop until such time that it can only be corrected at a huge cost, if at all.

27 Critical Control Points for Water Quality Measurements Impact on Crop Production Usually the crop will be the last to respond to the impact of poor WQF and should not be regarded as an indicator of the water quality. The influence of water quality factors on production can be seen in suboptimal yields, decreasing fruit size, erratic blossom and decrease in the number of fruit. Many other production factors can however be the cause of these problems. Impact on Sustainable Soil Productivity Soil analyses are a cheap and effective method to monitor the effects of water quality factors. The most important CCP that can be measured by soil analyses are the following: Salinity Salinity can be detected by the ph, resistance or electrical conductivity (EC), as well as sodium and chloride content of the soil. An increase in ph, EC and/or sodium and chloride content is the first signs of salinisation. In order to detect changes in the concentration of these parameters, all results must be recorded. Recordkeeping is the fundamental requirement for any water quality management system. When the concentration of sodium exceeds 5% of the total cations, salinity becomes a real threat and additional analyses are required. Additional analyses include the sodium adsorption ratio (SAR) and electrical conductivity (EC) of the saturated soil paste. Soil paste is a soil sample saturated with distilled water. Crusting Crusting is a phenomenon that develops in the top few millimetres of the soil when it forms a hard layer. This is caused by a decrease in the relative concentration of calcium as a result of irrigation with too fresh water, i.e. water with a very low concentration of salts, or water containing too much sodium. The first sign of crusting is runoff of water halfway through the irrigation cycle. Runoff occurs when the application rate exceeds the infiltration rate of water into the soil, which is reduced by crusting. Initially the infiltration rate exceeds the application rate and the water will disappear quickly. After a while, the top layer closes, reducing the infiltration rate, and water accumulates on the surface. More water evaporates from the surface and less water than intended reaches the roots. Although the correct volume was applied, the crops received too little water.

28 28 Leaching Depending on the concentration of salts in the water, the leaching requirement of a crop-soil-water system is important. Leaching Requirement The leaching requirement (LR) is the extra volume of water required, over and above what is needed to rewet the soil to field water capacity, to leach salts left from the previous irrigation from the root-zone. By incorporating the LR into the water requirement, the salt content will not increase in the soil. The LR is a factor of the crop and the EC of the water. Impact on the Irrigation System The most important CCP of an irrigation system is the delivery rate of the emitters. The delivery rate is an effective CCP because it measures the influence of many factors on the effective application of water. The effective application of water promotes optimal yields and fruit quality. When the irrigation system is operating at working pressure, the delivery rate of all the emitters must be within preset limits. Blockages decrease the delivery rate to less than specified. Delivery rate is measured as millilitres water passed through an emitter in one hour. This varies depending on the type and size of the emitter. The delivery rate with its permissible tolerance is specified for every commercial emitter on the market. Specifications for Two Commercial Micro-Sprayers Combination Pressure (m) Delivery Rate (litres / h) Radius (m) 0.82mm nozzle with orange spreader 1.28mm nozzle with green spreader The acceptable deviation from the specified delivery rate is <10% (ARC, 2003). This means that the delivery rate for the 0.82mm nozzle with orange spreader should be between 22.5 and 27.5 litres per hour at an operating pressure of 10m.

29 29 The following procedure is followed to measure the delivery rate of emitters: Micro-Sprayers Procedure Step 1 Step 2 Step 3 Remove the micro-sprayer and put a riser tube in a suitable container to collect the water; Let the water run into this container for a set period, for instance 60 seconds; Measure the volume of water emitted in 60 seconds, for instance 500ml Calculate the litres emitted per hour, as follows: Step 4 Volume Collected x 3,600 / number of seconds measured = 500 x 3,600 / 60 = 30,000ml = 30 litres per hour Step 5 Compare this with the specified delivery rate for the particular microsprayer Drippers Procedure Step 1 Step 2 Step 3 Place a suitable container below the dripper to collect the water. Ensure that the water does not run away from the container against the pipe. The dripper must be the lowest point and over the container; Let the water drip into this container for a set period, for instance 30 minutes; Measure the volume of water emitted in the 10 minutes, for instance 750ml; Calculate the litres emitted per hour, as follows: Step 4 Step 5 Volume collected x 60 / number of minutes measured = 750 x 60 / 30 = 1,500ml = 1.5 litres per hour Compare this with the specified delivery rate for the particular dripper

