Fischer EcoWorks
Water Management Issues and Tools
Click on subject to select
1. What is Water Management?
2. Water Sources
3. Water Demands
4. Water Distribution
5. Water Quality
6. Water Treatment
7. Fertigation
8. Irrigation
9. Water Collection
10.Recirculation, Disinfection and Re-use
11.Water Systems Integration
1. What is Water Management?
Water is a key element in all growing enterprises. If you are a grower, you probably have over the years developed an impressive patchwork of water systems and solutions. It might be time to sit back and have a good look at that whole water scene from source to nozzle to ditch.
Water Management means integrating the parts, addressing bottlenecks, and continuously matching your water resources with your irrigation needs. Smart water management will bring you considerable savings, improved plant quality, lower risk of disease, happier employees and reduced environmental impact.
The diagram below is an actual example of managing run-off from rain and irrigation, with the aim to reduce erosion, creek contamination, and supplying additional irrigation water.
Check with EcoWorks about how to put together all the pieces of
the puzzle before you invest.
2. Water Sources
Besides
the obvious issue of having enough water of acceptable quality available,
it is important to look at the reliability of the supply, and the projected
needs for the future. Adequate back-up sources will take the sting out
of emergency situations. Pond water easily gets contaminated, wells
often diminish in output over time, and city water can become too expensive.
Check with EcoWorks about –
- Collecting and storing rain water from greenhouse roofs. Would it make economic sense? Rain water is generally clean, low in minerals and can be valuable for blending with higher EC water.
- Deciding which combination of water sources will provide the most economical and safe supply. Does it make more sense to drill that new well, or to disinfect the water from the pond?
3. Water Demand
The water demands of your operation are as unique and
varied as your crop mix, irrigation systems and growing techniques.
System limitations usually show up in peak demand times, such as unexpectedly
hot days, or when in addition to regular watering many crops need to
be watered in time before shipping.
Check with EcoWorks about-
- Smart ways to spread out watering needs in order to reduce supply bottlenecks. Find out how far good water management can go, and when it is time to beef up your systems.
- Stretching your water supply by using different sources for different crops. Your plugs may need super-clean city water, while other crops do perfectly well with treated pond water.
- Creating buffer storage if your peak water demand exceeds source capacity. Tanks can be filled 24 hours a day, reducing demand on supply systems substantially. City water hook-ups often cost less with smaller pipe sizes/peak flow rates.
4. Water Distribution
Few
water supply and irrigation systems are the product of a master plan.
They grow with the operation, usually incorporating a variety of irrigation
technologies. Pipes are often a convoluted patchwork; systems are prone
to pressure fluctuations, brakes, scaling and biofilm. Various users
in connected systems often compete for water, compromising crops and
frustrating growers.
Check with EcoWorks about-
- Correctly sizing and routing pipes to minimize pressure losses and pumping power.
- Variable frequency drive pumps that help maintain constant system pressure at reasonable installation costs. They also eliminate the need for large pressure tanks.
- Adjustments in the pipe network to alleviate bottlenecks, water-hammer, and pump wear from cavitation.
- Systematic evaluation and overhaul of the existing water distribution system, especially when more growing area is added. Running a new main supply line can solve many problems, while secondary lines can be left alone.
5. Water Quality
We
all know the mantra that good water quality is essential for healthy
plants. However, it is easy to overlook important aspects that make
up water quality: pH and alkalinity, EC and fertilizer content, low
pathogen counts, no algae/bofilm and orifice-clogging solids, suitable
temperature.
Check with EcoWorks about:
- Assessing water quality needs for the crops you grow.
- Testing all water supplies. Set up test program for sources that can fluctuate seasonally, such as ponds. Find out whether city water is consistent. Some networks switch supplies occasionally or seasonally.
- Separating higher and lower quality users if high quality water is expensive.
Download Article “Facts
and Myths about Irrigation Water”
By Dr. Mirat D. Gurol
6. Water Treatment
Water
may need treatment before irrigation, during re-circulation, or before
discharge. Treatment can include removal of solids, organic matter,
excess trace minerals, dissolved salts, pathogens, eliminating algae
and biofilm, and more. pH and alkalinity may need adjustment, and nutrients
are commonly added.
Water treatment is complex business and often confusing. You find everything on the market from miracle cure-all’s to excellently engineered systems. Before you invest, get advice from people who do not just sell a particular product.
Check
with EcoWorks about:
Identifying clearly where, what for and to what extent you need to treat water.
Customized water treatment. Off-the-shelf treatment solutions are rarely satisfactory or cost-effective in the long run. Initial water quality and quality requirements vary greatly in different situations. Tailored solutions do not have to be complex or expensive, but they are more likely to do what they promise.
The economy of water treatment. You may be surprised how quickly it can pay off by savings on fresh water and fertilizer. While improved plant quality and reduced diseases are not always easy to quantify, they add to the benefits. Government grants and cost share programs can make re-use of water very attractive.
