Plant ‘bar­ri­ers’ help boost streams

South Waikato News - - Out & About - BALA TIKKISETTY

OPIN­ION: Build­ing bar­ri­ers has been used for thou­sands of years to pro­tect things.

This age-old prac­tice is also use­ful in the mod­ern con­text of pro­tect­ing Waikato’s wa­ter­ways.

Well-con­structed and planted ri­par­ian mar­gins be­side wa­ter bod­ies form a bar­rier that can help to keep con­tam­i­nants out.

These mar­gins - strips of land next to the wa­ter-bod­ies – can fil­ter out con­tam­i­nants such as sed­i­ment, bac­te­ria and nu­tri­ents from farm run-off, es­pe­cially those con­tained in an­i­mal dung and urine, as well as agri­cul­tural chem­i­cals.

Pathogens like gi­a­r­dia and cryp­tosporid­ium can cause wa­ter­borne dis­eases. Ni­trates and phos­phates can also cre­ate health dis­or­ders for peo­ple and stock, and con­trib­ute to al­gal growth.

Be­sides cleaner wa­ter gen­er­ally, an im­por­tant ben­e­fit of good ri­par­ian man­age­ment is im­proved stock health be­cause stock no longer get their drinking wa­ter from con­tam­i­nated streams.

Win­ter weather can place in­creased strain on the banks of farm wa­ter­ways, in­creas­ing the risk of stream bank ero­sion threat­en­ing pad­docks and af­fect­ing wa­ter qual­ity.

Some of our rivers, lakes and streams have erod­ing banks, silted beds, wa­ter weed in­fes­ta­tion and re­duced wa­ter qual­ity, as a re­sult of the way the land is used.

Land man­age­ment prac­tices – whether re­lated to farm­ing, forestry, road­ing or hor­ti­cul­ture – can cause soil ero­sion and a buildup of con­tam­i­nants into wa­ter­courses.

They in­clude stock wad­ing in wa­ter, poor cow­shed ef­flu­ent treat­ment, over­graz­ing, in­ap­pro­pri­ate fer­tiliser ap­pli­ca­tion, pug­ging and poor runoff con­trol on cul­ti­vated land, and con­struc­tion and use of roads and tracks which can all con­trib­ute to the con­tam­i­na­tion of wa­ter bod­ies. All of these prac­tices can be man­aged to re­duce the risk of gen­er­at­ing con­tam­i­nants.

A well-planted ri­par­ian mar­gin cre­ates a bar­rier be­tween the farm sys­tem and the wa­ter body, help­ing to sta­bilise banks and fil­ter out con­tam­i­nants.

Shrubs and trees with ex­ten­sive root sys­tems, which tol­er­ate moist soil con­di­tions and fre­quent silt de­posits, are ideal for stream bank ero­sion con­trol.

Bala Tikkisetty is a sus­tain­able agri­cul­ture ad­vi­sor at Waikato Re­gional Coun­cil.

Waikato Re­gional Coun­cil staff do­ing ri­par­ian plant­ing.

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