Learn to understand and better manage soil and water chemistry
- avoid serious problems with soil or water contamination
- manage the quality of drinking water for people and animals
- manage water quality in the environment - from rivers and lakes to swimming pools
- identify and manage soil contamination through to soil deficiencies
Course Content
There are eleven lessons in this course as follows:
- Soil Chemistry – Introduction
- Soil Chemical properties and processes
- Soil -chemical testing
- Soil chemistry- applications in agriculture
- Soil chemistry – applications in environmental management
- Water chemistry –Introduction
- Water - chemistry of water sources and drinking water
- Water – chemical testing
- Water chemistry –applications in agriculture
- Water chemistry – applications in the environment management
- Temperature effects of water and general health
Course Duration - 100 hours of self paced study
Learn How Soil & Water Chemistry Matters.
In todays increasingly polluted world, it is very important to know the chemical nature of a soil or water before you use it.
If you want to be certain that a catastrophe does not occur, it is wise for the source of water to be tested for quality before setting up a farm or garden.
Testing Water
It is relatively easy to obtain and and test water before setting up any venture. Since a number of water quality parameters can effect the composition of the nutrient solution and play a role in factors such as pH management, water testing is a vital component of testing. A water analysis or report is always the best place to start if water quality issues are suspected – municipal water suppliers should be able to provide customers with a full water report which includes mineral analysis as well as water treatment chemicals such as chlorine or others. For those using other water supplies such as ground or well water, river or dam collected water, obtaining a water analysis is relatively easy and all that is required is to send a sample off to an analytical or agricultural testing lab. Water reports, while extremely useful, may not cover all potential problems, however they usually give a fairly good indication of where any issues lie with a water supply.
Water samples for testing should be collected in a clean, well rinsed bottle and sent immediately to the lab. Parameters to be analysed for vary slightly between labs, however the following are usually included in a basic `irrigation water test’:
pH, EC, calcium, magnesium, potassium, sodium, ammonium, nitrate, chloride, sulphate, phosphate, iron, manganese, zinc, copper, boron, molybdate, carbonates (CO3), bicarbonates (HCO3), alkalinity (CaCO3).
Most water testing reports supplied by analytical labs will use units of either ppm (parts per million), mg/l (milligrams per litre) or mEq (milliequivalents).
Hydroponic Production Example:
For a hydroponic crop some reports may give a guide to the `desired level’ however these are generally not useful for hydroponic growers and refer to the use for potable (drinkable) water or water to be irrigated onto soil grown crops.
Minerals
Interpretation of a water quality test from the lab can be somewhat confusing and may require the assistance of a consultant depending on the results and how these may affect the nutrient solution and plant growth. The first quality parameter to consider is the mineral levels shown on the water test report. Some naturally occurring minerals, commonly found in most water supplies such as calcium and magnesium and low levels of trace elements such as copper, boron or zinc are plant usable elements which help reduce fertiliser requirements if present in high enough levels. These however should be adjusted for in the hydroponic nutrient formulation so that imbalances in nutrient ratios don’t occur over time, particularly in recirculating systems from the presence of extra elements in the water supply. Hydroponic nutrient formulations made up from the individual fertiliser salts are easily adjusted for the presence of calcium or magnesium in the water supply and the amount of calcium nitrate or magnesium sulphate reduced accordingly. This can also be carried out for small amounts of trace elements. However if trace elements in the water are higher than those required by the crop, then build up and toxicity may become an issue over time and the water may need treatment to remove these. Premixed nutrient produces can generally not be adjusted for the presence of minerals in the water supply, however some manufacturers do produce `hard and soft water’ nutrient products which can help adjust for some aspects of the water supply.
`Hard’ water and high alkalinity
On water analysis reports these are measured as alkalinity (CaCO3) and bicarbonates (HCO3) in units of ppm or mg/l. This is probably the most common water quality issue dealt with by hydroponic growers worldwide, even those on treated city water. Ground water may be `hard’ as can river, dam and city water supplies, although rain water in unpolluted areas is usually considered low mineral or `soft’. Municipal water supplies range from very hard to soft, depending on where the individual city water supply is taken from. Hard water has a high mineral content, usually originating from magnesium, calcium carbonate, bicarbonate or calcium sulphate which can cause hard, white lime scale to build up on surfaces and growing equipment.
Organic material and pathogens in water supplies
General purpose water quality tests from the lab tend to measure only minerals, pH and EC of the water supply and not other potential issues such as organic loading, plant or human pathogens which also affect hydroponic production. Separate lab testing can be carried out on water supplies to determine the presence of certain pathogens where these are suspected to be an issue. Generally city water supplies are filtered to remove any organic matter and treated to kill any microbial life which would include human and plant pathogens. However other water sources including well water, river, dam and rain water can harbour both organic matter and potentially damaging plant pathogen spores. In reality many large commercial hydroponic operations use untreated water sources with few problems, however in some areas pathogen contamination can be an issue. Zoosporic pathogenic fungi such as Pythium and bacteria can survive and be distributed in water, however these can be relatively easily cleaned up by the grower before use. The safest options are UV, ozone and slow sand filtration as these won’t leave chemical residues which may harm young, sensitive root systems. Small UV treatment and filtration systems such as those used in fish ponds and aquariums are suitable for treating water for hydroponic use and will kill plant pathogens and algae. However these are best used for treating water only, not nutrient solutions as UV can make some nutrients unavailable for plant uptake.
