Farms squeeze ev­ery drop from river

Pre­cise tools gauge Colo. crops’ needs as world dries up

The Morning Call - - NATION & WORLD - By Dan El­liott

GREELEY, Colo. — A drone soared over a blaz­ing hot corn­field in north­east­ern Colorado on a re­cent morn­ing, snap­ping images with an in­frared cam­era to help re­searchers de­cide how much wa­ter they would give the crops the next day.

After a brief, snaking flight above the field, the drone landed and the re­searchers re­moved a hand­ful of me­mory cards. Back at their com­put­ers, they an­a­lyzed the images for signs the corn was stressed from a lack of wa­ter.

This U.S. Depart­ment of Agri­cul­ture sta­tion out­side Greeley and other sites across the South­west are ex­per­i­ment­ing with drones, spe­cial­ized cam­eras and other tech­nol­ogy to squeeze the most out of ev­ery drop of wa­ter in the Colorado River — a vi­tal but be­lea­guered wa­ter­way that serves an es­ti­mated 40 mil­lion peo­ple.

Re­mote sen­sors mea­sure soil mois­ture and re­lay the read­ings by Wi-Fi. Cell­phone apps col­lect data from agri­cul­tural weather sta­tions and cal­cu­late how much wa­ter dif­fer­ent crops are con­sum­ing. Re­searchers de­lib­er­ately cut back on wa­ter for some crops, try­ing to get the best har­vest with the least amount of mois­ture — a prac­tice called deficit ir­ri­ga­tion.

In the fu­ture, tiny needles at­tached to plants could mea­sure how much wa­ter they con­tain and sig­nal ir­ri­ga­tion sys­tems to au­to­mat­i­cally switch on or off.

“It’s like al­most ev­ery month some­body’s com­ing up with some­thing here and there,” said Don Ack­ley, wa­ter man­age­ment su­per­vi­sor for the Coachella Valley Wa­ter Dis­trict in South­ern Cal­i­for­nia. “You al­most can’t keep up with it.”

Re­searchers and farm­ers are run­ning sim­i­lar ex­per­i­ments in arid re­gions around the world. The need is es­pe­cially press­ing in seven U.S. states that rely on the Colorado River: Ari­zona, Cal­i­for­nia, Colorado, Ne­vada, New Mex­ico, Utah and Wy­oming.

The river has plenty of wa­ter this sum­mer after an un­usu­ally snowy win­ter in the moun­tains of the U.S. West. But cli­ma­tol­o­gists warn the river’s long-term out­look is un­cer­tain at best and dire at worst, and com­pe­ti­tion for wa­ter will only in­ten­sify as the pop­u­la­tion grows and the cli­mate changes.

The World Re­sources In­sti­tute says the seven Colorado River states have some of the high­est levels of wa­ter stress in the na­tion, based on the per­cent­age of avail­able sup­plies they use in a year. New Mex­ico was the only state in the na­tion un­der ex­tremely high wa­ter stress.

The fed­eral gov­ern­ment will re­lease a closely watched pro­jec­tion Thurs­day on whether the Colorado River sys­tem has enough wa­ter to meet all the de­mands of down­stream states in fu­ture years.

The river sup­plies more than 7,000 square miles of farm­land and sup­ports a $5 bil­lion-a-year agri­cul­tural in­dus­try, in­clud­ing a sig­nif­i­cant share of the na­tion’s win­ter veg­eta­bles, ac­cord­ing to the U.S. Bu­reau of Recla­ma­tion, which man­ages most of the big dams and reser­voirs in the Western states.

The Pa­cific In­sti­tute, an en­vi­ron­men­tal group, says the river also ir­ri­gates about 700 square miles in Mex­ico.

Agri­cul­ture uses 57% to 70% of the sys­tem’s wa­ter in the U.S., re­searchers say. The prob­lem fac­ing pol­i­cy­mak­ers is how to di­vert some of that to meet the needs of grow­ing cities without dry­ing up farms, ranches and the en­vi­ron­ment.

