Look at emis­sions from farm dams

Tasmanian Country - - WATER MANAGEMENT -

FARM dams are a ma­jor con­trib­u­tor to cli­mate change, a study from a Deakin Univer­sity PhD stu­dent con­tends.

The study says each wa­ter­hole pro­duces about the same amount of green­house gas emis­sions as a car, due to mi­crobes in dams that re­lease car­bon diox­ide, meth­ane and ni­trous ox­ide.

How­ever, ac­cord­ing to the sci­en­tist be­hind the work, emis­sions from dams could be halved with “sim­ple” changes to farm­ing prac­tices.

Lead au­thor Quinn Ol­livier, a PhD can­di­date in Deakin’s Blue Car­bon Lab, found Vic­to­ria’s 375,000 farm dams pro­duce the equiv­a­lent amount of green­house gas emis­sions as 385,000 cars.

Mr Ol­livier’s study found dam emis­sions were caused by dis­solved ni­trate con­cen­tra­tions and were sig­nif­i­cantly higher on live­stock farms com­pared with crop­ping ar­eas.

Slash­ing ni­trate lev­els by a quar­ter by “min­imis­ing ex­cess fer­til­i­sa­tion and con­tain­ing an­i­mal ef­flu­ent”, he es­ti­mates emis­sions from some dams could be halved.

While the study found dams had one of the high­est emis­sions of all fresh­wa­ter ecosys­tems, they were not ac­counted for in gov­ern­men­tal emis­sions bud­gets.

Mr Ol­livier said that pro­vided an “enor­mous op­por­tu­nity” for gov­ern­ments to work with land­hold­ers to man­age nu­tri­ents. He said farm dams “may be emit­ting three times more car­bon into the at­mos­phere than fresh­wa­ter reser­voirs”.

“Land­hold­ers may be able to re­duce emis­sions by some­thing as sim­ple as re-plan­ta­tion of na­tive plants along dam edges, this could help to re­duce nu­tri­ents en­ter­ing the dam and there­fore the green­house gases com­ing out,” Mr Ol­livier said.

He said satel­lite net­works had only made it pos­si­ble to as­sess the dis­tri­bu­tion of farm dams in the past decade.

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