Alkaline soils: liquid out yields granular fertiliser potentially by 12,40 per cent

FARMERS ON alkaline-calcareous soils can improve grain yields by up to 40 per cent by switching to liquid fertilisers, which may provide nutrients to young crops more efficiently than granular fertiliser.

That's the key finding from a five-year research project conducted by the Crop Nutrition Group at the Minnipa Agricultural Centre, SARDI, in South Australia.

Other collaborators in the research include liquid fertiliser company Agrichem Manufacturing Industries, the Fluid Fertilizer Foundation of America, the GRDC and several broadacre farmers in SA, Victoria and WA.

The results show that cereal and pulse crop yield increases of 12-40 per cent are achievable on the alkaline-calcareous soils that are widespread across southern Australia. With wheat yields averaging around 1.5 lIha, a yield increase of say 20 per cent is worth more th an $50/ha in additional crop gross margin for these farmers, assuming a price of $ I 80/t.

"We believe Australia is poised for a big shift from granular to liquid forms of fertiliser," said Agrichem's Managing Director Frazer East. "Farmers have been successfully applying liquid or fluid fertiliser technology internationally for more than 25 years. In fact, it now represents about half the total crop fertiliser market throughout Europe and North America," he said.

Based on the latest findings from SARDI, Mr East believes there is now a strong commercial case for wider adoption of liquid fertilisers such as LMApTM (Liquid Managed Available Phosphorus) in Australia.

Liquid more economical

According to Agrichem's agronomist in SA, Andrew Lymburn, tri al results validated the company's claim that phosphorus in a liquid form was "two to three times more available to young plants than phosphorus in a granular form".

Put another way, five units of phosphorus in a liquid form will produce similar growth rates and grain yields as 15 units of phosphorus in a granular form.

"So the potential to cut cropping costs and boost yield is substantial, not to mention the transportation, storage, handling, application and environmental benefits."

Mr Lymburn said phosphorus was applied in liquid and granular forms at 10 kg P/ha in trial sites on the Eyre Peninsula. Across this region, LMAPTM consistently outperformed the granular treatments. " In the weller seasons, the increases were closer to 12 per cent but as high as 40 per cent in the drier years, when the avail ability problems assoc iated with granular phosphorus worsened."

Mr Lymburn said these latest results were consistent with those of research carried out in the late 1990s by Agrichem and initi ally involving SARDI, to assess performance based on 'equivalent costs'.

At sites in the three states, phosphorus was applied in liquid and granular forms at rates based on an equivalent cost per hectare of applied product. The liquid treatments produced yields equal to or better than granular fertiliser, which had to be given at least 50 per cent more phosphorus on a per hectare basis.

The company says seeding equipment can be adapted for liquid use. Agrichem recommended that LMAPTM be applied as a continuous band 2- 3 cm below the seed level. Alternatively, it can be injected into the soil surface using high-press ure nozzles, followed by press wheels to enhance contact with the seed.

Full details of the SARDl-led research project are published in the latest issue of the Eyre Peninsula Farming Systems Summary, sponsored by United Grower Holdings and available from Minnipa Agricultural Centre.

Program 4 Contact: Mr Andrew Lvmburn 0412478246 or toll free 1800654758