30 30 This exercise forms part of the irrigation management system. The delivery rate of micro-sprayers can also be checked by the size of the wetted area. When blocked partially, the radius of the wetted area will be reduced. However, as illustrated in the above table, the wetted radius is not a very sensitive measurement of the delivery rate. In water quality system management, prevention is indeed better than cure. Removing blockages from drippers or micro-sprayers is costly and seldom successful. Systems must be in place to prevent blockages. Please complete Activity 2 at the end of the session My Notes Concept (SO 2, AC 1-4) I understand this concept Questions that I still would like to ask An understanding of the water quality requirements and acceptable ranges of a relevant animal or plant species is demonstrated. The ability to make comparisons and to explain and interpret recorded readings of water quality measurements is demonstrated. An ability to explain the physical, chemical and biological requirements and recall acceptable physical and chemical ranges of a relevant animal or plant species is demonstrated.

31 31 2 SO 2 Group Activity: Divide into groups and decide My Name: My Workplace: My ID Number: 1. Why is delivery rate of a micro jet or dripper an important critical control point? 2. Calculate the delivery rate of a micro-jet from the data supplied and comment on the result: Specified Delivery Rate: 65 litres per hour Volume of Water Measured in 60 seconds: 855 millilitres Facilitator comments: Assessment:

32 32 Session 3 Water Quality Management Systems After completing this session, you should be able to: SO 3: Enable corrective action to occur on certain operational or technical issues that control specific physical and chemical factors in water and relate it to specific organism s water quality requirement 3.1 Water Quality Management Systems (WQMS) The worst experience with any quality control system is if a crop failure is due to a foreseeable and correctable quality factor. A reduction in total yield and/or fruit size has a direct effect on the profitability of the farm, as the input costs have been incurred, but the part of the crop that should generate the profit is lost. WQMS are interlinked with the irrigation system and maintaining the irrigation system includes the maintenance of WQMS. The even distribution of water throughout the orchard is in the first place dependent on the quality of the irrigation system. However, once installed and functioning properly, the maintenance of even distribution of water also depends on effectiveness of the WQMS. Apart from the quality of the water received for irrigation, the introduction of other chemicals like fertilisers (fertigation), cleaning aids and pesticides (chemigation) also dictate the scope and magnitude of the WQMS. Chemigation Chemigation is the process whereby water-soluble chemicals, such as fertilisers, pesticides, cleaning agents and even herbicides, are applied through the irrigation system.

33 33 WQMS Requirements Water with EC of 50mSm -1, SAR of <1.00 and total suspended solids of <50mg per litre requires a less intensive WQMS than water with EC of 125mSm -1, SAR of >3.00 and 100mg suspended solids per litre. The development of any WQMS must be based on the quality of the water received for irrigation, with consideration given to whether fertigation and chemigation are practised. When chemicals are added to the water, the EC increases, chemical reactions can result in the formation of precipitates, and the ph and microbial activities might be affected. These reactions require a re-evaluation of the WQMS and specifically the critical control points. 3.2 Adjusting and Maintaining Water Quality Management Systems Setting up a WQMS requires less effort than maintaining it. A WQMS is maintained over an extended period (months and years) and tends to receive less attention once other activities require attention. Maintaining a quality control system is to ensure that: Measurements are done in time; Measurements are recorded in the correct format; Results are reviewed according to the set intervals; Appropriate actions are taken to maintain quality; and Outcomes of actions are monitored. The water quality manager should have a fixed schedule for measuring, recording, reporting and reviewing results. This schedule should include the most important critical control points and should not be cluttered by unnecessary measurements and information. To fulfil this function, the water quality manager requires: A proper knowledge of all water quality factors; The impact of WQF on the irrigation system, the soil and the crop production; and The impact of fertigation and chemigation on the WQF.

