Google "Soil Sleuth." It's cheap, and works! It's basically a notched spiral that you work into the soil. Pull it up, and feel the soil in the notches. Easy to tell if it's dry or wet.

You could make a longer one by notching a dowel.

Suzi

If you really want an instrument google "soil water content measurement" or variants of that.

If your soil lacks rocks why not try a soil probe. One that takes those small cores down 18-24 inches. Pull that out and feel the soil in your hand. I'd bet you can get pretty good at sensing the water content. I think you've said your soil is pretty sandy. That's the hardest to tell by hand. With a bit of clay it's pretty easy.

You might also keep a log of evaporation vs rainfall. Your state university or extension probably has a weather net that tracks evapotranspiration of various crops at many locations around the state. Find a crop and climate similar to yours and keep a running account of water in vs water out.

This post was edited by fruitnut on Sun, Mar 3, 13 at 12:23

thx for suggestions. my soil is rather rocky but I can probably make a tool like the "soil sleuth" out of steel that I could pound in.

fruitnut; I'll look into the evap. vs. rainfall option.

most hardware stores like Homedepot have inexpensive probes (8-10 dollars) with a readable guage (dry to wet). They actually work...but only will go about 8 inches deep. It will work good in sandy loam. When my clay gets dry it will not push through.

Your finger... And they are FREE!

You might consider gypsum blocks, see link, which are expensive up front because the block reader is a few hundred bucks plus. Once you get the reader you can read blocks located all over the place, the blocks are pretty inexpensive.

I'm lucky, my soil is 2' deep topsoil with no rocks and the soil sampling probe and examination of the cores works very well.

The only other thought that comes to mind is gravimetric determination, take a representative sample of any size you can weigh accurately and precisely and weigh it wet, then, dried. From the difference in weights, %moisture can be determined.

Hang in there in your search.

Here is a link that might be useful: Gypsum block reader

I use the digits-probe, there are ten of these high-tech gadgets hanging off your hands :-)

More seriously, is there a reason why you need to measure so deeply/accurately? I usually just push away the top inch or two and feel with finger. If its dry there its time to water.

Scott

Everyone, thx for suggestions.

re: question: " is there a reason why you need to measure so deeply/accurately? I usually just push away the top inch or two and feel with finger. If its dry there its time to water. "

My trees have grown very slowly and there has been accumulating evidence that in my sandy soil the slow growth is at least partially due to lack of adequate moisture. Hence, I was looking for a accurate way to measure.

I had a cheap one from the big box and I found it very unreliable. I was measuring moisture in potted trees and I am sure my finger did a better job. It sounds like you need a deeper probe anyway, but I would not suggest getting a cheap one.

i have mineral sand soil ...

trees grow like weeds in it ...

drainage is the key issue.. and most trees love high drainage ...

if there is a water problem.. then water more .... and mulch deeply but not close to the trunk ...

if you have true sandy soil.. you can NOT drown a tree.. it drains away ...

and all the meter is going to tell you.. is that you need to water more ... soooo .. water more ... and mulch more ...

you dont mention how old your trees are .... in my sand.. it take 2 to 3 years.. for them to really get going.. perhaps.. you just cant wait????

ken

Ken;

thx for response. my 1st (and oldest planting) is 50 apple trees I planted in spring 2009. about 50 more trees each year in 2010 (apple) and 2011 (cherry) plus 40 (cherry & apple) in 2012. trees all all mulched with wood chips after planting and mulch is refreshed annually. most all are semi dwarf except for cherry trees in 2011. all trees watered weekly their 1st year.

have yet to get one apple of original planting which is in sandiest area. Year 3 I figured out with help from harvestman that I had a nitrogen deficiency which has since been remedied. I thought I'd get apples from 2009 planting last year but frost got all my trees.

so this spring will be year 5 for original planting of semi dwarf paula red, honeycrisp, sweet 16, macintosh, and one more I can't remember.

seems slow compared to what I read for semi-dwarf. I hope to get some apples this year!!!!

I'm giving the Luster Leaf 1825 Rapitest Digital Moisture Meter a trial. I wanted something cheap to test the lawn, potted plants, trees and veggies. So far, so good. The probe is long enough to check at the feeder root level of fruit trees.

It seems to work reasonable well along with the finger test and other visual queues. The directions are easy enough to follow, but apparently some of the negative posters on Amazon didn't take the time to read them.