Try drip ir­ri­ga­tion to save wa­ter

The Denver Post - - LIFE & CULTURE - By Lee Re­ich True drip Lee Re­ich, The As­so­ci­ated Press Wa­ter spreads side­ways Au­to­matic wa­ter­ing

The gar­dener who can do a thor­ough job of wa­ter­ing with hose in hand is rare in­deed.

As­sum­ing that the hose spews out about 3 gal­lons per minute in a cir­cle about 4 feet in di­am­e­ter, I roughly cal­cu­late that said gar­dener would have to stand im­mo­bile for more than two min­utes be­fore mov­ing on to the next 4foot-in-di­am­e­ter cir­cle of thirsty plants. Pretty bor­ing, if you’ve got a whole veg­etable or flower gar­den to wa­ter.

A sprin­kler is one ob­vi­ous so­lu­tion.

Even bet­ter is drip ir­ri­ga­tion, a method of ap­ply­ing wa­ter to plants slowly and over an ex­tended pe­riod of time. Drip ir­ri­ga­tion has many ben­e­fits, not the least of which is cut­ting down wa­ter use by about 60 per­cent. That wa­ter sav­ings comes from less evap­o­ra­tion and less waste; wa­ter isn’t wasted wa­ter­ing in paths or be­tween widely spaced plants. So there’s also less weed growth. Gar­den plants grow bet­ter be­cause they’re never thirsty, and dry leaves means less dis­ease.

A prim­i­tive drip ir­ri­ga­tion sys­tem could be cob­bled to­gether by run­ning wa­ter through an old gar­den hose that’s rid­dled with holes along its length and has its end plugged. The prob­lem is that less wa­ter would drip from the holes at the end than from the ones at the be­gin­ning, and higher ground would get less wa­ter than lower ground.

A drip ir­ri­ga­tion sys­tem that you pur­chase has wa­ter emit­ters en­gi­neered to of­fer a con­sis­tent, spec­i­fied out­put over wide changes in el­e­va­tion and pres­sure. They’re also made to be re­sis­tant to clog­ging or root pen­e­tra­tion. You can buy tub­ing with emit­ters in­stalled, say, 6, 12 or 18 inches apart; such tub­ing is good for wa­ter­ing whole beds. Or you can buy solid plas­tic tub­ing and punch in emit­ters wher­ever you want — ideal for widely-spaced plants.

Emit­ters, those that you plug in or those pre-in­stalled, typ­i­cally put out wa­ter at a spec­i­fied, leisurely rate of 1/4 to 4 gal­lons per hour.

For a flower bed or closely-spaced plants like car­rots, tub­ing with emit­ters al­ready in­stalled wets the whole bed. Cap­il­lary at­trac­tion into small pores in the soil draw wa­ter side­ways even as grav­ity is pulling wa­ter down­wards, so wet­ted ar­eas within the soil over­lap.

Wa­ter’s lat­eral spread de­pends on soil type, from about a foot in sandy soils to about 3 feet in clays. So in a bed, these drip­per lines could be laid out a cou­ple of feet or 6 feet apart, de­pend­ing on whether the soil is, re­spec­tively, a sand or a clay. Soils are rarely pure sand or pure clay, so ac­tual spac­ing lies some­where in be­tween.

And or­ganic mat­ter (hu­mus) in a soil helps sponge up wa­ter to in­crease lat­eral spread of the wet­ting front.

For in­di­vid­ual plants like widely spaced small shrubs and trees, fig­ure on us­ing solid tub­ing with one or more emit­ters next to each plant. Emit­ters that at­tach to the ends of thin flex­i­ble tubes are use­ful for wa­ter­ing plants in pots.

With emit­ters, tubes and a con­nect­ing hose in place, we are now back at the hose spigot. Be­fore a con­nec­tion is made to the spigot, a pres­sure re­ducer and fil­ter are needed. The pres­sure re­ducer drops the pres­sure to about 10 psi, which is all a drip sys­tem needs, and dis­penses with the need for any high pres­sure fit­tings. And a 200mi­cron fil­ter fur­ther re­duces the chances of any clog­ging.

Right at the hose spigot is the best part of a drip ir­ri­ga­tion sys­tem: the bat­tery-op­er­ated timer. This timer au­to­mat­i­cally turns the wa­ter on and off, and at about the rate that gar­den plants are us­ing wa­ter.

Of course, wa­ter use de­pends on the weather and the size and kind of plants, but a half hour of drip­ping per day is usu­ally about right. That may seem like a lot of wa­ter, but re­mem­ber, the wa­ter is just drip­ping. If a timer can turn the wa­ter on and off three times a day, set if for three 10-minute wa­ter­ings; if six times a day, set it for six 5-minute wa­ter­ings; etc.

The timer brings an im­por­tant ben­e­fit of drip ir­ri­ga­tion: It saves time. Rather than stand­ing frozen in your gar­den with a hose, you be­come free to do other things. Like smelling the flow­ers.

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