Tri­als look at pad­dock pH vari­ances

North East & Goulburn Murray Farmer - - NEWS -

TRIAL sites through­out the North East – in­clud­ing at Devenish, Lil­liput and Miepoll – are help­ing arm grow­ers with in­for­ma­tion on how much soil pH can vary within a pad­dock; and the acidic patches by ap­ply­ing lime at vari­able rates.

The ‘Spa­tial vari­abil­ity of soil acid­ity and re­sponse to lim­ing in cropped lands of the Vic­to­rian HRZ’ pro­ject, a GRDC in­vest­ment made in con­junc­tion with Agri­cul­ture Vic­to­ria, is in­vesti ing vari­able lime rates when the costs and re­turns vary.

Soil acid­ity is a ma­jor soil lim­i­ta­tion in many crop­ping soils of the HRZ, with many grow­ers lim­ing the whole pad­dock with one blan- ket rate to treat sur­face acid­ity.

How­ever, grow­ers are look­ing for a more eco­nom­i­cal way to do this.

Agri­cul­ture Vic­to­ria soil sci­en­tist Doug Craw­ford says the raw data avail­able to grow­ers on how vari­able soil pH can be is lim­ited.

“There is in­for­ma­tion avail­able from pre­vi­ous re­search about lime ap­pli­ca­tion re­sponses, how to test pH and the move­ment of lime through soils, but not a lot on within-pad­dock vari­abil­ity of pH,” he says.

The pro­ject is test­ing 10 pad­docks from dif­fer­ent high-rain­fall ar­eas of Vic­to­ria, in­clud­ing the North East, Gipp­s­land and Western Dis­tricts.

In each pad­dock, 100 soil cores have been taken in a grid pat­tern down to 30 cen­time­tres, which have then been cut into 10cm and the pH an­a­lysed in each 10cm in­cre­ment.

Mr Craw­ford says they have seen a con­sid­er­able range in soil pH val­ues across the pad­docks sam­pled so far.

“The most acidic pad­dock we have sam­pled was also the least vari­able, but in the less-acidic pad­docks, which had more vari­a­tion, there were patches which were strongly acidic,” he says.

“In ad­di­tion to the soil sam­pling we are also us­ing EM38, EM31 and GIS map­ping to help us bet­ter de­ter­mine the pH val­ues be­tween sam­ple points.

“We are also us­ing satel­lite im­agery to ex­am­ine the vari­a­tion in biomass across the crops and analysing grain yield data so we can map out soil pH and how it re­lates to crop growth.

“This will help us get a bet­ter han­dle on the eco­nomic ef­fects of vari­able-rate lim­ing.

“In that eco­nomic anal­y­sis we also con­sider the ex­tra cost of get­ting pH mapped and con­sider the ex­tra sav­ings from not lim­ing the parts of the pad­dock that don’t need it.”

The pro­ject will con­clude next year.

It aims to re­duce the uncer­tainty in lime de­ci­sion-mak­ing in the HRZ and en­able grow­ers to bet­ter man­age risks, both to farm

This story is reprinted from GRDC GroundCover, is­sue 137.

PHOTO: Doug Craw­ford

TRI­ALS UN­DER WAY: Acid­ity is a ma­jor lim­i­ta­tion in many crop­ping soils in the North East, with many grow­ers lim­ing the whole pad­dock with one blan­ket rate to treat sur­face acid­ity to try to over­come the con­straint. Re­search con­sid­er­ing the vari­ances are now un­der way at Devenish, Lil­liput and Miepoll.

THIS month, we take a look at some of those who work tire­lessly be­hind the scenes at the Ellinbank Re­search Cen­tre.Re­searcher Pro­file: Meaghan Dou­glas.Job ti­tle: Re­search Sci­en­tist with Agri­cul­ture Vic­to­ria.How long have you worked at Ellinbank: Four years.Qual­i­fi­ca­tions: Bach­e­lor of Science (Hon­ours).Where stud­ied: The Uni­ver­sity of Mel­bourne.Cur­rent field of re­search: Dairy cow nu­tri­tion. I am two years into a PhD in­ves­ti­gat­ing the nu­tri­tive and ru­me­nal degra­da­tion char­ac­ter­is­tics of peren­nial rye­grass pas­ture through­out the year, in or­der to for­mu­late op­ti­mal sup­ple­men­tary grain ra­tions for graz­ing dairy cows.

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