Slowly, slowly trials for fertiliser efficiency
GroundCover™ Issue: 103 | Author: Clarisa Collis
For Victorian grower George Leishman, the 2012 winter cereals season at Streatham, about 80 kilometres south-west of Ballarat, had an added interest.
George commissioned trials to test whether a novel fertiliser coating from Asia could lift yields in wheat and barley at Southern Farming Systems’ (SFS) Westmere site, about 10km from where he farms 1300 hectares with his father Jamie and brother Hugh.
George initiated the research in cereals grown under Australian conditions to determine the efficacy of slow-release fertiliser technology said to be lifting rice yields in Thailand by 40 per cent.
George’s keen interest in the coating was encouraged by other research around the world that shows making urea a slow-release fertiliser can reduce nitrogen losses to the environment and improve the efficiency of plant nutrient uptake. For growers generally, this could mean more productive crops and, potentially, reduced fertiliser costs. For George specifically, it is a business prospect that could keep him in the grains industry.
The trials looked at a Thailand-made biopolymer coating. Following the harvest in December, SFS research coordinator Annieka Paridaen says the product delivered a 15 per cent yield gain in LongReach BeaufortA wheat when it was used to coat urea applied at growth stage (GS) 31. It also gave a seven per cent yield advantage in WestminsterA barley when it was applied at the same growth stage.
The coating was used at a rate of 4 kilograms/ha to coat urea, which was applied to the wheat and barley trial crops at a rate of 150kg/ha.
“The plots where the coating was used on urea in wheat and barley respectively yielded 1t/ha and 0.5t/ha more grain,” Ms Paridaen says, adding that these yields were significantly higher than the regional averages for both crops.
The biopolymer coating works by binding to fertiliser granules because it has negatively charged ions that are attracted to urea’s positively charged ions.
Brad Burgess, chief agronomist from the Thailand-based company Bio Polymer Ltd, which developed the coating, says that its main mineral component is silica, which stabilises the urea, slowing the release of nutrients to plants.
“This bond between the negatively charged coating and the positively charged urea subsequently helps to reduce nitrogen losses – through volatilisation of ammonia into the air, conversion of ammonia into nitrates by soil bacteria and leaching in wet soil conditions,” he says.
This means less nitrogen is lost to the atmosphere or washed into waterways.
This combination of reduced nitrogen losses and better nutrient uptake in plants suggests a potential for reducing fertiliser inputs while maintaining yields.
However, the preliminary SFS trials in wheat and barley did not support reports that the coating had allowed Thai farmers to halve their urea inputs without incurring yield penalties.
In the SFS trials, halving the fertiliser rate to 75kg/ha of coated urea applied at GS31 yielded slightly less wheat and barley than the control plots.
Ms Paridaen says further SFS trials in wheat, barley and canola at Westmere and Lake Bolac in 2013 will seek to clarify the optimum fertiliser rates and application times needed to maximise yield gains in different crops. The new trials will use GreenSeeker® technology to examine the amount of nitrogen made available to plants during the season and their chlorophyll composition, she says.
For George, the 2012 trial findings have a more personal interest. They provide an Australian research basis for a possible off-farm business venture that offers a solution to the problem of succession planning when a family farm is no longer large enough to support two brothers.
Apart from providing a way for the Leishmans to overcome the conundrum of who runs the family farm, George hopes the fertiliser coating might develop into a business that keeps him in the grains industry. He also hopes the enterprise has the potential to deliver broad industry benefit.
Trials of the same biopolymer coating are also scheduled to start on rice crops in NSW in September-October. The trials will be run at Jerilderie by the SunRice research and development subsidiary Rice Research Australia Pty Ltd.
Trials are also underway in maize, peanuts, rice and rubber in Europe, Indonesia, Japan, Malaysia, South Africa and South America.
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