Water repellent gravelly sands may require different management to water repellent sands to improve grain yield. An increase in gravel content can increase soil organic carbon, decrease the amount (kg/ha) of soil phosphorus and potassium and potentially increase leaching of nitrate. The sandy gravels of the Badgingarra area typically have gravelly soils in the higher parts of the landscape and deep sands in the valleys which may have different soil constraints for crop growth. This transect study was completed to quantify which factors are most important for grain yield in a sandy gravel soil.
To understand the financial benefit of the many ameliorations options, it is vital to know how long the productivity gains from their implementation are likely to last. In this trial, large-scale on-farm strip trials with repeated controls using grower seeders and harvesters were applied. This trial deonstrated one-off mouldboard ploughing, rotoary spading and claying.
This trial aimed to establish how claying of sands alters crop nutrient management. Subsoil clays used for clay amendment of sands vary greatly in properties. The trial determined testing subsoils for key properties best ensures a positive response to investment in clay amendment. Two of the field experiments were studied at Badgingarra on a site with low levels of water repellence.
Three demonstration sites were established over the 4 years looking at the interaction of lime rate and cultivation in changing subsoil pH. Sites were located in Warrdarge and North Badgingarra. Spading and mouldboarding to incorporate lime are both relatively expensive methods of increasing subsoil pH and reducing non-wetting. These NACC funded demonstrations aimed to asses the effectiveness of modified one-way plough at achieving subsoil pH change.
Over the past five years considerable research has been undertaken assessing options for water repellent sands but less has been done for the gravel soils. The aim of this research is to look at soil water repellence management options for sandy gravel soils over a four year period (until December 2018). This research consisted of on-farm strip trials comprised of five different treatments for water repellence (Control, Paired row, minimal disturbance and two types of wetting agents) in combination with two cultivation treatments (modified one-way plough or no plough). The first year study showed that the adoption of a strategic tillage practice (one-way plough) provided a significant improvement in terms of crop establishment and grain yields on a moderately repellent sandy gravel.
One-off soil inversion and deep soil mixing can ameliorate repellent soils, incorporate nutrients and remove some compaction. Trials to date have shown benefits in crop productivity and yield but a more detailed understanding of the changes in soil properties and crop performance over time is required to better understand the drivers of changes in productivity and implications of buried topsoil. This trial was located in Badgingarra on pale, yellow and deep water repellent sand.
Strategic deep tillage can be used to ameliorate soil water repellence and subsoil constraints. One-way disc ploughs have a low capital cost and are relatively cheap to modify into a simple but robust tool for partial soil inversion. In this demonstration one-way disc ploughing was compared to rotary spading, a proven amelioration option for repellent sands and a number of deep ripping approaches, including some of the newer very deep rippers.
This trial was designed to assess amelioration of subsoil acidity using a range of tillage methods for incorporating surface applied lime into acidic subsoils and the impacts of tillage and lime on crop productivity. The trial site was held on deep yellow sand in Dandaragan and consisted of eight tillage treatments with three lime rates applied.
Increasing the pH of acidic subsoils in the West Midlands is necessary to increase crop water use and crop yields. A fast way of doing so is to mix lime into the subsoil; spading and mouldboarding are two common methods used in the West Midlands. Both methods are relatively expensive, so this trial aims to assess the effectiveness of a modified one-way plough at achieving subsoil pH change. This trial was located in Warradarge on deep sandy duplex soil.
This trial was conducted by Southern Dirt and aimed to improve the adoption of liming practices in the medium to high rainfall zone of Western Australia by demonstrating the economic and environmental benefits of lime application and incorporation. The trial site was located 12km north of Kojonup and was chosen for its combination of targeted soil type (forest gravel) and pH range (4.5 – 4.8 CaCl2) up to a depth of 60cm.
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