The re­searchers’ goal is un­der­stand­ing crops, soil and weather so com­pletely that farm­ers know ex­actly when and how much to ir­ri­gate.

“We call it pre­ci­sion agri­cul­ture, pre­ci­sion ir­ri­ga­tion,” said Hui­hui Zhang, a Depart­ment of Agri­cul­ture en­gi­neer who con­ducts ex­per­i­ments at the Greeley re­search farm. “Right amount at the right time at the right lo­ca­tion.”

The Palo Verde Ir­ri­ga­tion Dis­trict in South­ern Cal­i­for­nia is try­ing deficit ir­ri­ga­tion on al­falfa, the most widely grown crop in the Colorado River Basin.

Al­falfa, which is har­vested as hay to feed horses and cat­tle, can be cut and baled sev­eral times a year in some cli­mates. The Palo Verde dis­trict is ex­per­i­ment­ing with re­duced wa­ter for the mid­sum­mer crop, which re­quires more ir­ri­ga­tion but produces lower yields.

Sen­sors placed over the test plots in­di­rectly mea­sure how much wa­ter the plants are us­ing, and the har­vested crop is weighed to de­ter­mine the yield.

“The ques­tion then be­comes, what’s the eco­nomic value of the lost crop versus the eco­nomic value of the saved wa­ter?” said Bart Fisher, a third-gen­er­a­tion farmer and a mem­ber of the ir­ri­ga­tion dis­trict board.

Blaine Car­ian, who grows grapes, lemons and dates in Coachella, Cal­i­for­nia, al­ready uses deficit ir­ri­ga­tion. He said with­hold­ing wa­ter at key times im­proves the fla­vor of his grapes by speed­ing up the pro­duc­tion of sugar.

He also uses on-farm weather sta­tions and soil mois­ture mon­i­tors, keep­ing track of the data on his cell­phone. His drip and mi­cro-spray ir­ri­ga­tion sys­tems de­liver wa­ter di­rectly to the base of a plant or its roots in­stead of sat­u­rat­ing an en­tire field.

For Car­ian and many other farm­ers, the ap­peal of tech­nol­ogy is as much about eco­nom­ics as saving wa­ter.

“The con­ser­va­tion’s just a byprod­uct. We’re get­ting bet­ter crops, and we are, in gen­eral, saving money,” he said.

But re­searchers say wa­ter­sav­ing tech­nol­ogy could de­ter­mine whether some farms can stay in busi­ness at all, es­pe­cially in Ari­zona, which faces cuts in its por­tion of Colorado River wa­ter un­der a drought con­tin­gency plan the seven states ham­mered out this year.

Drone-mounted cam­eras and yield mon­i­tors — which mea­sure the den­sity of crops like corn and wheat as they pass through har­vest­ing equip­ment — can show a farmer which land is pro­duc­tive, said Ed Martin, a pro­fes­sor and ex­ten­sion spe­cial­ist at the Univer­sity of Ari­zona.

“If we’re go­ing to take stuff out of pro­duc­tion be­cause we don’t have enough wa­ter, I think th­ese tech­nolo­gies could help iden­tify which ones you should be tak­ing out,” Martin said.

Each tech­nol­ogy has ben­e­fits and lim­its, said Ken­dall DeJonge, an­other Agri­cul­ture Depart­ment en­gi­neer who does re­search at the Greeley farm.

Soil mois­ture mon­i­tors mea­sure a sin­gle point, but a farm has a range of con­di­tions and soil types. In­frared images can spot thirsty crops, but only after they need wa­ter. Agri­cul­tural weather sta­tions pro­vide a wealth of data on the re­cent past, but they can’t pre­dict the fu­ture.

“All of th­ese things are tools in the tool­box,” DeJonge said.

DAVID ZALUBOWSKI/AP

Drones record images to help re­searchers de­cide how much wa­ter they should give the crops the next day.

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