Fertiliser strategies to boost crop yield in re-engineered soil profiles

Document Type

Conference Proceeding

Publication Date

10-2024

Conference Title

Adaptive Agronomy for a Resilient Future

Place of Publication

Albany, Western Australia

Keywords

Soil re-engineering, subsoil acidity, subsoil compaction, deep placement of fertiliser, incorporation of lime

Disciplines

Agronomy and Crop Sciences | Soil Science

Abstract

Subsoil constraints such as compaction and acidity are prevalent in WA and hinder the development of deep root systems. Duplex soils, common in the region, exacerbate these challenges and lead to suboptimal yields. A field-based soil re-engineering experiment involving soil loosening and incorporation of ameliorants to a depth of 80 cm in a duplex soil profile with subsoil acidity and compaction, demonstrated that barley yields could be doubled by deep incorporation of lime, fertiliser, and clay compared to surface application of the same ameliorants. However, incorporating fertiliser to an 80 cm depth presents practical challenges to the annual replenishment of crop nutrients. To address this, two controlled environment experiments were conducted to develop fertiliser strategies for re-engineered soils based instead on surface banding and topdressing.

Results suggest that after increasing soil pH above the minimum target of 4.8 by incorporating lime and addressing soil compaction by loosening the soil, to 80 cm depth, barley yields of re-engineered soils can be maintained by surface application of inorganic fertiliser at increased rates. We found that 150 kg/ha of surface-applied N was enough to optimise barley grain yield, but higher barley protein could be achieved by applying more N. These findings help optimise fertiliser management practices of re-engineered soils, thereby contributing to the sustainability of broadacre cropping.

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