Will Cloud Seeding - Stop Hail - Start Rain or Prevent Lightning?
December 13, 2008
What is the future for weather modification? Can scientists cause it to rain more or less on one area than would normally occur? Can devastating crop ruining, hailstorms be turned aside? Some weather scientists say weather modification is feasible, others are inclined to be doubtful.
Those who take a restrained point of view, such as the U. S. Weather Bureau. say:
- There must be suitable moisture bearing clouds available for cloud seeding. Obviously then cloud seeding is not a cure for drought.
- It has been possible to say definitely that cloud seeding has increased precipitation only under very favorable circumstances, such as where moist air currents are forced to rise and produce persistent clouds. These circumstances usually occur over mountain ranges in the West. Under these favorable circumstances an increase in precipitation is only 10 to 15%.
- More research is necessary to learn how clouds release their moisture naturally before the effectiveness of artificial methods can be definitely known. One point of view holds that conditions under which it appears possible that cloud seeding might cause an increase in precipitation are almost exactly the same as those required for natural release.
On the other hand, Dr. Irving P. Krick, whose Water Resources Development Corp. conducted cloud seeding work for almost a decade, says:
- Unlike other natural resources such as iron ore, the world supplies of water cannot be depleted. Our water supply is continuously moving through the hydrological cycle, from the atmosphere to earth as precipitation and by evaporation back to the atmosphere. It is an astounding fact that we are using the same water that prehistoric man used. The problem is to adjust and modify the water supply through precipitation to best fit our needs.
- It is true that cloud seeding cannot produce rain but it can assist the natural processes and thereby obtain greater yields in desired areas.
- In the wheatlands of eastern Washington, live successive years of cloud seeding obtained from 6 to 14 more inches of rainfall than adjacent areas. On a cost basis spent on weather modification added $40 in income to farmers through increased yields.
- Hail cannot be eliminated but it is possible through cloud seeding to suppress it and minimize potential damage. Hail suppression programs will increase precipitation and at the same time suppress lightning, thus saving timberlands from fire.
Meanwhile it is interesting to note that cherry growers in Yakima, Wash, recently went on record favoring a bill which would provide regulation of weather modification. They are worried that the attempts to increase rain on adjacent dry land wheat farms will ruin their cherry crops.
The interesting part of this article is the original publication date - April 1957. Fifty years later the same topic continues to be discussed - can man control the weather. Only the future will tell us for sure.
Tuning Airblast Sprayers
February 7, 2008
We tend to take the blowers for granted. The propeller blades just keep turning and blowing the air, but what we don’t realize is that they need to be checked periodically and cleaned, to remove the residue that cakes up on the surfaces and makes them less efficient.
There can also be nicks and cracks caused by picked-up debris and fatigue, which can throw the propeller out of balance and produce vibrations. These vibrations usually affect the chassis and the tank to the extent that I have seen steel tanks crack and break or pumps break loose because of those vibrations.
So, when you’re cleaning out filters, inspecting hoses and checking nozzles, take a good look at the blower: clean the blades (you may have to scrape them), tighten the bearings, lubricate the moving parts and check for loose bolts and broken brackets.
Low Rate Spraying Technology - When Is Less Better?
January 24, 2008
During the years I have been teaching sessions on Spray Application Technology, I have many times opened up the session with a big poster that says: MORE IS NOT BETTER.
I have used that phrase to illustrate the need to reduce spray volumes and try to keep the spray material on the foliage and not let it dribble down onto the ground. And that is fine when you are spraying pesticides and nutrients on crops that you want to develop and grow.
But what about when you want to kill weeds. For years now, we have seemed to favor pouring everything but the kitchen sink at the weeds, hoping to eradicate them forever, and in our zeal we have used a lot of herbicide and a lot of water, thinking that, in this case, More IS Better!
Well - More may be better in some cases, but stop to think for a moment as to what we really want to accomplish when we spray herbicides: Kill the Weeds? Yes, but are we going to get results giving them a bath or will we get a better kill by making sure that the expensive materials we are applying stay where they are supposed to: ie:: on the plant?
