Zero till ver­sus plough

Warwick Daily News - South West Queensland Rural Weekly - - The Round-up -

FIFTY years ago, the pi­o­neers of zero and min­i­mum tillage crop­ping sys­tems had a chal­leng­ing time con­vinc­ing re­searchers and grow­ers these sys­tems had ben­e­fits over a tra­di­tional trac­tor and plough criss-cross­ing a pad­dock, but in 2018 con­ser­va­tion farm­ing meth­ods are widely ac­cepted across Aus­tralia.

This week’s guest on the Grains Re­search and De­vel­op­ment Cor­po­ra­tion pod­cast se­ries was As­so­ciate Pro­fes­sor David Free­bairn from the Cen­tre for En­gi­neer­ing in Agri­cul­ture at the Univer­sity of South­ern Queens­land.

Pro­fes­sor Free­bairn is well­known in east­ern Aus­tralia for his re­search into the im­pact of cul­ti­va­tion on soil ero­sion and re­mains the go-to ex­pert for many grow­ers when it comes to ‘real’ ad­vice on tac­tics that will im­prove soil mois­ture and on-farm prof­itabil­ity.

In this week’s en­gag­ing pod­cast he shared his in­sights into the his­tory of zero and min­i­mum tillage and the early op­po­si­tion the prac­tice faced from grow­ers and his fel­low re­searchers.

The pod­cast is part of a se­ries de­vel­oped by the GRDC to keep grow­ers and in­dus­try stake­hold­ers in­formed.

Pro­fes­sor Free­bairn grew up on a farm in New South Wales where crop­ping coun­try was cul­ti­vated and stub­ble burnt ev­ery year.

As a univer­sity grad­u­ate, his first re­search task was to as­sess the im­pact of min­imis­ing cul­ti­va­tion and re­tain­ing stub­ble on soil ero­sion. He ad­mits to think­ing ‘this won’t work’, but was amazed when rain­fall sim­u­la­tors on dif­fer­ent soils with dif­fer­ent cover re­turned the same re­sult ev­ery time – a sig­nif­i­cant re­duc­tion in run-off and ero­sion.

Pro­fes­sor Free­bairn has now re­viewed the past 50 years of re­search into zero and min­i­mum till prac­tices. Since the 1960s there have been two mind­sets: the tra­di­tional method of burn­ing stub­ble to re­duce dis­ease and make it eas­ier to plant the next crop, and the idea of leav­ing it on the sur­face to pro­tect the soil and re­tain wa­ter.

Catch­ment stud­ies look­ing at wa­ter stor­age, ero­sion and run-off showed quite early the dra­matic im­pacts of re­tain­ing stub­ble. One study showed soil loss was dra­mat­i­cally re­duced from 50 tonnes per hectare per year down to six tonnes if stub­ble was mulched and one tonne if zero tillage was im­ple­mented.

Pro­fes­sor Free­bairn said as a re­searcher, the chal­lenge was to make con­ser­va­tion farm­ing meth­ods easy for grow­ers to put into prac­tice.

“In the early days, there were no min­i­mum tillage ma­chines on the mar­ket to en­able grow­ers to plant di­rectly into stub­ble, and very few her­bi­cides. Roundup en­tered the mar­ket in 1974 but cost $20/litre, and at that time grow­ers were us­ing 1-2L/ha,” he said.

Around this time, Hec­tor Todd be­came one of the early grow­ers to ex­plore tillage and plant­ing equip­ment that could han­dle higher stub­ble loads. Ma­chin­ery eval­u­a­tion pro­grams, test­ing equip­ment im­ported from Canada and the US were ini­ti­ated in Queens­land in the mid-1970s.

Then in 1968 a study, started at War­wick, pro­vided more sup­port for con­ser­va­tion farm­ing meth­ods. It clearly showed that where there was less tillage or no tillage and stub­ble re­tained, an ex­tra 30-50mm of stored wa­ter was avail­able to the crop in most years.

“This should have con­verted to ex­tra yield but stub­ble in the sys­tem re­sulted in poorer min­er­al­i­sa­tion of ni­tro­gen at sow­ing, trans­lat­ing as lower pro­tein and lower yields,” Pro­fes­sor Free­bairn said.

So, should grow­ers fear the re­turn of cul­ti­va­tion nowa­days?

“The oc­ca­sional work­ing of a no-tillage pad­dock may trig­ger the ger­mi­na­tion of weed seeds but it won’t de­stroy 10 years of hard work,” he said.

■ Lis­ten to the pod­cast at grdc.com.au/pod­casts.

PHOTO: BRAD COL­LIS

IN­NO­VA­TION: The pi­o­neers of zero and min­i­mum tillage crop­ping sys­tems had a chal­leng­ing time con­vinc­ing grow­ers these sys­tems had ben­e­fits. IN­SET: Pro­fes­sor David Free­bairn.

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