34 34 Maintaining the WQMS requires updated information on new cleaning chemicals, fertilisers and aids to handle WQF. The quality of the water however in the end determines the level of control required. When the quality of the water is good and the seasonal fluctuations small, WQM will have a low profile. 3.3 Recording and Reporting An effective WQMS is a simple system that focuses only on those factors that have a negative impact on crop production. These include factors that: Clog emitters; Reduce water penetration into the soil; Has a negative impact on the productivity of the soil; Reduce the efficiency of foliar sprays; Reduce the production of quality fruit; and Pollute the water leaving the farm. Of these six impact areas, clogging is the single most important, because clogging can be prevented at a relatively low cost. Preventing clogging at the source also improves the quality of the irrigation and reduces the maintenance cost of the irrigation system. The challenges faced are as follows: Deciding which of the water quality factors and the additions to the water (fertigation and chemigation) will have an impact on the production of quality fruit; Measuring the impact; and Putting counter measures in place to reduce the negative impact. Please complete Activity 3 at the end of this session My Notes

35 35 Concept (SO 3, AC 1-3) An understanding of the working of water quality management systems is demonstrated. The ability to adjust and maintain water quality management systems and equipment is demonstrated The ability to record and communicating findings on the maintenance of water quality and water quality management systems is demonstrated I understand this concept Questions that I still would like to ask My Notes

36 36 3 SO 3 Group Activity: Divide into groups and decide My Name: My Workplace: My ID Number: 1. Why is clogging of emitters the most important WQM factor? 2. Why is measuring emitter delivery rate so useful? 3. Name at least four CCP that need to form part of the WQMS for crop production. Facilitator comments: Assessment:

37 37 Session 4 Concept of Quality Management Systems After completing this session, you should be able to: SO 4: Ensure that quality assurance systems related to water quality are in place and maintained 4.1 Concept of Quality Management Systems (WQMS) In short, the WQMS is a set of checks to: Evaluate the quality of the water received on the farm: Which WQF are suboptimal? Which WQF can be improved? What precautions are required? Evaluate the seasonal variation in water quality. To what extent do fluctuations influence the requirements for the WQMS? Develop systems to improve the quality where possible: Filtration is required for almost all water. Is a pre-filtration process like a settling dam required to remove excessive suspended solids? Set up systems to minimize the impact of those WQF that cannot be improved economically. How do I deal with a high sodium concentration in the water? What is the leaching requirement? Do I need to acidify the water used for foliar sprays? Monitor water quality. How do I know that the filtration is adequate? How can I measure the performance of the filtration process?

38 38 Develop a system to record the analytical data required to monitor the level of sodium and salts in the soil. Evaluate and monitor the quality of the water leaving the farm. Where do I sample the out-going water? 4.2 Importance of Quality Management Systems The importance of water quality management is dictated by the quality of the irrigation water received on the farm. The poorer the quality, the more important a good, reliable water quality management system is. The effectiveness of the water quality management impacts directly on the profitability of a commercial orchard or field. Irrigation has a direct influence on the yield and fruit quality produced by the crop. Optimal irrigation can only be achieved if the crop receives the correct volume of water. The correct volume of water can only be delivered to the individual plants if all emitters are functioning correctly. Sustainable profits are only possible if the soil is kept in an optimal chemical and physical condition. The physical, chemical and biological water quality factors of irrigation water determine to a large extend the success of a commercial orchard or field. The aim of water quality management is therefore to ensure that the maximum profit is achieved under the set conditions. 4.3 Improvements to Quality Management Systems Improvements in the WQMS are on two fronts, being the administration of the system and the incorporation of new technology to improve quality and measurements. Two WQMS are seldom the same and the administration thereof depends on the facilities available and the people involved. This leaves room for continual improvement with the focus on simplicity and efficiency. However, any WQMS must be able to report and manage all those WQF that will impact on production of quality fruit.

