As a new season of spraying is now upon we should all take the time to think about the importance of our spray water quality is to the overall effectiveness of the spray itself as well as ameliorating the potential for any negative ramifications due to phytotoxicity.
 
Source – You water likely comes from one of a three sources: municipal, well or surface. Many people are actually using a combination of one or more of those sources. And a few are using rain water collected from rooftops or other sources. Municipal water is likely highly treated with chemicals and disinfectants and should be avoided as much as possible. I have reviewed a lot of municipal water reports over the years and the level of contaminants can be quite high – not illegally and “unsafe” levels, but undersirable at the vest least. If municipal is the only source available to you, use a carbon filter to remove as much contaminants, specially chlorine, as possible. Well water is likely much purer and with very few issues regarding use for spray water, although its alkalinity and hardness can be problematic. Lastly surface water (e.g., ponds, lakes, and streams) may also be fairly pure but can contain large amount of organic matter, be somewhat alkaline, and depending on the source, could contain contaminants due to runoff from neighboring farms, homes, or businesses.
 
Contaminants – contaminants can come in one of three basic categories: chemical, biological, and physical. Chemical contaminants can range from pesticide and fertilizer residue to industrial contaminants from old factories or neighboring businesses. Physical contaminants can be organic residue, dead animals, and garbage. Biological are usually microorganisms like E. coli or Salmonella spp. Each of these potential contaminants presents unique issues that can not only affect the safety of your crops, as well as the quality of your spray or irrigation water. We live in a time where there are very few pure water sources anymore. It always best to conduct a complete analysis of any new water source before using for any purposes.
 
Organic Matter (dirty water, solids) — many surface water sources have high levels of organic matter and siltation (clay colloids) that can adsorb and inactivate many materials. If you are using surface water sources for spray water you should be filtering with sand or membrane filters to remove organic matter and soil particles before it ever hits the tank. You can also consider the use of a settling tank where surface water is pumped into a large poly or metal tank where particulate matter can settle out before pumping (from the top down) into a spray tank. There are also settling agents available for many situations.
 
Microbiological contamination — this is more of a food safety issue than a spray water quality issue, but it is still important for growers that are using surface water for sprays. Generally, speaking surface water will have some level of microbiological contamination – that means measurable levels of generic coliforms, E. Coli, or Salmonella. If you are dealing with Listeria or Crytosporidium then you need to find a new water source or treat your source before utilizing. That said, unless you are spraying your crops with surface water just prior to harvest, most microbes will die on the crop surface before harvest.
 
pH – pH is a measure of the acidity/alkalinity of of a substance. Acidity is a measure of the amount of H+ ions in solution. The more H+ the more acidic. The alkalinity is a measure of the OH- ions in a solution. The ratio of H+/OH- determines the pH. The pH scale is logarithmic meaning that a pH 4 is 10x more acidic than pH 5 and 100x more acidic than pH 6. Many spray materials can degrade quickly at higher pHs due to alkaline hydrolysis, while others like copper should be applied in more alkaline solutions (>pH 6.5). The rub comes when you have compounds in solution that need different pHs – do you find a happy medium? Or do you spray separate tanks with different pHs? Many products are formulated so they are compatible with many other products and to resist adverse conditions. Others not so much.
 
Hardness — water hardness is a simple measure of the mineral content of a water and is measured in Grains per Gallon. It is a fairly simple test to conduct yourself or any water testing service can do it for you. A hard water is made up of calcium and magnesium carbonates, bicarbonates and carbonates. Hard water can cause some spray materials to precipitate and can reduce the effectiveness of surfactants, emulsifiers, and wetting agents. In worse case scenarios, materials can precipitate out and clog nozzles or filters. You can get a sense of the difference between hard and soft water if you’ve ever taken a shower or washed dishes using one then the other.
 
Alkalinity — Alkalinity is different from hardness in that we are now looking more closely at the buffering capacity of the water. In others words, its ability to neutralize acidity via calcium carbonate specifically. Measuring alkalinity is different than hardness and requires a different test kit, but is neither expensive nor difficult to conduct. The alkalinity of the water determines its ability to resist changes in pH.
 
Electrical Conductivity (EC) — EC is the newest concept to hit the spray water quality world. I personally learned about it when learning about the use of certain nutritional products and how too many ions in solution can cause levels of phytotoxicity or burning to vegetative tissue. In essence it measures the amount of salt or the salinity of your spray water solution – remember many fertilizer come in the form of salts. High levels of salinity above (e.g., NaCl >1000ppm) or ECs >500-1000 microsiemens can cause precipitates, chemical inactivity, or phytotoxocity. Much of the information that currently exists specific to spray materials is for herbicides, but we are learning more every day. Measuring ECs is not difficult but does require a more specialized (and $$) device. More on this in a separate post.  
 
Temperature – water that is too hot can accelerate the breakdown of some materials, while water that is too cold can restrict solubility resulting in an uneven tank mix.
 
Structured Water — There are a number of new research areas that are coming to the forefront of how we monitor and work with water. In general, there are very few areas of the world where water (in any of its phases) can be considered “pure.” Even water high in the Himalayas has been found to contaminated with industrial pollutants coming from China. We all know about issues New York’s water supplies have been through and are faced with, even right here in the Finger Lakes. That said, its fair to say probably none of use are working with pure water. So, in addition to all of the basic measurements and adjustments we can make as described above, restructuring water is also something very important that we can do to increase the intrinsic and energetic quality of our water. It goes outside of this article to get into structured water, suffice it to say that the use of biodynamic stirring, use of flow forms, waterfalls, and special restructuring instruments can have a profound influence on the quality of the water. What are we doing when we restructure water? In essence we are reestablishing the sheeting or matrix characteristics of water molecules (water is not just a bunch of water molecules randomly commingling with each). As well, we are remove the impurities such as chemical imprints from the water bringing it back to as pure as can be.
 
What to Do?
Test Your Water – Whether do it or you hire someone to do it – TEST YOUR WATER! Start with a basic water testing program. This can start with your consultant or farm manager – or you can hire a specific water quality testing outfit to come on site to conduct testing. That said, for a few hundred bucks you can set yourself up to have everything you need (outside of microbiological testing) to monitor water quality at your farm.
 
Read the Product Label – they print those things for a reason. In addition to rates and safety information, they can tell you a lot of about the water quality conditions required for the spray material you’re about to put in the tank. They can also tell a lot about what you can and can’t mix in the tank with the specific material. Yes, many modern materials are manufactured to be mixed with a wide range of materials. But they can’t cover all bases. And with so many new and funky biological and holistic materials out there, please read and then…..test.
 
Compatibility Test – So, before you dump $100s of materials into your tank, do a compatibility test. Though some folks think these are something out the Flintstones, they can tell you a lot about what may go wrong before you waste a ton of time and money. Take a clear jar, filly it ¾ with the water you plan to spray with, add a proportional amount of each spray material you are going to use in your next spray, and shake vigorously. Then watch – Did it precipitate? Did it foam? Did it explode? Did something else happen that doesn’t look right?
 
Bottom line is to pay attention to the most important thing you put into your spray tank – the water. This can make or break your day and save you a ton of time and money along the way. Know Your Roots is equipped to help you with your water testing - though we may need to lean on a lab for the really technical testing (e.g., chemical contaminants).