Re­con­sid­er­ing the so­lu­tions to farm pol­lu­tion

Nelson Mail - - Front Page - Skara Bohny [email protected]

Just be­cause ni­tro­gen is leach­ing into wa­ter­ways from farms doesn’t nec­es­sar­ily mean that in­di­vid­ual farm­ers are to blame, a river health ex­pert says.

Di­rec­tor of the Grif­fith Univer­sity’s Aus­tralian Rivers In­sti­tute, Stuart Bunn, said many places in New Zealand and Aus­tralia with river health is­sues were deal­ing with the fall­out from colo­nial-era de­ci­sions.

‘‘When you look at ru­ral places, they’re deal­ing with legacy is­sues, things they in­her­ited from gen­er­a­tions ago,’’ Bunn said.

‘‘You can’t just say, ‘You’re re­spon­si­ble, you’re on that farm, that’s where the ni­tro­gen is com­ing from’. [The farmer] didn’t nec­es­sar­ily cause that.’’

Bunn, who was vis­it­ing Nel­son’s Cawthron In­sti­tute this week, said the in­dis­crim­i­nate clear­ing of land by Euro­pean set­tlers, of­ten start­ing from the rivers, which were used for trans­port, laid the ground­work for many of the prob­lems that farm­ers, foresters and rivers were deal­ing with to­day.

How­ever, Vic­to­ria Univer­sity fresh­wa­ter ecol­o­gist Mike Joy said much of New Zealand’s poor river health was due to more re­cent dairy in­ten­si­fi­ca­tion.

‘‘Com­ing from Aus­tralia, and cer­tainly from north­ern Aus­tralia, the changes that hap­pened there weren’t any­where near as sud­den and re­cent and in­tense [as in New Zealand]. We had this re­ally, re­ally re­cent in­ten­si­fi­ca­tion, and a mas­sive in­crease in ir­ri­ga­tion to al­low that in­ten­si­fi­ca­tion,’’ he said.

‘‘Stock­ing rates have gone up dras­ti­cally in the last 20 to 30 years . . . so you have to add lots of ni­tro­gen fer­tiliser, which is made out of fos­sil fuel. And a lit­tle bit of the ni­tro­gen fer­tiliser goes into the milk, but most of it, 75 per cent or more, goes out of the cow through urine.

‘‘That is kind of ni­trate fer­tiliser in that urine at an in­ten­sity that the grass can’t use, be­cause it’s just too much of it in a small area. So it goes past the roots of the grass and into the ground­wa­ter or into the gravel, which makes its way into aquifers and rivers.’’

Joy said that while ri­par­ian plant­ing helped to re­duce sed­i­ment runoff and over-land con­tam­i­nants like E.coli get­ting into rivers, it wasn’t enough to re­duce the un­der­ground leach­ing of ni­tro­gen-based fer­tilis­ers into wa­ter­ways.

He said the cur­rent in­ten­sity of dairy­ing was the is­sue, and at that level, any mit­i­ga­tion other than re­duc­ing in­ten­si­fi­ca­tion would have a min­i­mal im­pact.

Bunn said that whether the mit­i­ga­tion was done by re­duc­ing stock­ing rates or by fenc­ing and plant­ing around wa­ter­ways, there was a need for ‘‘much more clever ways to in­cen­tivise that ac­tion’’.

He said there was a mix of foresters and farm­ers who were tak­ing steps to mit­i­gate their im­pact on rivers, but ‘‘if you’re re­ly­ing on in­di­vid­ual land own­ers to do a pub­lic ser­vice by pro­tect­ing their patch, we’ve got to do more than that’’.

He said one way was to cre­ate a mar­ket for en­vi­ron­men­tal ac­tion, some­thing that was not nec­es­sar­ily as dif­fi­cult as peo­ple might think.

‘‘You can pay a farmer to plant more trees . . . we need to think beyond that: what about ni­tro­gen? What about sed­i­ment? Could we mon­e­tise them? We know ex­actly what the cost of water treat­ment is with and without good water qual­ity.’’

Bunn said peo­ple or or­gan­i­sa­tions down­stream from pol­luters were usu­ally left ad­dress­ing the symp­toms of up­stream prob­lems, but those meth­ods were po­ten­tially more ex­pen­sive than an en­vi­ron­men­tally-fo­cused pre­ven­tive mea­sure at the source.

‘‘You might spend $1 bil­lion build­ing a water treat­ment plant. Or what if you spend $500,000 re­build­ing a wet­land and get­ting the same re­duc­tion? What if you could achieve that by work­ing up­stream?’’

He said ac­tiv­i­ties like wet­lands restora­tion and ri­par­ian plant­ing were nat­u­ral and some­times less ex­pen­sive ways of ei­ther pre­vent­ing or re­mov­ing ni­tro­gen and sed­i­ment buildup in fresh­wa­ter.

‘‘If you asked peo­ple how much they value the rivers and seas around here, they would rank it re­ally highly . . . but when it comes to ‘How much would you spend on it?’, peo­ple value it but don’t want to pay. In­creas­ingly, we’re . . . look­ing to bet­ter ex­plain to peo­ple why it’s valu­able.

‘‘Fresh­wa­ter sys­tems, their bio­di­ver­sity is de­clin­ing at twice the rate of bio­di­ver­sity on land or in the sea. Since 1970, we’ve lost 80 per cent of our fresh­wa­ter population­s.’’

He said many peo­ple thought of ef­forts to pro­tect the en­vi­ron­ment as ex­pen­sive and dif­fi­cult, but it was pos­si­ble for en­vi­ron­men­tal pro­tec­tion to be eco­nom­i­cally ef­fi­cient and even prof­itable, with the right re­search to back it up.

MUR­RAY WIL­SON/STUFF

River health and the dairy in­dus­try are strongly linked, but cur­rent dairy farm­ers aren’t nec­es­sar­ily blame­wor­thy, says an Aus­tralian sci­en­tist.

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