Ripping into subsoil acidity – Project overview

Improving cropping productivity

Showing the Difference - LLCI020-005

The issue

Subsoil acidity is a major constraint to crop productivity in the high rainfall zone (500-800 mm) of south-eastern Australia. Surface application of lime at a rate of 2.5t/ha is commonly used to combat topsoil acidity and lift crop yields, but what about the subsoil?

The standard surface application of lime moves so slowly through the soil profile, most of the benefit remains in the topsoil. Soil acidification is accelerated by nitrate leaching under certain crop rotations, the use of ammonium-based fertilisers and the regular removal of plant products, such as grain or hay. A major constraint to plant production on acid soils is aluminum toxicity which inhibits root growth. Smaller root systems limit nutrient and water uptake and increase plant vulnerability to stressors like insect attack, frost, hail damage, too low/high rainfall and weed competition.

The solution

In conjunction with NSW Department of Primary Industries (DPI) and the Grains Research & Development Corporation (GRDC), Holbrook Landcare Network (HLN) is participating in a long-term experiment to investigate how innovative technology can address subsoil acidity. The experiment involves the potential for deep ripping and deep placement of soil amendments to affect crop yield and health and soil chemical, physical and biological properties across a variety of regions in NSW.

Soil amendments tested include a range of inorganic amendments, such as lime, magnesium silicate, reactive phosphate rock, calcium nitrate, dolomite, gypsum; and organic amendments, like animal litters and manures, composts, lucerne pellets, crop residues.

Due to HLN's commitment to sustainable agriculture, strong community connections and membership, we are one of four cropping groups that will conduct amendment trials on farms as part of a GRDC project Innovative approaches to managing subsoil acidity in the southern grain region.

The impact

The HLN farm demonstration trials on member properties will run for three cropping seasons 2016 to 2020.

The ultimate goal is to ensure the research results are delivered to farmers to help prevent or ameliorate the risk of significant yield loss due to subsoil acidity. A series of field days will demonstrate the benefits of the most effective soil amendments and innovative technologies.

The Subsoil Acidity Project is funded by NSW DPI with financial support from GRDC and managed by NSW DPI. Project collaborators include; Charles Sturt University, La Trobe University, CSIRO, Farmlink Research, Riverine Plains Inc, Holbrook Landcare and Southern Farming Systems.

Author: Paula Sheehan