39 39 Why water quality is important on a Farm. What kinds of parameters and abnormalities might exist in Water Quality on a farm? Use the table below as a template or a checklist to use in your own circumstances. The checklist gives an indication of the factors that you need to consider when making decisions on the improvement of water quality. Factor Physical factors Temperature Chemical factors (dissolved gasses) ph What impact it might have on water quality Water without any physical foreign components is preferable but by screening and filtering a degree of physical material can successfully be removed. Cost will determine the feasibility of such an operation. High temperatures will increase the growth of biological contaminants. Most plants has the ability to withstand a degree of chemical contamination but an over exposure may stun growth or kill the crop Probably the most important factor determining water quality How to interpret whether it is normal or abnormal for crop production Most crops are not negatively influenced by foreign material but the irrigation system is badly affected Strive to keep the temperature of the water as cool as possible Different crops will react differently to different chemical compounds. A ph level of 7 o7 is or slightly below is preferable to most crops

40 40 When ascertaining the quality of water certain adjustments must be made by the producer in order to rectify any deficiencies that might affect the quality of the product produced. The list below includes the major factors that must be considered when assessing the suitability of the water to be used. The Effects Of Certain Chemical Factors On Water Quality For An Irrigation Farm. The effects of certain other types of animals and plants, which might affect the specific physical and chemical quality factors in water on an irrigation farm e.g. If there are also sheep found on your farm and they are grazing on the banks of the river, how it might influence the irrigation water used for your crops. The Critical Control Points in Water Quality Management for a Farm The water quality requirements and acceptable ranges for crop production Factor Physical factors Temperature Chemical factors (dissolved gasses) ph Biological processes photosynthesis Biological processes - nitrogen cycle Biological processes decomposition Organic load Is this an important factor to consider when assessing water quality for crops? Yes Yes Yes yes Yes Yes Yes Yes What is the acceptable reading or recorded value for optimum crop production? Will differ according to the specific crop Will differ according to the specific crop Will differ according to the specific crop Will differ according to the specific crop Will differ according to the specific crop Will differ according to the specific crop Will differ according to the specific crop Will differ according to the specific crop A practical example (with practical readings and recorded data) of water quality reading that is normal for an irrigation farm: A practical example (with practical readings and recorded data) of water quality reading that is abnormal for an irrigation farm:

41 41 How we can decide what corrective action should be taken on certain operational or technical issues that control specific physical and chemical factors in water and relate it to a specific organism s water quality requirements What to do if crops show Nitrogen deficiencies: What to do if crops show Phosphorus deficiencies: What to do if crops show Magnesium deficiencies: Apply fertilizer with a high ratio of nitrogen relative to P and K e.g. 7 : 1 :3 Add fertilizer like 2: 3 : 2 To rectify a trace element deficiency it is advisable to do a thorough soil analyses as certain factors might only be causing a slow absorption rate of these trace elements Please complete Activity 4 at the end of the session My Notes Concept (SO 4, AC 1-4) The concept of quality management systems is explained. I understand this concept Questions that I still would like to ask Quality management systems include but are not limited to systems such as GAP, TQM, and QES Quality management systems with regarding to the supply of water to living plant and animal organisms is explained. Improvements regarding water supply and quality systems is recommended.

42 42 4 SO 4 Group Activity: Divide into groups and decide Make notes of the discussions My Name: My Workplace: My ID Number: 1. What is the basic principle of taking a water sample? 2. Describe the procedure of taking a water sample from a dam. 3. Describe in short what needs to be checked in a general WQMS.

