Pod­cast news: zero tillage ver­sus the plough

North East & Goulburn Murray Farmer - - NEWS -

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

Last month, a guest on the Grains Re­search and De­vel­op­ment Cor­po­ra­tion (GRDC) pod­cast se­ries, As­so­ciate Pro­fes­sor David Free­bairn from the Cen­tre for Engi­neer­ing in Agri­cul­ture at the Uni­ver­sity of South­ern Queens­land (USQ), spoke on the im­pacts of cul­ti­va­tion.

Pro­fes­sor Free­bairn is well known for his re­search into the im­pacts 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

In the pod­cast, Pro­fes­sor Free­bairn shares his in­sights into the his­tory of zero and min­i­mum tillage - and the early op­po­si­tion the prac­tice faced from grow­ers and his fel­low re­searchers.

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

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 cant re­duc­tion in runoff and ero­sion.

Prof Free­bairn has now re­viewed the past 50 years of re­search into zero and min­i­mum till prac­tices.

Since the 1960s there have been two dif­fer­ent 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 runoff showed quite early the dra­matic im­pacts of re­tain­ing stub­ble.

One study demon­strated soil loss was dra­mat­i­cally re­duced from 50 tonnes/hectare/year down to 6t/ha/year if stub­ble was mulched, and 1t/ha/year if zero tillage was im­ple­mented.

Prof 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,” he said.

“Roundup® (360 grams/litre ac­tive in­gre­di­ent) en­tered the mar­ket in 1974 but cost $20/litre, and at that time grow­ers were us­ing 1-2L/ ha.”

In 1968 a study pro­vided more sup­port for con­ser­va­tion farm­ing meth­ods, clearly show­ing 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, trans- lat­ing as lower pro­tein and lower yields,” Prof Free­bairn said.

“Then there was an ac­cu­mu­la­tion of fo­liar and root dis­eases which got in the way of max­imis­ing the im­proved wa­ter cap­ture.”

trial work, and from 1968-90 re­searchers fo­cused on breed­ing of root le­sion ne­ma­tode-re­sis­tant va­ri­eties.

In re­sponse to the is­sue of root dis­eases, the NSW De­part­ment of Agri­cul­ture de­cided to trial no tillage in tan­dem with the ro­ta­tion of other crops like sorghum and pulses, to fol­low a win­ter ce­real.

“The yield re­sponse was dra­matic,” Prof Free­bairn said.

“The ex­tra wa­ter was used by the ro­ta­tional crop, the dis­ease pres­sure was less, and yields im­proved by half a tonne to a tonne per hectare.”

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

To lis­ten to Prof Free­bairn’s pod­cast go to https://grdc.com.au/ pod­casts.

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