My main expertise is in water movement and wastewater treatment in the field; I especially love applied science that works for the professional in the field. I invented the Aardvark Borehole Permeameter and Soilmoisture heard about my invention and contacted me. I was truly impressed with their flexible technical staff who, after much work on their part, turned my design into the world's only automated Borehole Permeameter: tough, portable, reliable, highly accurate, and complete with software. Still known as the Aardvark, it is now sold worldwide through their extensive global network. I am proud to have my name and invention associated with Soilmoisture Equipment!

Thomas Macfie,
Inventor of the Aardvark Permeameter



excerpt from the Soil Report Newsletter of Soilmoisture Equipment Corp.

Twenty years ago, when Dave Koontz first saw the land that was to become his ranch, it didn't look like much, just a coastal hillside covered with scrub brush and dry as a skeleton. It would take a whole lot of water to grow anything there. But Dave thought it had possibilities, like a nice place to retire to.

He had worked his whole life in the aerospace industry and now in the late 1970s with his three boys about out of the nest, it was time to plan for the future. A little ranch and some avocado trees would keep the wolf away and give him something to do. So he and his wife, Marilyn, drove up from their home in Malibu to Ventura County, north of Los Angeles, and purchased 34 acres in Somis.

Dave Koontz retired in 1996 after 34 years with Hughes Aircraft as manager of the Hughes Weapons Systems Evaluation Laboratory at the Naval Missile Test Center at Point Magu and 10 years with an engineering service firm.

"I attended classes held by Bud Lee, the county farm advisor. He was big on avocados and saw them as a high dollar crop."Dave made a study of the avocado, as he does with most endeavors. The avocado had a niche in the marketplace and definitely a future. Using information supplied by the California Avocado Commission in Santa Ana, he discovered there were over 57,000 acres given over to avocados, mostly in Southern California, but some in Florida. These acres produce about 340 million pounds of fruit annually.

"I guess I'm lazy, but what I liked best was that I wouldn't have to prune as much as is done for citrus trees--or spray for bugs. Avocados were less work, easier to grow." There is another aspect to the avocado which appealed to Dave. The fruit doesn't ripen on the tree. It has to be picked first. So, the grower can pick his Hass crop anytime between early December all the way till the next September or October.

There are a number of recipes calling for avocado, but in the U.S. most are used in salads and guacamole sauce. There are lots of calories in the fruit, but no cholesterol, making avocado oil for cooking increasingly attractive. The avocado pulp can also be prepared into guacamole sauce, then frozen.

Picking the crop is like a crap shoot at Las Vegas. Dave Koontz explains: "The early and late crops get the highest prices. But to be declared mature, the fruit must have 8 per cent oil. This is a state requirement in California, not Florida, however. The grower takes his risk, has a sample tested and then picks the fruit early. Eight per cent oil and he's home free. Less? He takes a loss when the packing house throws it out!

"Risks occur when the crop is left on the tree, waiting for higher prices. If it works-- fine, but what if the trees are stressed and fruit drops and is bruised or there is a killing frost or a wind storm--the greatest risk to the avocado grower? It all makes for some exciting moments in the avocado orchard."
Dave acquired the land in 1978, had it graded and developed, and in 1979 planted avocado trees, 3,000 of them. As the trees grew, he thinned them. His count is now 2,400--and producing approximately a hundred pounds per tree.

"You have to understand that we started from scratch. There was just a hillside and undergrowth, no road, no water or electricity, nothing. We were atop the Fox Canyon aquifer, but to tap into it we had to drill a well.
"At first we tapped into a community well, but in 1989 we drilled our own. We went down 1150 feet at a cost of $80,000 and then invested another $80,000 in the pump, electrical and distribution system.

"Then there was the high cost of pumping the water for irrigation. In the early 1980s, the summer electric bill for pumping from the community well was $2,400 per month. Hopefully it won't get ahead of my story if I report our electric bill today is half that amount.

"I knew water couldn't be wasted due to pumping costs and concerns for preservation of the aquifer. Guess work was too expensive. From the outset I kept asking if anyone had automated water use so the right amount was applied at the right time. Nobody had. But I wouldn't give up on the idea. I had all the irrigation lines in all six blocks converge at a single location, and had electric valves installed. There really was no reason to do this, but automating the system was a dream of mine.

"I looked into various forms of sensors and instrumentation, but quickly became disenchanted. Then I heard about tensiometers."
First invented in 1912, the tensiometer is a fool-proof way to tell when a plant needs water. Below ground, water clings to the soil in various sized "pores" or "capillaries". When the soil is wet, most of the large pores are filled with water, easily obtainable by the plant root. As the soil dries, the water is held in ever smaller pores and under greater tension. It is as though the soil doesn't want to give up the last of its water. Plant roots are unable to break the "soil suction" to obtain water and thus wilt and die.

The tensiometer accurately measures the suction or tension under which the water is held. A gauge reveals when to water and when to stop watering.

