[quote]Model guidance is in unusually good agreement for a potentially
significant storm early next week, given the energy associated
with this system is still over halfway across the Pacific Ocean.
Mid and high level moisture ahead of the trough will likely
overspread Southwest California by Monday in the form of mid and
high level clouds and possibly drizzle or light rain. Widespread
and possibly significant rain and mountain snow is likely by
Tuesday along and ahead of what currently looks to be a well
organized cold front. This system may be the first of several, as
second storm system may bring additional rain and mountain snow by
the middle of next week. [/quote]
Just looking at upper level tempsā¦this looks like a cold storm. Lower elevation snow iād imagine.
UNCEā¦North Las Vegas orchard ā¦iāve seen some Youtube videos on that place and they use a ton of mulch with their wide selection of fruit trees (peaches/pluots/etc)ā¦ Not sure how different your soil is to Vegas soil?
Thatās what we do. I was lucky- when I bought my property I really didnāt know what the best soil would be for fruit trees. I knew a lot more about growing vegetables than fruit in the East at the time. I assumed that the richer the soil the better for growing all things but discovered that my water repelling silt loam works very well for both quality fruit and for bare root tree production (easy digging once I get most of the rocks out).
quote=āRichard, post:665, topic:3613ā]
Core samples and electronic water depth meters.
There are plenty of GeoTech firms out here, some in agriculture and a few of which employ former students. For my better-healed customers I hired them to come out for a soil survey. Depending on their needs it would be $350 to $1250 (circa 2010). Theyād bring a walk behind auger and take 1 to 2 meter deep core samples. If a water moisture study had not been done in the area in the past theyād also insert 4-6 1-meter sensors with at least one in an unirrigated location.
But the water holding capacity of the soil is only part of the story- how do you monitor the moisture content of your soil that your fruit trees can reach at any given time and determine the actual needs of your trees? Knowledge of capacity is useless if you arenāt measuring evaporation and transpiration. Most of us accomplish both by actually digging and testing the soil with our hands to get a ball park of moisture level- some of us simply wait until trees show some signs of water stress in the middle of the day- I assume you know there are more accurate tests.
You often proscribe here quantities of water that seem excessive to me to manage an orchard but seem confident that your conditions require it. Iām still trying to figure out how you have determined your water needs and your explanation seems incomplete. Almost like a politician explaining health care.
Incidentally, I donāt think mulch effects moisture levels in soils as much as is being suggested here. Iāve read, that the first few inches of soil functions like mulch as far as protecting soil beneath from evaporation. Mulch can store water and some water is actually created as it breaks down, but it canāt stop transpiration.
This is well-established at many locations in southern California, including my present home. The published data matches the data Iāve collected with my Davis sensor.
LOL!
I agree. However, it is also necessary as soil evaporation is a big problem here with a constant breeze and humidity typically below 50%.
You explanations only add to my confusion- is this how you communicate with your clients- they must believe you are genius! What I understand about irrigation is that farmers monitor the moisture level of their soil primarily by measuring the moisture level of their soil. Iāve never heard of a Davis sensor and Iām sure most on this forum have not either.
Come on Richard, try a little harder. Pretend you are talking to an 8 year old and explain in easy to understand language how you determine how much water your fruit trees need at any given time during the season, with all the variables in play (including the amount of water actually needed by the trees at any given point in fruit development).
Iām trying to learn something here, and Iām sure others are as well. When I look up university specs on monitoring irrigation needs, what I find doesnāt seem to jibe with what you are writing, but then, Iām just a layman.
But that doesnāt say anything about how the instrument works.
The methods Iāve used are taking soil cores, drying them, and comparing % water content to tables developed for each soil horizon. Also a soil neutron probe which is lowered down access tubes usually 6ft into the soil. Lastly we had a weighing lysimeter. This is the gold standard but very expensive and limited by crop choice, ie itās only helpful for the crop planted in the lysimeter at the current time.
There are new instruments that can be buried like the Davis probe but I never used them. They were under development when I retired.
Now days for crops like irrigated corn in the Texas panhandle the research and extension programs calculate water use by the crop each day. Use that and local rainfall to determine the irrigation requirement.
Thatās an electrical resistance block. It measures the electrical conductivity of the soil. The drier the soil the lower the conductivity. But itās not considered accurate enough for serious needs like watering of commercial crops. It was never even considered for research purposes either by the USDA or Texas A&M.
Comparing the pictures from the web of a Davis Soil Moisture Sensor and the pic in the website I posted, they look the same. Also, in this page (http://www.fondriest.com/davis-soil-moisture-sensor.htm), they mention the Davis Sensor works through measuring soil resistance, so I assume theyāre the same but maybe Iām off.
Yes itās the resistance to passage of an electrical current. But the instrument isnāt all that representative of the actual undisturbed soil. There are many possible issues. In soils that have a hardpan or even just dense soil horizons placing the instrument disturbes the soil. That can alter both penetration and passage of water but also crop roots. That means the instrument isnāt measuring conditions representative of the actual soil/crop.
The soils in the Texas panhandle often had a dense subsoil. Digging up and mixing together the upper 6ft of the soil considerably increased water penetration, root penetration, and yield of dryland crops. Even when that involved mixing the topsoil in with the clay and caliche below.
You were referring to measuring transpiration and so I was referring to the Davis sensor for that purpose, the leaf moisture sensor.
Soils and microclimates within 10 miles of the coast vary a lot here ā even within a half mile of each other ā and sometimes within the same property.
My general approach is to first measure the physical structure of the soils (core samples). When encountering soils of unknown seasonal behavior I then rent the services of a GeoTech or Ag firm to measure them from spring though fall in the given microclimate. Some of these firms have been doing this for nearly a century and can give you the data of your location for the cost of a consultation.
Once you know the rates of drying and wetting you can proceed with an irrigation plan. I understand that east of the Rockies overwatering is a chief concern. I have the opposite concern: I am sitting on several hundred feet of caleche of modest density ā a former sea bench. It is sands with Calcium and other minerals and no carbon. When it dries out it is difficult to re-wet. So yes, there is humic acid in my fertigation program.
Thank you Richard, FN and Brad. I had no idea there was an instrument that tested water status by way of the leaves. The electoral resistance instrument I had read about and I actually own one of a type as part of a fancy pH meter I have. I never use it because after a lifetime in a huge range of soil types I feel confident about getting an adequate ballpark feel for the moisture level of a soil.
Iām old fashioned, perhaps because Iām a dry farmer in a region where if I can get water to the trees, cost is not in issue. However, it amazes me how poor a job the lawn irrigation companies do here- they seem to run the water heads on a schedule that makes no allowance for rain or shady spots on properties- absolutely no use of moisture sensors. I prefer managing an orchard that receives no supplementary water to this. Itās very annoying to be tending an orchard a day after a 2"+ rain and suddenly have the lawn sprinklers come on all around you when the soil is already mud.
