Re-engineering soils to improve the access of crop root systems to water and nutrients stored in the subsoil

Page last updated: Thursday, 21 March 2024 - 9:00am

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The aim for this project is to discover the theoretical upper limit for crop yield in water limited environments by overcoming multiple soil constraints and boosting grain yields as a result. Researchers from DPIRD are reengineering soil profiles with multiple constraints on a massive scale (to depths of 80cm) to see whether they can set new yield potential for different crops by improving crop root access to deep soil moisture and nutrients.

Start date: 01/01/2019
Finish date: 30/06/2024

Description:

This $22 million project, with co-investment from DPIRD and the Grains Research and Development Corporation (GRDC), aims to define grain yield potential in the absence of soil constraints, with a view to developing the most profitable and long-lasting strategies to manage these constraints.

It focuses on 12 million hectares of arable land covering diverse soil types – including deep sand, texture-contrast soil (duplex) and heavy sodic and boron-toxic soil – in the low to high-rainfall areas of WA where combinations of subsoil compaction, subsoil acidity, sodicity and water repellence can regularly occur.

The sites are using a combination of deep soil loosening, reconstituting profile layers and deep placement of nutrients and soil amendments, all up to 80 centimetres, to optimise water and nutrient use efficiencies of grain crops.

The sites are equipped with soil moisture probes and root architecture monitoring devices for live monitoring of soil water status and crop roots.

A total of 11 reengineering trial sites have been established including five in 2022 (Bonnie Rock, Salmon Gums, Holt Rock, Carnamah and Toolbrunup) and six in 2021 (Bolgart, Northampton, Meckering, York, Tarin Rock and Kojaneerup).

While previous research has examined single soil constraints, this research is looking at the next steps to overcome multiple constraints to achieve a new frontier in crop and water use efficiency.

Results from the 2021, 2022 and 2023 seasons:

Sandplain

Sites prepared on sandplain country at Bolgart and Northampton in 2021 were excavated to a depth of 80cm, clay was incorporated for better water holding capacity and lime, compost, and inorganic nutrients were also applied.

At the Northampton site, in 2021, the wheat yield in the best treatment was 3.3 tonnes per hectare, well above the paddock average of 0.97 t/ha. In 2022, the wheat crop yielded 3.8t/ha which is more than double the paddock average of 1.5t/ha. Unfortunately, canola crop failed to establish in the 2023 season due to a very dry start.

At the Bolgart site, in 2021, the wheat crop had poor establishment and did not respond well. But in the 2022 season, the canola crop yielded 2.8t/ha compared to the paddock average of only 0.6t/ha. In a dry season like 2023, the triticale crop yielded 1.6t/ha compared to the paddock average of 0.5t/ha.

Texture contrast soil

Four field experiments near Meckering, York, Tarin Rock and Kojaneerup had loamy duplex soils, were also excavated to a depth of 80cm and had a range of amelioration treatments applied.

At the Meckering site, in the 2021 season, the canola crop yielded 3.1t/ha, well above the paddock average of 1.4t/ha. In the 2022 season, the barley crop yield was 6.3t/ha compared to the paddock average of 3.5t/ha. In the 2023 season, the canola yield was 3.0t/ha compared to 2.0t/ha in the control.

At the site east of York, in 2021, the wheat crop yielded 5.1t/ha at the trial, compared to 3.5t/ha for the paddock average. In 2022, the canola crop yielded 3.7t/ha which is still significantly greater than the paddock average of 3.0t/ha in a record season. In the 2023 season, the wheat yield was 2.9t/ha compared to 1.4t/ha in the control.

At the Tarin Rock trial site, in 2021, the barley crop yielded 4.1t/ha, compared with a 1.4t/ha paddock average. In 2022, the canola crop unfortunately suffered severe hail damage just before harvest. In the 2023 season, the wheat yield was 3.4t/ha compared to 2.0t/ha in the control.

Heavy soil

Five new reengineering trial sites (Carnamah, Bonnie Rock, Holt Rock, Toolbrunup, and Salmon Gums) were established in the 2022 season involving physical loosening and incorporation of gypsum, different sources of carbon (compost, biochar, cereal straw), inorganic nutrients, and low pH sand for treating sodic alkaline boron toxic heavy soil.

At the Holt Rock site, in the 2022 season, the wheat crop yielded 5.8t/ha compared to the 3.2t/ha paddock average. Yield results from the remaining sites are yet to be reported. In the 2023 season, the oat crop was severely frosted and there was no yield difference between the treatments.

No significant yield response was recorded from the remaining sites. However, soil test results are showing most of the soil constraints (e.g. bulk density, clay content, organic carbon, nutrients, boron toxicity) have been improved significantly. The limited yield response on heavy soil could be mainly due to water limited environment.

Other results

An initial pilot site at Kalannie, which was established in 2018 onto sandy soils, has doubled grain yield for the past six seasons.

Funding partner:

GRDC

Project code:

DAW1902-003RTX

Contact information

Gaus Azam
+61 (0)8 9690 2159