Putting Water on the Ground

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DangYankee

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Here's the question - How much capacity (ft/acre or gph) would a well need to irrigate 80 acres of pasture?

Background - 6" - 8" of average rainfall per year in the desert southwest. The current well was installed to provide water for stock tanks. I'm pretty sure that the well would have to be redrilled, and I'm wondering if it would be practical to try to clear and install two 40 acre pivots. Seems like the biggest obstacle would be how much water you can draw out of the well.

Thanks for assistance :tiphat:
 
an acre is 43,560 ft2. If you wanted 1" you would need 3,630 ft3 (43,560/12in/ft).

One ft3 is approx 7 gallons, so you would need 25,410 gallons (3,630*7) to put one inch of water on one acre.

From there you can do the math on how many inches/acre and how may acres to cover. I would guess that you're going to need WAY more well than what you have. I have no idea on what it cost to put up or operate a wheel, but I would guess that it's not cheap.
 
Just for comparison:

Earlier this year we had a well drilled on our other property. Was 200' deep, installed a 10" casing, and a 7.5 HP pump with 2" dia. steel well pipe. [We could have done an 8" casing, but needed a well soon and delivery time from supplier was "weeks" not days.] The well driller had an opening and got to us within a week...VERY unusual quick service...many drillers have several months waiting perior. Total cost ran about $20K. Most of cost due to the large hole. The pump wasn't cheap either. Output on free flow was 135 gpm.

There are center pivot systems within a mile of our property. Suspect those systems are running off 3 phase power and probably deeper than 200'. Some center pivots have up to 20" hole & casing. I think most are putting out between 500 and 1000 gpm. Lot depends on the water sand you hit and the subterranian water tables.

For center pivot system, I'd recommend either using a competent "water witch" (or) using one of the companys that have seismic or similar technology. Dry (or limited water) holes are very expensive to dig...lol.
 
Engler":kkvrdf5o said:
an acre is 43,560 ft2. If you wanted 1" you would need 3,630 ft3 (43,560/12in/ft).

One ft3 is approx 7 gallons, so you would need 25,410 gallons (3,630*7) to put one inch of water on one acre.

From there you can do the math on how many inches/acre and how may acres to cover. I would guess that you're going to need WAY more well than what you have. I have no idea on what it cost to put up or operate a wheel, but I would guess that it's not cheap.
I always thought 1 inch of water per acre was 27,145 gallons.
 
I always thought 1 inch of water per acre was 27,145 gallons.[/quote]


I think you are almost right. According to Wikipedia (the "easier than trying to remember a dern thing" website) one acre foot is 325,851.4 G then divided by 12 would be 27,154.

Thanks for the comments, but I am still wondering what kind of flow would be required to run a pivot of that size. Also, how many gpm of output does a pivot of that size carry?
 
DangYankee":201innvt said:
I am still wondering what kind of flow would be required to run a pivot of that size. Also, how many gpm of output does a pivot of that size carry?

Why not check with a company that installs pivots? They just might have a vague idea.
You could also go with wheel lines, you could probably buy used stuff relatively cheaply, of course then you're married to having to move them every day or so.
 
DangYankee":1yklejhp said:
Here's the question - How much capacity (ft/acre or gph) would a well need to irrigate 80 acres of pasture?

Background - 6" - 8" of average rainfall per year in the desert southwest. The current well was installed to provide water for stock tanks. I'm pretty sure that the well would have to be redrilled, and I'm wondering if it would be practical to try to clear and install two 40 acre pivots. Seems like the biggest obstacle would be how much water you can draw out of the well.

Thanks for assistance :tiphat:

i can't justify the cost to pump the water for grazing, but if your talking alfalfa hay
 
A modern high efficiency pivot requires 5 to 6 GPM per acre irrigated if you're talking full time watering. To irrigate your 80 acres would require between 400 and 480 GPM well output. Something like K-Line or wheel lines would draw a little more water due to lower efficiency that a new pivot.

We also live in a 6-8" annual precip zone and we basically run the pivots 24/7. We have the good fortune of running on gravity mainlines so we have no pumping costs. Our pivots are not new with all the bells and whistles. We have one pivot that is 300 acres. It draws 2100 GPM. Thank God we're not pumping from 500 ft!

We find grazing these pivots much more profitable than cutting hay.
 
dun":1flex0w7 said:
DangYankee":1flex0w7 said:
I am still wondering what kind of flow would be required to run a pivot of that size. Also, how many gpm of output does a pivot of that size carry?

Why not check with a company that installs pivots? They just might have a vague idea.
You could also go with wheel lines, you could probably buy used stuff relatively cheaply, of course then you're married to having to move them every day or so.
Great idea. I sent an email and got back a request for lots of information. I told them I just wanted a basic figure to figure out what kind of investment in a well I would be talking about and got back a figure that basically called for dividing the foot acres by the amount of water you'd want to put down per the time you'd want to put it down yada yada yada. thankfully I was just trying to prove the point that you can't just put a pivot on any old well. If you are going to put in a large pivot you better have a large enough well. Seems like common sense, but sometimes there's nothing all that common about it.

Thanks for the comments.
 