L.T.R.
Enter Low Rate Technology a phrase coined by Monsanto to promote the more effective application of their new formula Roundup Ultra.
Low Rate Technology is nothing more and nothing less than just reducing the amount of water you mix with the herbicide and apply less volume on the crop, while maintaining the per acre rate of the chemical.
Because Roundup Ultra is an enhanced version of the old Roundup into which they have added surfactants, stickers and stabilizers and thus made it more user friendly, rainfast and improved the way it distributes on the foliage and gets absorbed by the stoma, it is ideal to apply with this new Low Rate Technology.
And you can adjust this Low Rate Technology to suit yourself as long as you keep the “per acre” dosage of the herbicide relatively constant. In other words, if you are presently using Roundup mixed at 0.5% and putting 2 quarts into 100 gallons in your tank and applying 100 gallons to the acre, you are effectively applying 2 quarts to the acre. You can re-calibrate your sprayer and reduce your application to 25 gpa or even down as far as 10 gpa, but always keeping the 2 quarts to the acre dosage.
What you accomplish with this is:
- Better effectiveness of herbicide because it stays on the plant and does not run off.
- Time and Labor savings due to fewer refills. Your sprayer can cover up to four times the acreage in one day as you reduce the number of time consuming fill-ups, and we know how the clock keeps running during these “pit stops”.
- You radically reduce the amount of herbicide leaching into the ground.
Does that benefit us all? Yes!
What you can’t accomplish with LRT is:
- Apply pre-emergents. Most pre-emergents need water, so this would be one case where LRT is not applicable. However, even though they are listed on the labels, these pre-emergents should not be used in conjunction with foliar herbicides in LRT because the absence of water will not allow them to run off onto the soil.
- Soil incorporation. Plenty of water is a benefit in this case as it helps carry the material into the treated areas and retards evaporation, especially in warm soils.
A word of caution: When mixing different herbicides together, make sure that you know how they work and that they will be working in conjunction. i.e.: use the foliar formulations together and the soil application formulations together. Don’t mix foliar with soil unless specifically recommended by your crop advisor or extension agent.
Generally, when you mix a soil and a foliar, depending on your method of application, only one will work and you’ll be throwing away your money on the other.
Calibrating for LRT:
These are the basic rules for Low Rate Technology application:
Calibrate your sprayer to apply between 10 to 25 GPA as this is the volume range that has given the best results. Make sure that your sprayer can maintain the volume you have calibrated it to. Nozzle type and size, spacing, pump pressure and field speed are all factors in determining this spray volume.
- Use flat fan or low volume flood nozzles. Lowering volumes by merely increasing field speed will may decrease control effectiveness. It is very important to use small orifice nozzles.
Flat fan “Extended Range” (XR 11015 to 11003) and low volume flood (TK-SS.75 to TK-SS1.5) are recommended. They produce small, highly concentrated droplets which are uniformly distributed and adhere tightly to the leaves.
This results in better coverage and improved control of target weeds. Also recommended, especially when drift control is a factor, is the use of Turbo-Drop drift control nozzles which will enhance the effectiveness of the coverage while dramatically reducing spray drift.
- In-line filtration is very important to LRT success. Since the system uses small orifice nozzles to reduce the application volume, 100 mesh in-line filters must be used to assure proper nozzle operation.
- Always use clean water. Using water drawn from ditches, ponds, etc. will clog the filters and reduce the effectiveness of the application.
- Prior to spraying, set the height of the boom so that there is a 30% to 40% spray pattern overlap before the spray hits the top of the leaves.
- Apply at speeds no higher than 5 mph. The speed of the sprayer should be slow enough to ensure proper coverage. High speeds can stir up dust, make the boom bounce and cause an irregular rate of application, as well as distract the driver from properly monitoring the situation.
- Maintain spray pressure of 20 to 30 psi (depending on the type of nozzle). Too low pressure will not propel the spray into the foliage. Too high pressure will pulverize the material, causing it to drift or evaporate.