43 43 4. Obtain a copy of a quality control framework: either Eurepgap, BRC, or HACCP. Describe how you will use this to maintain the water quality system on your farm. Facilitator comments: Assessment:

44 44 Am I ready for my test? Check your plan carefully to make sure that you prepare in good time. You have to be found competent by a qualified assessor to be declared competent. Inform the assessor if you have any special needs or requirements before the agreed date for the test to be completed. You might, for example, require an interpreter to translate the questions to your mother tongue, or you might need to take this test orally. Use this worksheet to help you prepare for the test. These are examples of possible questions that might appear in the test. All the information you need was taught in the classroom and can be found in the learner guide that you received. 1. I am sure of this and understand it well 2. I am unsure of this and need to ask the Facilitator or Assessor to explain what it means Questions I am sure I am unsure Summative Multi-media Learner Presentation Instructions to the learner: A person assessed as competent against this standard will be able to: 1. Read, record and interpret certain parameters and abnormalities in water quality 2. Understand the critical control points in water quality management 3. Decide what corrective action should be taken on certain operational or technical issues that control specific physical and chemical factors in water and relate it to a specific organism s water quality requirements 4. Ensure that quality assurance systems related to water quality are in place and maintained Accordingly you have to prepare a presentation for the assessor and the class around these four points listed above, as applicable to the farming situation. The presentation should be: a multi-media based one, using the posters supplied in this workbook as a resource. No longer than 15 minutes in duration Should be planned according to the guidelines listed below, and should include information on ALL the points.

45 45 The evidence required by the assessor will be obtained from the following sources: 60% Written information as completed in the planning notes of this workbook 30% Oral communication from multimedia presentation 10% Correct interpretation and applied use during presentation of the given resource posters and pictures. My Notes

46 46 Checklist for practical assessment Use the checklist below to help you prepare for the part of the practical assessment when you are observed on the attitudes and attributes that you need to have to be found competent for this learning module. Observations Can you identify problems and deficiencies correctly? Are you able to work well in a team? Do you work in an organised and systematic way while performing all tasks and tests? Are you able to collect the correct and appropriate information and / or samples as per the instructions and procedures that you were taught? Are you able to communicate your knowledge orally and in writing, in such a way that you show what knowledge you have gained? Can you base your tasks and answers on scientific knowledge that you have learnt? Are you able to show and perform the tasks required correctly? Are you able to link the knowledge, skills and attitudes that you have learnt in this module of learning to specific duties in your job or in the community where you live? Answer Yes or No Motivate your Answer (Give examples, reasons, etc.) The assessor will complete a checklist that gives details of the points that are checked and assessed by the assessor. The assessor will write commentary and feedback on that checklist. They will discuss all commentary and feedback with you. You will be asked to give your own feedback and to sign this document. It will be placed together with this completed guide in a file as part of you portfolio of evidence. The assessor will give you feedback on the test and guide you if there are areas in which you still need further development.

47 47 Paperwork to be done Please assist the assessor by filling in this form and then sign as instructed. Unit Standard Learner Information Form Program Date(s) Assessment Date(s) Surname First Name Learner ID / SETA Registration Number Job / Role Title Home Language Gender: Male: Female: Race: African: Coloured: Indian/Asian: White: Employment: Permanent: Non-permanent: Disabled Yes: No: Date of Birth ID Number Contact Telephone Numbers Address Postal Address Signature:

48 48 Bibliography Books: ARC: Mikrobesproeiingstelsels,, 2003, Hfst 8 van die Besproeiingsbedryfshandleiding, ARC Institute for Agricultural Engineering DWAF: South African Water Quality Guidelines, 1996, Vol. 4, Department of Water Affairs and Forestry, Pretoria USDA, Saline and Alkaline Soils, 1954, Booklet 60 Terms & Conditions This material was developed with public funding and for that reason this material is available at no charge from the AgriSETA website ( Users are free to produce and adapt this material to the maximum benefit of the learner. No user is allowed to sell this material whatsoever.

49 49 Acknowledgements Project Management: M H Chalken Consulting IMPETUS Consulting and Skills Development Donors: Citrus Academy Boland College Authenticator: Rural Integrated Engineering Technical Editing: Mr R H Meinhardt Mr. C Klindt OBE Formatting: Ms B Enslin Design: Didacsa Design SA (Pty) Ltd Layout: Ms SA Bredenkamp Ms N Matloa