[Market-farming] How do you irrigate?

Road's End Farm organic87 at frontiernet.net
Mon Mar 15 12:30:23 EDT 2010


On Mar 15, 2010, at 8:13 AM, Garth & Kim Travis wrote:

> Greetings,
> I am confused, it has a well for the house and is only 7 acres. So why
> would you need another well? We have 20 acres and 1 well, that does  
> the
> job. You probably just need to run some pipes.
>

> Alliums wrote:
>>
>> I’m looking at a 7 acre property that doesn’t have a water source
>> (unusual in Southeastern PA). It has a well for the house, but  
>> nothing
>> else. Should we dig another well for irrigation? Should we gather the
>> water that flows to the bottom of the property into a pond?


There may not be anywhere near enough water coming into the house well  
to irrigate 7 acres. There may not even be enough water coming into  
the house well to irrigate a kitchen garden for the household. I have  
neighbors slightly downhill from me who have three wells, and during  
long dry spells they need to have water hauled in so they can take a  
shower. My well will supply the household, but produces only about ten  
gallons per minute when the weather has been wet enough so the  
groundwater supply is good, and much less than that if the weather has  
been dry for some time; this in an area where some others less than a  
mile away have more than enough water to run 100 cow dairies and  
irrigate large market gardens in addition -- and there is a huge lake  
less than a mile from me. It all depends on the way the water is  
moving underground, which, around here, is highly variable.

It's not possible, in this area, to just keep drilling deeper: there  
are salt beds as part of the bedrock layers, and drilling too deep is  
extremely likely to bring up water far too salty to either drink or  
irrigate with.

In addition, not all properties will produce a good irrigation pond.  
If the soil's not deep enough or not otherwise suitable, it may not be  
possible to build a deep enough pond, or it may only be possible with  
the use of very expensive lining techniques. If there's not enough  
water on the property to keep the pond full, and there is no  
underground spring to fill it, the pond may run out during long dry  
spells (this is the situation that I'm dealing with). What looks like  
a lot of water at the bottom of the property in March may not be  
anywhere near enough water in a dry August.

Having said all that: the property in question may have lots of water  
(maybe you've got a well as good as Kim's!); but you do need to find  
out. Your county Soils and Water should be able to tell you whether  
the property is likely to produce a good irrigation pond, and also  
something about how much water you're likely to be able to get from  
the well; also whether drilling additional wells will accomplish  
anything other than maybe dividing the available water between them,  
and/or messing up your neighbors' water supply. I'd double check that  
with well drillers and pond builders who have both significant  
experience in the area and good reputations. It should also be  
possible to test the existing well for output, although again, the  
output may or may not be consistent through the year; so bear in mind  
that you'll be testing it at a time when the available water is  
probably highest. -- You can, and should, do all of this before buying  
the property; either do it before you put in a bid, or put in a bid  
that specifically states it's contingent on your being able to find as  
much water as you need.

-- One acre-inch of water is 27,154 gallons. If you want to be able to  
irrigate all 7 acres at once (which you might not, as some of it might  
be in cover crop or fallow rotation at any given time), you'd need  
about 190,000 gallons per week, or about 20 gallons per minute from a  
source capable of producing that 24/7 for possibly several weeks  
straight (many sources that will supply 20 gallons a minute can't keep  
up that rate all week, or even all day). You could reduce the amount  
needed by using drip irrigation, laid out so you only irrigate the  
actual root zone of the crop and not paths or areas between beds or  
rows.

Oh yes: also get the household well water tested for quality! Coliform  
and lead at a minimum, and check with Soils and Water as to what else  
you need to check for -- salts, nitrates, and/or atrazine, for  
instance, may be an issue in some locations. It's astonishing what's  
in some household wells without the owners being aware of it -- even  
if they're roaringly healthy, that may be because their systems have  
adjusted to the local bacteria. Some problems with well water quality  
may be easily repairable -- there might just be a surface crack in the  
casing -- but others aren't.

-- Rivka; Finger Lakes NY, Zone 5 mostly
Fresh-market organic produce, small scale



-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.ibiblio.org/pipermail/market-farming/attachments/20100315/7e584473/attachment.html 


More information about the Market-farming mailing list