Download chart “Summary of
Water Treatment Options for Waterborne Pathogens”
by Wick, Konjoian, Fischer, Fisher and Argo
Download Slide Show “Selected Treatment Options for Waterborne
Pathogens” COMING SOON
by Ratus Fischer, ofa short course 2005
Download chart “Water Sources
and Related Treatment in Horticulture”
by Ratus Fischer, 2005
7. Fertigation
Adding
fertilizer to irrigation water can be as simple as an inexpensive in-line
proportioner, or as sophisticated as a computer controlled system mixing
individual nutrients on demand. The horticultural supply market caters
to almost any need.
Check with EcoWorks about:
- A close look at all your fertigation needs to decide if you are better off with decentralized mixing stations, or a centralized system that allow better control and safe handling of fertilizers.
- Minimizing human error by automating according to your need and preferences.
- Regularly checking and calibrating your equipment
8. Irrigation
For many
growers, watering is still where most labor can be saved per Dollar
invested. Most operations combine several types of watering systems,
such as sprinklers, drip, booms, flood benches or floors.
Download Chart "Selecting the Most
Suitable Watering Systems"
by Ratus Fischer
Check with EcoWorks about:
- Advantages and disadvantages of different irrigation systems
- Benefits and Risks of sub-irrigation
- Irrigation systems demands on supply water quality and pressure
9. Collecting Run-off
As
a grower, you likely deal with three main sources of run-off water:
1. Rain and snow-melt from roofs: High flows during storms.
Can be collected and used for irrigation with little treatment
2. Irrigation run-off: Small to medium amounts.
Loaded with fertilizer and possibly pathogens. Re-use requires treatment.
Discharge may be restricted.
3. Site run-off: High peak flows during storms may cause erosion and
discharge liabilities. Silt can make storage and re-use problematic.
Key to economical handling and use of run-off water: Separate water
from roof, irrigation and site as much as possible. This is usually
easy to achieve in new facilities, and sometimes challenging in established
ones.
Check with EcoWorks about:
- Using rain water for irrigation. Low EC makes it ideal for blending with high EC water from other sources
- Collecting rain water, reducing peak flows of storm run-off, preventing downstream erosion and other problems.
- Re-use of Irrigation run-off. If not mixed with high volume run-off from other sources, it can be treated economically at slow flow rates, saving on fertilizer, and alleviating pollution issues . Or it can be applied to treatment wetlands or open fields, preventing problems with point source pollution.
- Using closed sub-irrigation systems (Flood Flors, Flod Benches,
Gutters) to eliminate run-off completely, while providing economical,
high-quality irrigation for a wide variety of crops.
10. Recirculation, Disinfection and Re-use
The term Recirculation is mostly used in connection with Flood Floor, Flood Bench and Gutter irrigation systems. These are inherently re-circulating. Wasting 90% of the supply water is simply not an option.
Re-using water applies to any situation where irrigation water, often run-off from overhead irrigation, is collected and used again. Re-use can be in the same application again, or in a different one, such as field irrigation.
Disinfection,
Sanitation, Water treatment are terms used to describe elimination
or reduction of plant pathogens from the water. Total elimination is
rarely needed or achieved with reasonable cost. Reduction to safely
below symptom threshold is the goal.
Reduction in pathogen counts is expressed in “log”. One log means a tenfold reduction, 3 log a 1,000 fold reduction, etc. 3 or 4 log are common specifications for horticultural applications.
For more in depth discussion of water treatment, please click on the article links below.
- Inherently recirculating watering systems have gained wide acceptance.
- Water sources are restricted or become more expensive.
- Discharge of fertilizer water or high volumes of storm water becomes a liability.
- Fertilizer purchases can be reduced to half or less
- Effective and affordable water disinfection systems can reliably reduce the risk of spreading diseases.
Ponds
are often used as a simple way to catch rain and irrigation water for
irrigation use. Ponds can provide some degree of natural water cleaning
through sedimentation and biological activity. But the risks of transmitting
waterborne diseases, such as Pythium and Phytopthora, are considerable.
Even more troubling are cases where all crops watered from a pond were
quarantined because water from Ralstonia infested crops drained into
the pond.
Water from ponds should be tested regularly and treated properly. Crop
run-off is best collected and treated or discharged separately from
the main storage pond. This reduces the chance of recirculating diseases,
and makes it easier to treat the pond water to a safe level.
Check with EcoWorks about:
- Advantages, drawbacks and economy of recirculating watering systems for your operation
- Practicality of treating and re-using run-off from your crops
- What types of treatment are available and best suited to your needs, and at what investment and operating costs?
- Designing cost-effective, properly functioning recirculation and re-use systems.
Download Article and Chart “Recirculating Irrigation Water –
Is it Worth the Risk”
by Ratus Fischer
Download Article “Recirculating Systems: How do they Work, and Will You Have to Use Them”
Download Article “Troubled Waters?”
By Ratus Fischer in Grower Talks
11. Water Systems Integration
Obviously, all of the above elements are interconnected. Only by looking at all of them can the best solutions be found. It is a planner’s delight to start out with a clean slate. More often there are generations of existing systems with their problems, and plans for expansion that force changes. Often, partial or phased solutions are necessary and most cost-effective. But each step, each new piece of equipment should be part of an overall plan to make sure it will do the trick, and not be obsolete prematurely.
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