Using silicon (Si) fertilisers to reduce water use and pest damage in crops

Even though silicon is the second most abundant element in the earths crust, most of it is bound in forms not easily available to the plant. Crop plants can benefit greatly from silicon fertilizer as its rich in plant available silicon (PAS) which can be easily absorbed by the plant. PAS has been found to reduce disease and pest attacks, enhance uptake of essential nutrients, increase water use efficiency (Schaller et al. 2021) and improve tolerance to abiotic stresses including drought and salinity. Additionally, PAS can improve water holding capacity of soils and plant available water. Specifically, Si has been shown to increase leaf water level efficiency by 32-74% in drought water treatments, however, it is still unclear if these benefits to the plant can be translated to a crop in the field (Johnson et al. 2022. If successful, silicon fertiliser could benefit a farmer greatly, especially in low rainfall zones where crops can experience significant heat and moistures stress. Additionally, silicon fertiliser could overtime reduce input costs such as spray and the rate of conventional fertilizers.

In terms of profitability for Mallee farmers, Si fertiliser could be a viable option if it enabled the farmer to put out less spray and fertiliser. For farmers to consider Si fertiliser as an option, clear benefits to yield and resilience to drought conditions need to be shown, however so far BCG does not have any results to confirm this.

The first year of the trial was 2022 where BCG tested a silicon fertiliser foliar spray on a variety of crops and found no significant effect on crop biomass or grain yield. This was the same for 2023 where there was no response when silicon was applied as a foliar and granular application. This was mainly due to the trials experiencing no heat or moisture stress during grain fill as conditions were optimal. The trial also ran in 2024, however significant frost occurred during grain fill and therefore we were unable to harvest and analyse any results. However, this year is turning out to be drier than previous years and we may see some results, especially if there is small amounts of moisture in the ground during dough development.

In conclusion, Si fertiliser may have the potential to lessen heat and moisture stress in crops, which is a major limitation for yields in the Mallee. Therefore, the aim of this project is to evaluate the potential of silicon fertilisers in enhancing crop drought resilience and explore their use in supporting the expansion of marginal farming practices in low rainfall zones.

Bibliography:

Schaller, J. et al. (2021) “Silica fertilization improved wheat performance and increased phosphorus concentrations during drought at the field scale,” Scientific Reports, 11(1), p. 20852. Available at: https://doi.org/10.1038/s41598-021-00464-7.

Johnson, S.N. et al. (2022) “Field application of silicon alleviates drought stress and improves water use efficiency in wheat,” Frontiers in Plant Science, Volume 13-2022. Available at: https://doi.org/10.3389/fpls.2022.1030620.