The aim of this project is to improve the capacity of growers to identify and manage subsurface acidity on the Northern Yorke Peninsula. Soil testing and pH mapping for acidity has become common practice in the district. However, this sampling and mapping has focused on the top 0-10 cm of soil. Recent reports and preliminary work have confirmed an acidic band of soil is often occurring at the 5-15 cm depth and beyond in certain soil types.

There are two main components to this project:

• Spatially identifying subsurface acidity by validating the relationship between soil pH and EC (electrical conductivity).
• Develop best management practices for lime amelioration to manage subsurface acidity.

• Incorporation method (deep ripping or spading) reduced plant establishment in both barley (2022) and lentil (2023) as a result of soft and uneven seedbed conditions. However, later in the season NDVI showed the crop had recovered with values similar or higher compared to the control.
• The application of lime in 2022 increased NDVI in all incorporation treatments by an average of 10% on 1st September in the following season lentils.
• In both seasons grain yields were increased by an average of 0.7 t/ha in barley and 1.03 t/ha in lentil from spading and deep ripping. However, this was not influenced by the incorporation of 10.7 t/ha Kulpara lime.
• Soil sampling one year after the trial was established generally showed lime with and without incorporation increased group E/F rhizobia levels compared to the control.
• Long-term monitoring is required to understand the movement and benefit of lime incorporation at depth.