KelwayPHD Soil PH Meter

A pH soil meter that is quick & easy to use, is accurate and is highly durable - what more could one want? The only "negative" is that only tests for a relatively narrow pH range, albiet this is the range most typical gardeners are concerned about. Very few plants like alkaline conditions, so testing for anything above a 7.0 isn't very useful anyway. For what it does, it's hard to beat the Kelway - I've tried a number of cheapo (some not so cheap) soil testers and I'm rarely confident in their accuracy. But with the Kelyway, after I've watered the plants, I take a couple of quick readings that I can be confident about. With blueberries, the pH range is critical - so when I'm watering and if my soil tests a bit above 5.5, I know I need to add more acidified water immediately. If your goal is to quantify how alkaline your soil is so that it can be lowered to 8.0 or less, the Kelway is not your instrument - but for the rest of us, most of whom are dealing with slightly acidic to neutral soils, the Kelway is ideal.

Nice instrument. My initial impressions were quite positive. After cleaning the probe surfaces per the instructions (a very simple task), I tested my soil in several (about 20) different locations. I am planting acid-loving plants (blueberries), so I had previously conditioned the soil to bring the soil pH to within 4.5-5.5. This meter showed me which areas needed further treatment, and which areas were good to go. The meter settled on a reading quickly and remained stable until I removed the probe and wiped it down to prepare for the next reading. It turns out that my untreated soil averaged between 6.0 and 6.5. My conditioned areas were mostly right where I needed to be -- around 4.8. It remains to be seen how this instrument will hold up, but I expect it to provide years of service. Stay tuned.

Meter seems to function as advertised. Simple to use and seems to be very accurate. Would purchase again. An excellent adjunct for the home gardener.

I am growing bamboo in San Francisco and my neighbor's redwood tree sheds over my property.After taking hold, my bamboo started turning yellow with dead leaves and dry stalks.I suspected the soil was turning too acidic. I could add lime of course but without properlymeasuring the PH level first, I could just as well over do it in the opposite direction.I looked far and wide for a practical PH meter that is accurate and allows for quick readings at multiplespot in my garden. This allows me to track the Ph at different locations but also its evolutionin response to the addition of organic lime.This unit is sturdy, easy to use and I can take 10 measurements in < 1hr.I almost bought the more sophisticated units a $200-$300 but I am very happy with this unit.Keep in mind that the measuring scale is mostly on the acidic side with just a modestrange on the alkaline side. Most gardens have a problem with excessive acidity so that shouldnot an issue.

This soil pH meter is wildly inaccurate. If you are trying to adjust your soil pH based on this meter, you will be led completely astray. I researched this meter before buying it, and as a result purchased a pack of the "conditioning films" and a calibration solution test kit from Atlas Scientific with the same order. I read all instructions and followed them precisely. I even used separate conditioning films on each of the two metal rings to insure there was no metallic cross-contamination between the rings. When reading the meter, I interpolated between the 0.2pH scale markings to make readings with a "resolution" of 0.05pH.First test: When placed in the 4.0pH calibration solution, the Kelway meter read 5.20pH. Hunh.The Kelway instructions state, "Use when the soil is damp. No current can flow in soil that is very dry." and "Press the soil tightly against the metal rings." Clearly, the Kelway meter is not intended to be used in fluid samples. I thought perhaps the meter would not work accurately in a completely fluid solution.So, I took a large soil sample and "homogenized" it as thoroughly as possible. I placed a measured amount of this sample in each of three clean glasses. To sample A, I added a measured amount of distilled water. To make sample B acidic, I added an equal measured amount of the 4.0pH calibration solution. I then mixed a solution of powdered dolomite limestone and distilled water. To make sample C alkaline, I added an equal measured amount of this solution. I then measured all three samples with the Kelway meter, taking readings on 1 minute intervals. A subset of the readings taken in this second test is shown below:1 min: A - 6.40pH, B - 6.30pH, C - 6.60pH.3 min: A - 6.50pH, B - 6.50pH, C - 6.70pH.6 min: A - 6.60pH, B - 6.60pH, C - 6.75pH.These readings left me with no confidence in the accuracy of the Kelway meter, so I ordered a Rozway Digital pH Meter. This meter is provided with packets of powder that allow you to mix calibration solutions of 4.01pH, 6.86pH and 9.18pH. The instructions call for the use of deionized water in these solutions. I had only distilled water available, which is not the same thing, so my calibration of the Rozway meter may not have been fully accurate.When placed in the Atlas Scientific 4.0pH calibration solution, the Rozway meter read 3.86pH. Hunh. Not the specified +/-0.01pH accuracy.I then mixed the three Rozway calibration solutions and performed the calibration procedure. After calibration, the three solutions read: 4.01pH, 6.91pH and 9.04pH. Two of these readings are outside the specified accuracy of +/-0.01pH, but that may be my fault due to the use of distilled water. After calibration, the Atlas Scientific 4.0pH test solution read 3.91pH. I then tested the three Rozway solutions with the Kelway meter and measured 5.10pH, 5.15pH and 5.40pH.The instructions for the Rozway meter speak of "immersing the electrode into the solution". Obviously, the Rozway meter is not expected to work with soil that is merely damp, as is specified for the Kelway meter. So I added two more measured quantities of the specified fluids to each of the soil samples described above. This turned them into slurries. I made measurements in this third test by stirring the slurries and inserting the meters (I tested both, individually) before the solids settled out.The Rozway meter read: A - 6.82pH, B - 5.95pH, C - 7.32pH.The Kelway meter read: 1 min: A - 7.00pH, B - 6.60pH, C - 7.05pH.In truth, I had expected a wider range of pH readings among the three samples. However, I do have confidence that the Rozway meter readings are accurate to perhaps +/-0.1pH. At best, I would place the accuracy of the Kelway meter at +/-1.5pH. Clearly, the readings obtained from the Kelway meter are more dependent upon the "fluidity" of the sample and the "settling time" allowed, than they are on the true pH of the soil sample. The pH of soil sample A should not have changed between the second test (one measured quantity of distilled water) and the third test (three measured quantities of distilled water). Yet the Kelway reading changed from 6.40pH to 7.00pH. In the second test, the Kelway reading for sample A changed from 6.40pH at 1 minute to 6.50pH at 3 minutes to 6.60pH at 6 minutes. The pH of the three soil samples (Rozway readings) was: A - 6.82pH, B - 5.95pH, C - 7.32pH, a span of 1.37pH. The pH measured by the Kelway meter (3 minutes, second test) was: A - 6.50pH, B - 6.50pH, C - 6.70pH, a span of 0.20pH. The pH measured by the Kelway meter (1 minute, third test) was: A - 7.00pH, B - 6.60pH, C - 7.05pH, a span of 0.45pH. To re-state my conclusion: the readings obtained from the Kelway meter clearly are more dependent upon the "fluidity" of the sample and the "settling time" allowed, than they are on the true pH of the soil sample. I have absolutely ZERO confidence in the accuracy of readings made with the Kelway meter.

I was a little skeptical about this pH meter when I ordered it. The instructions said to just insert it in the ground, but most people who review pH meters say to always add water to the soil. I didn't want to add water because our tapwater is very hard and alkaline. I do not think I would get a valid reading after adding tapwater. However, this pH meter worked fine without any added water. At first I thought I was getting more acidic readings where the ground was wetter, because the soil located away from our concrete driveway was moist and soft, while that nearby the driveway was drier and hard. Then I tested it down by our barn, where there was standing water next to a limestone gravel drive. The soil was soft and measured alkaline, as it should have. I am convinced that the meter works as promised in the instructions.