In typical fashion Dave Koontz made a study of various brands and models of tensiometers. Did he ever! He may know more about the design and construction of tensiometers than Soilmoisture engineers, going on about the advantages of O-ring construction and the usefulness of the water reservoir on the device.

"I looked at all the various brands and quickly saw that the tensiometer made by Soilmoisture Equipment Corp. was by far superior. It was better designed, easier to install and use, and far more reliable than others he tried. The water reservoir on the top with a quick fill plunger enables you to restore the water in the tensiometer very quickly while checking the irrigation system. Much less maintenance was required, even then parts are available and easy to install. The whole ensemble didn't have to be returned to the factory for repair or scrapped when broken.

"I use two or so tensiometers in each of my six blocks of trees. I've been most pleased with the results."
He gives an example. "One area of the ranch simply didn't produce as well as others. Upon installation of a tensiometer in this area, he found it kept drying out when other sections were still wet. It turned out it had sandy soil, while others were more clay. It didn't need more water, in fact it needed less, but it needed to be watered more frequently. Only a tensiometer could reveal that. I made this a separate block and the customized irrigation resulted in dramatic improvement in tree vigor".

Dave Koontz still wasn't satisfied with his system. It wasn't automatic. Why was that important? After all how much work is involved in reading a dozen or so gauges and turning on the sprinkler system? Dave says the problem with manual routines, like taking soil moisture core samples, reading tensiometers, or tending truck or tractor batteries is the farmer is pressed with other chores and forgets to do it, reverting to guesswork on irrigation.

Perhaps it was the aerospace engineer in him--he wanted it automatic, untouched by human error--but he gives a couple of more down-to-earth reasons. Suppose he went away for a few days. Who'd read the gauges?There was an even better reason. He determined from his utility company, if he pumped water for irrigation between midnight and 6 a.m., he would cut his electric bill by almost two-thirds. With daytime pumping costing between $80 and $125 per hour per acre, that is no small saving. And who wants to man the sprinklers in the wee hours?

Dave said that "more than the nice design of the tensiometers, the optional replacement of the pressure gauge with a 4-20 mA current transmitter to interface with a computer made automation of his system possible". Particularly important to Dave was Soilmoisture's use of the industrial standard technology of the 4-20 mA current loop in their transmitters. Dave has standardized on this technology for all the sensors on his ranch due to the accuracy and reliability of signal measurements taken from great distances on the ranch. He measures pressure in water tanks (for water level) and flow of water in main and irrigation lines.

Dave hooked his Soilmoisture tensiometer with the 5201 Current Transducer installed to a computer which monitors the soil suction constantly and turns the sprinklers on or off as needed. Dave uses a Macintosh PC combined with a small pre-processor to process incoming signals. What is special is the custom software he uses. The color displays present, in very straight forward graphic pictures for a farmer, the status of soil moisture measurements, height of water in tanks, state of valves, and digital readouts of all measurements. Dave's computer even displays and stores for future reference the soil moisture vs. Applied water each day on a monthly plot for each irrigation block. His avocado trees get the precise amount of water they need for optimum production--untouched by human hands. Even better, the computer remembers the daytime water needs and turns on the irrigation system at midnight, off at dawn. The savings in electrical costs is significant, not to mention sleepless nights. If nighttime irrigation doesn't deliver enough water, the computer keeps the system running in daylight till it does.

The start-up costs for Dave Koontz' system may be substantial, but it saves him money every day. How this happens is explained by Lowell Preston, coordinator for the Fox Canyon Groundwater Management Agency. Its job is to conserve and use efficiently the huge Fox Canyon aquifer along the Ventura County coast."All a farmer has to do is drill a well and pump water," Preston says. "The water is free and he can use as much as he wants--as long as he uses the water at 80 per cent efficiency."That is a very big "as long as". If the farmer fails to reach 80 per cent efficiency, that is wastes water, it is not longer free. He pays, better said, is penalized, hundreds of dollars per acre foot for all the water he uses.

How does the Fox Canyon Agency know when water is being wasted? Using a formula developed at the University of California at Davis and adopted by the state, the agency knows how much water is needed by every crop from grass to, well avocados. Pump more water from the aquifer than needed in a year, and the penalties are in effect.

Thus, the screws are slowly being turned, forcing Ventura county farms to use water wisely and efficiently. Dave Koontz is way ahead. "I have never paid a penalty or even come close," he says. Lowell Preston adds, "I am impressed with Dave Koontz' operation. It is one of the best systems we have to maximize irrigation."Certainly in California, but all over the world really, farmers are facing increasingly high costs for water. If it ever was free, it is no longer. Conservation is the norm. Waste not, want not--or, waste and lose your profits into the ground they came from.

Maybe it takes someone like Dave Koontz to show the way. Maybe on a space engineer, used to technology and trusting instrumentation over human instincts, could come up with his automated system. And maybe it isn't for everyone. But he sure is pointing to the future.