Evidence of nutrient, not soil pH, stratification in pasture soils in the Australian Capital Territory

Susan Orgill, Sally McIntosh, Belinda Hackney, Anna van Dugteren

Research output: Book chapter/Published conference paperConference paper

Abstract

There has been an increasing interest in the stratification of soil nutrients and pH, and the need to revise sampling depths to better diagnose soil surface and subsurface constraints to crop and pasture production. Twenty-three commercial paddocks were sampled in the Australian Capital Territory (ACT) to diagnose soil chemical constraints to 30 cm. There was little evidence of pH stratification, but strong evidence of phosphorus (P), sulfur (S) and potassium (K) accumulation in the surface (0-5 cm) soil. Nutrient concentrations were highest at 0-5 cm and declined significantly with depth, consistent with the trend in soil organic matter (indicated by total carbon and nitrogen concentration). Sixty six percent of paddocks had available P (0-10 cm) in excess of the critical value, while 61% were deficient in S (0-10 cm). There was no evidence of S accumulation in subsurface soil layers to 30 cm and overall 61% of paddocks were deficient in S in the 0-30 cm profile sampled. Therefore, even if S has accumulated deeper in the profile (>30 cm) it is likely to be below the root zone of most annual species until late in the growing season. Our results indicate nutrient stratification may limit pasture production more than pH stratification in the ACT.
Original languageEnglish
Title of host publicationProceedings of the 2019 Australian Agronomy Conference
Subtitle of host publicationCells to satellites
PublisherAustralian Society for Agronomy
Pages1-4
Number of pages4
Publication statusPublished - 2019

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    Orgill, S., McIntosh, S., Hackney, B., & van Dugteren, A. (2019). Evidence of nutrient, not soil pH, stratification in pasture soils in the Australian Capital Territory. In Proceedings of the 2019 Australian Agronomy Conference : Cells to satellites (pp. 1-4). Australian Society for Agronomy.