Silicon Implant To Bolster Sugar Industry

Researchers at CSIRO Land and Water and the Bureau of Sugar Experiment Stations (BSES) say investigations into the link between low silicon and yield declines indicate it may be possible for farmers to lift yields by as much as 30-70% in affected soils by adding soluble silicon.

Scientists have understood that nitrogen, phosphorus and potassium are essential to sugarcane growth, but silicon has not until recently been regarded as a vital plant nutrient. However, after researchers tested the soil from various cane growing areas in the wet tropics, a link between low silicon and yield declines emerged.

Silicon in tropical soils declines as a result of natural climate effects, which leach it from the soil. Its levels may also be affected by certain farming practices.

Researchers tested a range of additives containing soluble silicon to see which one produced the best remedy. Among the silicon-rich substances tested was calcium silicate slag from different sources inclusing cement, plasterboard by-products, crushed rock, potassium silicate and sugar mill ash. The first trials set out to assess the different products for how well they supply silicon to a growing crop. The second set looked at the response of the crop to different rates of silicon application.

The results showed yields of millable cane increased by as much as 70% on soils treated with silicon, compared with untreated soils. In other areas, increases as high as 30% were recorded. The best results came from calcium silicate slags, which produced more cane stalks, growing to a greater height and containing more sugar.

The main task now is to work out the most cost-effective rate at which to apply silicon to farm land and to identify the cheapest local source, as the silicate slags used in the trial were imported. The assessment of local products is being undertaken in collaboration with Incitec.