Other Pointers:
Use sticker-spreaders generously with your contact herbicides. Of course read the labels first and check the formulation to see if the material already has surfactant materials added to it (such as the case of Roundup Ultra).
Sticker -spreaders will improve the coverage and give you a certain "staying power" on the leaves. You don’t worry about phytotoxicity in these cases because, after all, your want the weeds to die and never come back! (Sort of reminds me of the
Electric Chair being labeled as "cruel and inhuman punishment").
Check into ways to "fine tune" your materials. Consult with your suppliers on water treatment such as pH levels to increase potency of the product.
Don’t add acid to Roundup Ultra. Follow the label and add ammonium sulfate to your tank mix. Acid won’t do anything to improve its effectiveness, but ammonium sulfate will.
Give this Low Rate Technology system a try. It should give you good results and at a fraction of the cost of your present program. And, once you get a "handle" on the LRT program, you can experiment with reducing chemical rates and save even more.
Low Rate Technology really comes into play when you are applying herbicides with other types of equipment such as CDA (Controlled Droplet Applicators - Herbi), wiper and sponge applicators, etc. Here the proportions of herbicide mix to water are usually between 30% and 75% and, in some cases, 100%.
When coverage, either as a Ultra Low Volume spray from the CDA or as a direct contact and "wipe" by the panel type equipment, is good, the results are impressive. However, many times it is necessary, due to a host of reasons, to go over the targets a second time to assure that the chemicals have gotten on the foliage.
Consequently, we recommend first that all wiping and CDA applications be done at lower speeds and with care and patience to assure coverage. Unless you are using a tracer dye, you generally won’t be able to tell for sure if your coverage is good, so take your time and get it done right the first time.
Which brings me to the subject of Chemical Mowing
For those of you not familiar with the term, it is in essence, applying a herbicide as a dilute to work as a growth regulator and generally reducing by one third, the times you have to run the Bush Hog. Chemical Mowing is being used quite successfully in citrus groves in Florida, Texas and California, as well as in Brazil and is basically done with panel wipers, rather than sprayers.
The panel wipers, generally mounted on the front of tractors, are run through the rows between the trees at higher speeds and transfer through contact a small amount of herbicide to the growth that reaches their height. This keeps the weeds controlled and replaces the need for mechanical mowing, at least temporarily.
Injection Systems - Agricultural Spraying, Applying Chemicals and Fertilzers
January 14, 2008
Injection Systems offer new safe ways to avoid mixing, loading mishaps and messes when spraying applying fertilizers and chemicals.
Did anyone tell you that in the very near future, regulations are going to control the way we mix pesticides and load sprayers in ways we haven’t imagined! And we are not going to be able to carry mixed loads down the road to the field or between the fields we are spraying!!
The result of all this eventually, will be that we are going have to inject the pesticide into the pressurized spray line somewhere between the pump and the nozzles.
GREAT! No More Agitation Headaches!
The up-side of all this is that the injectors will carry the materials right out of their original containers into the flow and out onto the crop. Mixed liquid will not recirculate into the tank and therefore the tanks will be clean. Relief valves in the main pump will carry only water back into the tanks, the excess that is by-passed by the pressure control units.
“Mixing and loading” will be limited to water treatment, such as adding surfactants, pH buffers and stickers. (on second thought, some of these are messy, and so some residue will stay in the tanks, but none of it is really toxic.)
The spray equipment will have to be modified to include areas where the containers of concentrated chemicals can be placed to feed the injectors. Sprayers will have to have banks of two or more injectors to allow the injection of two or more chemicals that are normally used in combination with each other in current tank mixes.
Applying soup mixes (combinations of insecticides, fungicides, nutritionals) will become impractical and too costly. (This, in my opinion, is a blessing, because many of those soup mixes combined chemicals that actually “cancel” each other out; but who is going to convince the grower of this, when he maintains that it has worked for him for years).
