Marchagee grower Clinton Hunt was busy
planning his liming program well before
seeding this year with the help of a new
GRDC-funded lime calculator spreadsheet
PHOTO: Cox Inall Communications
Marchagee grain producer Clinton Hunt has worked out that spreading lime on the yellow sandplain country that makes up 70 per cent of his property is annually delivering him a net benefit of $85 per hectare.
At an application rate of two tonnes/ha – comprising either 1t/ha of lime plus 1t/ha of dolomite or 2t/ha of lime sand – the payback period is two years.
Without liming, Clinton stands to lose about 0.1t/ha/year in cereal yields and 0.1 point per year in soil pH during the next decade in a basic rotation of wheat, canola and lupins.
This would cost an accumulated $846/ha over that period.
Clinton, who farms with his parents Ian and Helen, his sister Shannon Meyer and her husband Simon, says the family maps out a lime strategy each year, in conjunction with a specialist soil consultant, based on an extensive soil testing regime to depth across the property.
This year they have been able to use the new GRDC-funded Liebe soil amelioration (lime profit) calculator to put some dollar values on their liming program and better analyse its impact on the whole farm business for the coming season and in future years.
The Excel spreadsheet-based calculator was developed by Western Australian farm management consultancy group Farmanco, with support from the Liebe Group. It is based on earlier Department of Agriculture and Food, WA (DAFWA), acidity models, and is designed to complement existing farm budgeting software.
Clinton says it is a valuable resource for determining the extra profits, net benefits, rate of return and payback period for applying lime.
He says it should also help to improve the speed and accuracy of analysing lime requirements to reach soil pH targets at various depths or determining maintenance lime levels to counter ongoing acidification.
This function will be particularly useful for the Hunt family, who started mapping and setting up property ‘zones’ for variable-rate technology systems in 2003.
“Say you put in your surface pH target of 5.6 to 6 or a subsoil target of 5 to 5.5 for a particular zone of the farm and enter the soil type, then the lime calculator spreadsheet will spit out an application rate for lime and how much it will cost,” Clinton says.
He says this is beneficial for calculating the return and payback period for working lime into the soil at depth using mouldboard ploughing or spading.
“It takes into account all the costs of soil renovation and will provide a benefit or cost return on adopting those practices,” he says.
Owners: Clinton, Ian and Helen Hunt;
Shannon and Simon Meyer
Farm size: 8000 hectares
Enterprises: cropping, sheep, cattle
Average annual rainfall: 400 mm
Soil types: yellow sandplain
Soil pH: (CaCl2) 5 to 5.5 (surface average);
4.8 to 5 (10 to 20-centimetre depth average);
and 4.5 (20 to 30cm depth average)
Ideal crop rotation: wheat, lupins, canola (Roundup Ready®), oats, barley, cereal rye
Lime application rate: two tonnes/ha
The lime calculator can analyse the impact of a range of soil amelioration activities, including spading, mouldboard ploughing and gypsum applications.
The basic principle of the spreadsheet tool is to put a value on the benefits of liming versus expected yield decline and impact on farm cashflow and profit from not liming for a 10-year period. This has been estimated from long-term DAFWA and grower group lime trial results in the Liebe Group area.
Clinton says the incorporation of these trial results into the system gave him confidence in the robustness of the tool.
The calculator will continue to be expanded with the addition of more trial data on lime responses and expected yield declines when lime is not used.
DAFWA senior research officer Chris Gazey says soil acidity costs about $500 million annually in lost production across the wheatbelt.
He says lime application rates have increased in recent years to about one million tonnes per annum, but remain below requirements to meet recommended soil pH targets across all soil types in the region.
“We estimate 2.5 million tonnes per year of lime is needed for the next decade to recover soil pH to the targets of 5.5 in the surface and 4.8 in the subsurface layers and address ongoing soil acidification,” Mr Gazey says.
“It is essential this is targeted to the areas where it will be most effective and this means individual management plans are best.”
Mr Gazey told the Agribusiness Crop Update audience in Perth in February that it was vital growers know their soil pH profile to 30 centimetres to tailor liming strategies, analyse the economic costs of deferring liming and realise the optimal benefits from a strategic liming program.
0428 518 215
08 9661 0570
08 9690 2000
Liebe soil amelioration calculator available at www.liebegroup.org.au/lime-profit-calculator
See Chris Gazey’s 2013 Agribusiness Crop Updates Paper at www.grdc.com.au/UpdatePapers
Next: Barley powdery mildew fungicide vigilance needed in 2013
Previous: Hybrid canola lifts Mallee yields
GRDC Project Code