Wise fer­tiliser use can save farm­ers money


With the warmer weather, farm­ers have been busy ei­ther putting fer­tiliser on their pad­docks or pre­par­ing to do so.

It’s im­por­tant to use fer­tiliser wisely to avoid un­nec­es­sary spend­ing and po­ten­tially neg­a­tive im­pacts on water qual­ity.

If farm­ers ap­ply too much fer­tiliser or ap­ply it in the wrong place or at the wrong time, this re­source can be­come a con­tam­i­nant, pol­lut­ing ground water and pro­mot­ing al­gal growth in water­ways.

Be­fore buy­ing fer­tiliser, I rec­om­mend farm­ers look at their nu­tri­ent bud­get and talk to a fer­tiliser rep­re­sen­ta­tive about the is­sues in­volved to en­sure they ap­ply only enough fer­tiliser to grow the pas­ture or crop needed. That will help min­imise im­pacts on both the eco­nomics of the farm and the sur­round­ing environment.

Im­por­tantly, if farm­ers don’t al­ready have a nu­tri­ent bud­get, they should ask their fer­tiliser rep­re­sen­ta­tive or con­sul­tant to pre­pare one for them.

There are po­ten­tial risks in­volved with fer­tiliser ap­pli­ca­tion and there are strate­gies farm­ers can use to help avoid these prob­lems. Ni­trate leach­ing Pas­ture plants need ni­tro­gen for healthy leaf growth. But N is an ex­tremely mo­bile nu­tri­ent.

If farm­ers ap­ply more ni­troge­nous fer­tiliser than plants can take up, the ex­cess N ends up leach­ing through the soil into ground water or sur­face water.

An im­por­tant rea­son for in­ef­fi­cient N cy­cling in grazed pas­tures is ni­tro­gen de­posited by the graz­ing an­i­mals, in con­cen­trated urine patches.

Farm­ers can re­duce the amount of N leach­ing from pas­ture by:

Avoid­ing fer­tiliser ap­pli­ca­tion when plant up­take of ni­tro­gen is low.

Ap­ply­ing fer­tiliser in split dress­ings.

Mak­ing sure farm dairy ef­flu­ent is ap­plied to a large enough area.

Ad­just­ing fer­tiliser pol­icy for ef­flu­ent ir­ri­gated ar­eas.

Stand­ing cows off pas­ture dur­ing wet weather and cap­tur­ing the ef­flu­ent for later ap­pli­ca­tion.

Phos­pho­rus run-off

Phos­pho­rus be­haves dif­fer­ently to N be­cause it binds with the soil and only dis­solves slowly in water over time.

This means it doesn’t read­ily leach to ground water but it can still pol­lute water­ways through sur­face run-off and soil ero­sion.

As with ni­trate leach­ing, farm­ers can re­duce the amount of P run­ning off pas­ture by en­sur­ing they don’t ap­ply phos­phate fer­tiliser when heavy rain is fore­cast. Farm­ers should also: Fol­low the NZ Fer­tiliser Man­u­fac­tur­ers’ Re­search As­so­ci­a­tion code of prac­tice for nu­tri­ent man­age­ment.

Ap­ply fer­tiliser when the grass is in a grow­ing phase.

Make sure fer­tiliser isn’t ap­plied near water­ways.

Leave a grassed buf­fer strip be­tween pad­dock and wa­ter­way.

Con­trol run-off from tracks, races, feed and stand-off pads.

To sum­marise – large nu­tri­ent sur­pluses can hurt the environment and mean a waste of farm­ers’ hard­earned cash on fer­tiliser.

Bala Tikkisetty is a sus­tain­able agri­cul­ture co­or­di­na­tor at the Waikato Re­gional Coun­cil.

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