Andrew Whitlock believes big gains can be made in yield while simultaneously cuttting costs by targeting crop inputs to specific soil types.

Andrew Whitlock believes big gains can be made in yield while simultaneously cuttting costs by targeting crop inputs to specific soil types.

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Make the best decisions

The Knowledge Bank

Managing by soil type rather than by paddock and understanding the variability that exists, is paying huge dividends for Precision Agriculture and its clients.


THE FOUNDER and director of Precision Agriculture Andrew Whitlock says the cornerstone of his business is simple: understanding the variability of soil types that can exist within a paddock and managing them appropriately.

“Traditionally, farmers have managed individual paddocks as individual transacts, maybe if they were really good doing something different on the swamp at the bottom of the paddock,” he said.


“We have found there are huge advantages in terms of yield boosts and a cut in inputs costs if you look beyond that and manage by soil type rather than by paddock.”

Previously with the Victorian state government as a precision agriculture agronomist, Mr Whitlock said shifting from a block farming, paddock based approach to a method respecting soil variability was common sense.

“For the majority of Australian farmers there is sufficient soil variability that having a blanket input system means the majority of the paddock is either under or over fertilised.”


Mr Whitlock said many people he spoke to were surprised at how easy it was to implement the changes.

“This does not involve state-of-the-art gear, you can do it with the equipment you have on most tractors and harvesters, the key is to make sense of the information and make it work for you.”

He said the only information he recommended farmers get that was not available from standard machinery was a pH test, which he recommended be done in conjunction with a Colwell P (phosphorus) test.

“To do a grid based pH test works out at $14 a hectare, to add a Colwell test onto that is only another $4/ha.”

“We do these tests with a clear outcome in mind. We look to investigate the variability and unlock the yield potential there.”


He said in identifying yield improvements, input savings were also found.

“We’ve found we’ve been able to cut lime rates by 30-40pc from what they would be with a blanket application, and by using variable rate, even though overall we are well back in terms of usage, the areas that need lime have received more.”

“We worked out around the Lake Bolac area, on heavier, acidic soils about 8pc of the area needed additional lime, which we were able to put out at a heavy rate of 3.5t/ha and still make savings because we could cut the rate on other parts of the farm where the soil type was different.

“In that case, 40pc of the area did not need any lime at all, so even though there were patches getting this huge lick of lime, overall we saved 52pc on liming costs.”

“When you are talking about costs of $100-120/ha for lime application it is a big saving, and well and truly pays for the cost of the pH tests.”

In terms of the P tests, he said there was a test every two hectares on the critical 0-10cm soil level.

“We don’t profess to be expert soil scientists, what we do is just provide basic information of whether you have that critical amount of P as you go to crop the paddock.

“Again, there is the opportunity to make savings in the right year as some paddocks with a good P history do not necessarily need an application if money is tight.”

He recommended the pH and Colwell P tests be done every four years.

“Amortised over a four year period the cost is very minimal, especially when you see the savings they can create, they can be massive.”


Mr Whitlock was brought up at Henty in the Riverina before shifting to Geelong, and so the business has a strong focus in the high and medium rainfall zones of the Riverina and Victoria’s Western District, served by the main office at Ballarat and one in Wagga Wagga.

“In terms of yield, I think we can do much better in our medium to high rainfall zones and PA can play a role in unlocking that yield.”

He said results from getting the right amount of nutrients and soil ameliorants on paddocks could be staggering.

“I did some work on a paddock of faba beans where a patch was under limed, and yields fell from two tonnes a hectare to 0.5t/ha, because the acidic soil had limited nodulation of the beans, it is incredible.”

As well as this there are offices in Geraldton and Toowoomba, where he said clients had slightly different focuses.

“In Western Australia there is a lot of work in terms of managing sands and nutrient leaching through PA which is showing promising results,” he said.


Mr Whitlock said his company had a philosophy of working with its clients to get the simple things right first.

“We start with the basics, getting the soil health, getting the correct lime and gypsum rates and putting in drains to ensure there are not parts of the paddock impacted by waterlogging.

“Our theory is that we address the key limiting factors first before looking at anything else.”


Mr Whitlock said a healthy soil was a buffer against seasonal extremes.

“Obviously well drained soil with good permeability is great in a wet season as it stops pooling, but conversely it also has advantages in the years where the spring cuts out as the water storage capability is that much better.”


Mr Whitlock said another platform to identify potential yield advances was through biomass mapping.

He uses biomass readings created through the use of normalised difference vegetation index (NDVI) technology to identify areas of the paddock that are under performing.

“We then go through the macro problems, like soil acidity or waterlogging and if they are ruled out you can have a look at other things, which often can be subsoil constraints not immediately apparent.

“If all the surface level things are in order, then you can start having a look at those things and testing what is down at depth in the soil profile using segmented core samples and things that might get a little more expensive.”


Mr Whitlock said PA was not an agronomy business and he saw a key role for the company as quantifying what the farmer was seeing in his paddocks.

“It is all about collecting the data so you can make the appropriate management decision.”

“We don’t work on crop varieties or disease management, it is simply about eradicating limitations in the soil.”

“By getting the relevant tests done a farmer might find out that sandy rise limits yield on 23 per cent of his paddock, even though, visually, it appears to be a smaller area.”


In terms of future trends, he said creating soil-type management zones would become more commonplace in the future.

“There will be more breaking up of crop types according to soil type parcels rather than linear paddock boundaries,” Mr Whitlock said.