Maybe you would be intersted in this piece of information from Harwell Irrigation at Springville UT

Efficiency factor 70% Amortization period 10 years
GPM required / acre 5.24 Interest rate 8.00%

Type of Unit Acres Pivot length GPM required Unit cost Cost/acre Annualized cost/acre
VALLEY CENTER PIVOT 31 651 160.26 $62,506 $2,044 $305

VALLEY CENTER PIVOT 75 1015 393.00 $85,039 $1,134 $169

VALLEY CENTER PIVOT 125 1315 653.90 $97,507 $781 $116

VALLEY CENTER PIVOT 150 1440 783.86 $108,190 $723 $108

VALLEY CENTER PIVOT 225 1769 1179.00 $138,665 $616 $92

VALLEY CENTER PIVOT 300 2040 1572.11 $177,067 $590 $88

K-Line costs are about 70-80% of pivot intallation costs/acre.

Used wheel lines are the cheapest irrigation equipment you can put in, but they have the highest labor. (other than handlines, of course)
 
We put in Kline several years ago and just love it. We pump out of a lake on the farm. For 36 A we have ten rows of pods, and use a 10 hp single phase electric motor to pump 140 gallons/minute. This puts one inch per week on the 36 A pumping 16 h per day. Electric cost is around $11/day. Can't beat it for efficiency and cost to run.

Billy
 
I have a 30 acre lake that is fed by artesian water, and some old irrigation equipment that came with my ranch when we bought it. I have a Chrysler propane industrial engine / pump and 8 inch aluminum pipe that went to a reel type irrigation system. You pull the reel out with a tractor, it has a gun type sprinkler on the end, then it is supposed to reel itself in. We tried it but it will not reel in and is way too labor intensive. I am interested in using the K line system with my propane engine / pump. It will pump something like 450 to 500 Gal / min. I would like to water 1 inch on 20 acres in 16 hours. I am not sure how the best way to pipe the water from the pump to the pasture, and how to go from an 8 inch pipe down to the smaller K line hoses. I looked at drilling a well but just can't spend that kind of money. I would really like to refurbish what I have and use it with a K line system. Any ideas or suggestions? What kind of cost?
Chris
 
CJohnson":273k4im7 said:
I have a 30 acre lake that is fed by artesian water, and some old irrigation equipment that came with my ranch when we bought it. I have a Chrysler propane industrial engine / pump and 8 inch aluminum pipe that went to a reel type irrigation system. You pull the reel out with a tractor, it has a gun type sprinkler on the end, then it is supposed to reel itself in. We tried it but it will not reel in and is way too labor intensive. I am interested in using the K line system with my propane engine / pump. It will pump something like 450 to 500 Gal / min. I would like to water 1 inch on 20 acres in 16 hours. I am not sure how the best way to pipe the water from the pump to the pasture, and how to go from an 8 inch pipe down to the smaller K line hoses. I looked at drilling a well but just can't spend that kind of money. I would really like to refurbish what I have and use it with a K line system. Any ideas or suggestions? What kind of cost?
Chris
Chris,

Where are you located and what kind of return time are you looking at with the 1"/week? What is you natural rainfall amount?
 
I think the best way to handle this is to contact a local dealer. Go to Kline's website. http://www.k-linena.com/

I'd pencil in the costs of running propane and putting in an electric motor, electricity is still far cheaper than gas.

Billy
 
MrBilly":1z1bjpsw said:
I think the best way to handle this is to contact a local dealer. Go to Kline's website. http://www.k-linena.com/

I'd pencil in the costs of running propane and putting in an electric motor, electricity is still far cheaper than gas.

Billy

Cost depends on where you're located. In Georgia you probably have electricity conveniently located close by. Another ranch in the Valley had a pivot put in a few miles above where the power lines end a couple of years ago. The estimate from the power company to run 3-phase poser up there was over $100,000. You can run a lot of propane for that kind of money.

BTW, it is another 35 miles beyond this point until power picks up on the other side.
 
Where are you located and what kind of return time are you looking at with the 1"/week? What is you natural rainfall amount?[/quote]

I am located in East Texas, natural rainfall is about 45 inches. I am not wanting to irrigate year round, mainly end of summer / early fall to be able to plant winter pasture (rye, ryegrass, oats, clovers) earlier without risk of losing the stand due to dry weather, and to get a better stand before fall rains. Also some in the summer to keep bermudagrass growing for yearlings. As far as return time, 1 inch every 1 to 2 weeks for newly planted grass and every 2-4 weeks for bermudagrass.
Chris
 
As far as electricity, 3 phase electricity would be expensive and I already have the propane engine. The other reason I thought this would be better is that I was hoping to move it to the other sides of the lake for irrigation there. Anyone using K line that can visualize this or is it not practical to move the larger pipes that go from the pump to the K line?
Chris
 
dun":2m4o77mi said:
DangYankee":2m4o77mi said:
I am still wondering what kind of flow would be required to run a pivot of that size. Also, how many gpm of output does a pivot of that size carry?

Why not check with a company that installs pivots? They just might have a vague idea.

Gee, ya think? :lol2: :lol2:
 
When an electric company gives info like this what does it mean as far as cost per week/month? I would like to put in a 50 hp motor and run it 24/7 but the cost sounds like it could be high! Can any of you help me translate this?

First 150 kWh per horsepower per month = $0.137136 per kWh,
Next 150 kWh per horsepower per month = $0.116452 per kWh
Over 300 kWh per horsepower per month = $0.075084 per kWh

would this be .13X50 hp X24X7 = $1,092 per week??

Thanks
 

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