The chemical suppliers will be reformulating and packaging their materials in user-friendly containers and there will be a proliferation of injection systems on the market, as well as the usual complement of “gimmicks” designed to make the operation more effective, safer and economical. Wettable powder and soluble granule formulations will have to be converted to flowable combinations that can be handled by the injectors.
And high pressure sprayers will have to add a booster pump to elevate the pressure to working levels after the injection stage, because the cost of a high pressure injection system would be prohibitive and impractical.
One of the basic concepts in injecting chemicals into a stream (in this case the spray hose), is to keep the proportion of the injected material as close to the specification as possible. Consequently, because the flow of spray will not be constant due to nozzle controls, pressure variations and other operator changes during the spraying process, the injector should be a proportioner that will adjust to the variations in the flow.
There are different types of injectors on the market, but only those that are driven by the actual flow in the line will proportion as well as inject and react to changes in the flow rates.
In other words, electric and vacuum (venturi) injectors will not assure the accuracy of the mix of spray chemicals if the flow rates and pressures in the spray lines are not constant.
Flow-driven injectors such as the Dosatron and Dosmatic are ideal for this type of installation because they are non- electric (powered by the actual flow of the line they are injecting into), simple, accurate, chemical resistant and easy to maintain and service.
However, these proportioners were designed for low pressure systems as they basically were meant to be used in irrigation systems, which rarely operate over the 100psi pressure level, and more likely run at about 60 to 70 psi.
The Dosatrons and Dosmatics are very accurate and easy to calibrate, generally from 0.2% up to 2.5% and in volumes from practically ounces per minute up to 100 gpm, and, being non-electric (water driven) they are virtually trouble- free.
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As a matter of fact, these units can be set up in tandem to proportion 4 or 5 chemicals into the same flow and mix them in the order that the manufacturers recommend, for a well-balanced final spray solution.
This system will work very well with the large boom sprayers and herbicide applicators that operate at pressures under 100 psi and can be just “plugged” into the spray lines beyond the pumps and relief systems. A back-flow prevention device will have to be placed in the line between the pump and the injectors so that the mixed solution does not have a chance of being flushed back into the tank and fill systems.
When the sprayer operates above 100 psi, a booster pump will have to be added after the injection station to take the pressure up to the required level for the nozzles. This would be on boom sprayers operating above 100 psi, air-blast sprayers and mist sprayers that require high pressures to generate fogs or other small droplet patterns.
These pumps would be the current pumps on the machines, such as piston, plunger or diaphragm units and would have to be re-plumbed to kick-in after the injection process.
There will be a host of other injection systems and proportioner pumps being made available either for retro- fitting or as original equipment on new sprayers. Some of these pumps generate high pressures and thus can be installed after the main pressure pump on high pressure units.
However, even though they are very accurate in the flow that they deliver and can be calibrated to exacting specifications, the proportion of the material that they are injecting into the spray line can change with the normal changes in pressure and flow caused by variations of the pumps, pressure relief valves and shutoffs, especially in on-off cycling applications such as Smart Sprayers, Tree-Sense, Tree-See and other specialty applicators controlled either by computer or operator.
A possible solution to this type of situation is to have the injectors feeding into a holding tank from where the mixed solution is then pressure pumped to the nozzles. This tank would act as a compensation chamber and the proportion of mix solution in it would be always constant to what has been set by the operator.
The Relief Loop
Another consideration in the use of pressure pumps after the injection point is that their relief system will have to loop back into the pumps own inlet valves, very much the same way that pressure washers are plumbed, because the excess coming out of the relief valve is a mixed solution and cannot go back into the fresh water tank. This may also require another backflow preventer to protect the injector pumps and keep the pressure down in the holding tank.
Outlook
It may take some time for legislation to mandate these changes to the way we are running our spray machines. If you operate at pressures below 100 psi, you will not be facing major changes. If, however, your machines are high pressure units, you will be looking at some important modifications and alterations to your present equipment.
You might want to look at the use of drift control nozzles and lower pressures and do some testing of your own to see if you can get the coverage and results on your crop that until now, you thought you could only achieve with high pressure fogging or atomization.
