A grid soil mapping review has shown an average 30 per cent reduction in application rates for lime by using variable rate technology.
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Over 9000 hectares were mapped by Precision Agriculture during January to April this year across Southern NSW, Victoria and Tasmania with measurements taken for pH levels and phosphorous.
Precision Agriculture’s lead advisor for Victoria, Brendan Torpy, said getting the balance right between the requirements of the land and lime application rates is a complex task without the right information.
“The traditional approach to applying lime has been hit and miss as pH levels commonly vary quite significantly within and between paddocks,” he said.
“By measuring scientifically you can match lime rates to soil pH levels – using what is needed and where.
“There’s no guess work and the cost saving is often significant,” he said.
“Our results showed 27pc of land in south western Victoria did not require lime at all and under a traditional farming approach that would mean an enormous amount of overuse of lime and expense that is not necessary.”
The results do not include any benefit from yield optimisation which could be in addition to a reduction in lime use.
“There are a lot of moving factors that contribute to yield and it varies from paddock to paddock, however our anecdotal experience has been that a change to precision farming techniques has seen around a 10pc improvement in poor production zones,” Mr Torpy said.
Phosphorous measurements from the review indicated savings of 20 - 25pc on average may be achievable across the region without affecting yield.
“The results reinforce the importance of our philosophy of measuring to manage, and grid soil mapping is an integral part of this, particularly for farmers in southern Australia,” Mr Torpy said.
Grid soil mapping takes measurements of pH, phosphorus and potassium at regular intervals across a paddock to build a geographical profile of soil characteristics.
This provides a base to make lime and fertiliser decisions on a variable rate basis and pinpoint areas that could benefit from soil repair programs.
The review is the first time Precision Agriculture has aggregated its results in this way and provides a comprehensive picture of grid soil mapping techniques in southern Australia.
The company is planning another review in Spring 2016.
