NEW Norcia full-time broadacre farmer Dave Mackie has been thinking about the need for carbon in his soils for some time and after a trial on his property this season showed an encouraging return on investment of $160-$180 per hectare, he's now set to put his thinking into action.
Growing predominantly export oaten hay as well as canola and barley, Mr Mackie recognises he removes a lot of nutrients and said carbon had been one of the only elements not being put back into soils.
Mr Mackie and his wife Marnie, who have two sons William and Jeremy, crop about 2230 hectares at their Undanooka property, plus leased land.
The Winjardie oat variety, which replaced Carrolup, and longer-season line, Kojonup, are grown for the export hay production that heads to Gilmac, while ATR Stingray and Bass varieties are used for the canola and barley programs respectively.
The typical rotation employed includes two years of hay crops followed by barley and then a canola cleaning crop.
Soils over the properties range from loamy sands through to clay loams.
Soil analysis and electro magnetic (EM) mapping surveys are helping to create paddock management zones and due to phosphorus tie-up and potassium deficiency, Mr Mackie has been "patching out'' areas with these nutrients, in addition to applying lime sand to maintain soil pH at about 5.5.
He said he had been keen to learn more about soil science and improve the organic matter level and structure of soils.
This season Mr Mackie took the opportunity to host a fully replicated trial investigating a new carbon-rich pellet with an export hay crop on marginal land comprising shallow, high-leaching, sandy gravel soil.
Developed by Carbon Ag and branded C33, the carbon pellet, which can be direct-sown through growers' seeding systems, contains 33 per cent carbon, more than 45pc organic matter and a balance of other nutrients including nitrogen, phosphorus, potassium, sulphur, copper, zinc, manganese, magnesium and calcium.
Mr Mackie used a Reefinator in the paddock to crush gravel rock to a depth of about 15 centimetres and standard fertiliser treatments included the incorporation of separate applications of lime sand at two tonnes a hectare and Muriate of Potash at 75kg/ha with a speed till machine.
The potash and the spreading of DAP with trace elements at 60kg/ha were applied to help combat the potassium and phosphorus deficiencies, while Urea KS 2:1 was spread just prior to sowing at 130kg/ha.
At seeding, MAP with trace elements was drilled at 90kg/ha, and, for the trial, the C33 carbon pellet was added at 100kg/ha and 50kg/ha in replicated treatments using the family's Morris Concept 2000 variable rate sowing rig pulled by a Fendt 936 tractor.
The trial also included the C33 treatments with half of the MAP and trace element fertiliser applied at sowing.
Other fertiliser applications across the paddock and the trial included 70 litres a hectare of UAN liquid nitrogen fertiliser at the four to five-leaf crop growth stage, followed by another 20L/ha applied later by plane.
The first UAN application also was applied with broadleaf herbicide, fungicide and insecticide to control lucerne flea and red-legged earthmite, while the second application also was applied with fungicide.
Leaf tissue testing at the trial showed increased nitrogen and phosphorus uptake with the carbon pellet treatments, the latter also suspected to be from the release of tied-up soil phosphorus.
Mr Mackie said he noticed differences in crop biomass and colour between the treatments in the trial when he got on the Massey Ferguson Hesston mower conditioner at the end of September.
The improved nutrient uptake and root development with the carbon pellet also allowed those treatments to establish more strongly and compete better against ryegrass during wetter conditions earlier in the season.
Despite receiving about 150 millimetres less rainfall than normal for the growing season, Mr Mackie's traditional fertiliser applications in the trial still achieved an average hay yield of 3.3 tonnes a hectare, however, where the C33 carbon pellet was applied at 100kg/ha, the average yield jumped to 3.94t/ha.
This represented a 16pc average yield increase.
Where the same C33 application was included with just half of the MAP and trace element fertiliser at seeding, the average hay yield of 3.79t/ha was still better than the traditional fertiliser applications.
It was a similar result where the carbon pellet was applied at 50kg/ha with half of the MAP and trace element fertiliser, achieving an average yield of 3.68t/ha.
Importantly, hay core samples also showed good colour (greenness) with some of the hay produced from the carbon-treated areas, which can help attract an extra $20/t premium in addition to yield benefits.
Collectively, the C33 treatments achieved an average return on investment of $167.50/ha compared with the traditional fertiliser applications, and before a possible added colour premium.
Further soil testing at the trial site also has shown an average 15pc increase in soil carbon levels across the C33 treatments.
Mr Mackie said they now planned to undertake soil testing across all their paddocks to help determine carbon levels and, dependent upon budgets, they could look to apply the carbon pellet at 100kg/ha with their normal fertiliser applications.
"We could do further trials on areas that are more marginal, but we could also look to apply the carbon with 50pc or 100pc of our program,'' he said.
"If growers do trials with anything on the sandplain, I think they will see good results.''
The fully replicated trial on the Mackie's property is set to continue for the next two years, similar to other carbon trials throughout the WA agricultural region in wheat, barley, canola and lupins.
The C33 pellet also will be available in granule form for growers next season, while other soil amendment products in the Carbon Ag range include the use of lime, gypsum and trace elements, as well as liquid fertilisers.
More information on the C33 pellet, trials and wider Carbon Ag product range, contact Brad Wisewould on 0429 107 919 or Jack Arundel on 0427 801 219.