Article •  29/11/2023

Micromanagement of soil paying dividends at Bute

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Technology used to analyse soil types has been harnessed to improve productivity on the Venning enterprise of Barunga Grains at Bute, in the northern Yorke Peninsula of South Australia.

James Venning said they grew wheat, barley, lentils and canola across 4700 hectares on soil types that are predominantly sandy but could change dramatically across the area.

“We can have three different soil types in the space of 50 metres,” he said.  “We may have large holdings but we're micromanaging our land by zoning different soil types.  “As the machines go over different soil types, we're just doing different techniques, according to the soil."

James Venning of Barunga Grains at Bute, SA, used technology to identify different soil types and pHs to address nutrient requirements.
James Venning of Barunga Grains at Bute, SA, used technology to identify different soil types and pHs to address nutrient requirements.

He said sandy soils had traditionally been a poorer soil however they do have excellent water use efficiency.

“When it rains, the water just falls through and is stored well in the soil.  It's so reliable in the dry years and a great way to drought-proof your farm.”

He said there were multiple constraints in sandy soils, and they have been working to improve them with the use of different technologies.

“Sandy soils compact, they don't improve themselves, whereas a heavy clay will crack in a dry year and self-condition themselves.”

Mr Venning said they were zoning different areas and, in some instances, using deep ripping to break open the soils and drop organic matter behind the tines using inclusion plates.

“That holds the soil open so that organic matter will rot.”

Identifying soil pH is important in the enterprise and is done using a machine that samples and analyses soil type and logs a GPS point.

“You get a beautiful map at the end of it that has the pH of the soil,” Mr Venning said.  “The same machine measures the electronic conductivity of the soil.  Sandy soil conducts soil electricity differently to a heavy soil so it's a good way to design those paddocks knowing the soil texture."

He said different pHs have different availability of nutrients and they worked out a program to provide each soil type with the nutrients it required and could utilise.

“In soil types with a pH of 6.5 and above, the phosphorus will bind in the soil. We apply more phosphorous to these areas and then back off on the lower pH soil and not waste the fertiliser.”

In the beginning, we just moved from one area to the other, so our phosphorus spend remained the same. When the fertiliser prices started to rise, we reduced our use of phosphorous by about 20% over the whole farm."

Historically the enterprise used a blanket rate of fertiliser over the whole paddock and could see changes through the area as the crops grew.

The pH approach allows them to match soil types with nutrient needs and deficiencies and achieve a more even yield result.

“Our paddocks certainly are evening up.  If we've got a problem, we're identifying that problem and bringing it up to the mean.”

“I think behind every good grower, there's a good advisor behind the scenes. I've got a fantastic agronomist, who's not only great on soil health and plant health, but he's very good at the technology too. We work closely with him to solve these issues.”

Mr Venning said satellite imagery was used in conjunction with soil analyses and an algorithm dictates what nutrients go where.

“It's all about bang for buck. We don't want to be over-applying fertilisers. We also don't want to be under-applying fertilisers and lose productivity."

He said the program has certainly saved some fertiliser applications including an estimated 60 tonnes, or one road train of MAP (Mono-Ammonium Phosphate), at $1500 per tonne, during the high prices of recent years.

“You would never justify cutting fertiliser unless you 100% knew that you were going to be able to safely do it because you can save one dollar here on fertiliser, and it can cost you ten. The knowledge of your soils and the data to make a decision is important."

An Ipad in the tractor cab is used to direct the varied rates, with the fertiliser spread using rollers or spinners.

Cereals, lentils and canola are grown in rotation in the enterprise to help spread risk, and manage disease, and weeds.

“You’ve only got a limited amount of water and you want to maximise each crop to the water,” Mr Venning said.  “Growing canola after a lentil, rather than a canola after cereal or just having a good rotation is important."

Lentils have become an important crop with their ability to add nitrogen to the soil and act as a disease-break option.

Mr Venning said improving lentil productivity was a key goal, particularly as they sometimes struggle on sandier soil.

He said often the lentils in different parts of the paddock looked good early but battled to yield with the drier finishes.

 “We now zone the paddock to identify those areas that essentially grow high biomass levels and have adjusted the seeding rate back to 20 kilograms per hectare.

“They look poor and sparse, but they really produce."

“Another positive of doing the pH mapping was on acidic soil. Lentils do not like growing on acidic soils. They don't root very well, and they don't fix much nitrogen.  If you can get free nitrogen out of the air it's fantastic for the bottom line and fantastic for the environment.”

 “We’ve mapped the farm for pH and come across with lime. Normally two tonnes per lime, will increase the soil pH by one unit. We're trying to lift the whole farm to about a six pH and that should really help productivity on lentils."

Barunga Grains was part of the Corteva Agriscience Climate Positive program which highlights farmers doing the right thing for the environment.

Mr Venning said farming nowadays involved a social licence and there was a need to be good environmental stewards.

“You need leaders in the industry to guide you so having a company, like Corteva, looking at the new products and trying to bring things to market that change the game a little bit - it's pretty important."

He said it was important to look at the sustainability of the enterprise and keep trying to improve.

“My father always strove to grow really good crops. Whilst he didn't have the technology to take a few things a step further, he set an excellent baseline.  He drilled into me about good farm rotations. With the updated technology that's available now, we can take it further to micromanage different zones of the paddock."

“Everything you do needs to be sustainable for the future. I'd like to hand this farm on to my son or my daughter, in better condition.  If we can just continue to hand the land on to the next generation, in better nick than it was when we came across it, then I think that goes a long way to sustainability."

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