Meanwhile, the first indication of these sweeping changes will be the wider use of pre-packaged chemicals: soluble packs and pre-measured containers. The market will see manufacturers offering “quick-fill” systems and special collar systems that practically eliminate spillage and even contact with the materials. And you will be urged to mix what is necessary to treat the specific field and not transport it out on the roads to other locations.But, unless something earth-shattering happens to our system of government, the implementation of the rules is still a ways down the road, if WPS is any example.
Air-Assist Spraying of Crops
January 7, 2008
Much has been said and done over the past thirty years to improve the efficiency of air-blast spraying. Improved fans, oscillators, baffles, even electrostatics, have all contributed to better coverage and penetration especially in the orchard and tree-crop areas, where air-blast machines are the industry staple.
However, when it comes to spraying either horizontally or vertically down, as in the case of row-crops, vegetables and nursery stock, air blast sprayers generally lack the ability of delivering good coverage to the undersides of the leaves and many times are not effective in treating infestations.
Hence, they can be relegated to maintenance work such an application of nutritional and preventive fungicides and insecticides, but when eradication is needed, in come the old style boom sprayers!.
But take heart, several spray professionals (including yours truly), have been working over the years to develop systems that would delivery the spray material to the heart of the plant canopies and attain the coverage that could allow us to use air-blast machines to control infestations, especially in difficult to penetrate crops.
The Concept of Air-Assist Spraying Goes Way Back
The concept of Air-Assist spraying in which the droplet pattern is sprayed into an air-stream directed at the crop goes back before the development of the Air-Curtain (Degania/FMC) type boom sprayer. This machine was effective for open and simple canopy crops such as cereals, wheat, barley, corn, even cotton, where the cloud of spray could drop down into the crop and, through turbulence, cover most of the plant surfaces.
However, when you got into vegetables: cucurbits, melons, tomatoes, soy, beans and other tight canopies, the coverage just wasn’t there. The same held true for the “cannon” sprayers that delivered their pattern laterally and could not get the droplets to penetrate the canopies, much less cover the undersides of the leaves.
Cannon sprayers produced relatively small volumes of air at high speed, which reduced the inertia of the blast and therefore curtailed its ability to displace the air that was already in the way (between the sprayer and the target) in order for the spray material to reach its target. Consequently, forward speeds had to be lowered to increase the sprayer’s reach.
Growers were buying tractors with “crawler gears” and putting out higher volumes of spray than they had originally intended, in order to get the job done. And an extra added headache to all this was the considerable amount of uncontrollable pesticide drift that these machines generated.
Cannon Sprayers - Relatively Efficient Portion of Delivery
The cannon sprayers did have a relatively efficient portion of their delivery: those machines that had supplementary “horns” under the main cannon designed to reach the crops close to the sprayer, were getting good coverage on the plants sprayed by those “horns”.
The reason was that the “horns” were aimed into the crops at an angle and the air pattern coming out of them was relatively close to the targets and directed straight at them. Thus the spray was penetrating the foliage and covering most of it on both sides.
Three years ago, the writer developed a “directed spray” system for use on melons, by modifying a sleeve boom air sprayer into a duct boom sprayer with drops that ended in horns that were oriented directly at the crop. These horns held the nozzles so that the spray was injected into the air stream and the horns directed it onto the crop.
By orienting the horns at a 30 degree downward and 30 degree inwards (towards the crop in the bed) angles, the coverage obtained was far superior to anything attained previously with other systems.
This technique proved that the air assisted spray had to be aimed directly at the canopy and relatively concentrated so as to be able to penetrate the foliage and, once inside, create enough turbulence so that the droplets in the pattern reached all plant surfaces.
The Concept of “Directed Spray”
The concept of “directed spray”, long in use with standard boom/nozzle sprayers, has now been developed by several sprayer designers and manufacturers, including AirTech Sprayers of Winter Haven, Florida and is based on the use of directed “horns” that come off an “air-boom” which is a cylindrical duct that is held horizontally by the boom.
