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.
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.
Clay spreading is a proven method for the amelioration of the water repellence and the improvement of productivity but it requires high initial capital investments and the outcomes can be quite variable.The aim of this trial is to identify the best combination/s of clay application rate and the subsequent method of incorporation in the topsoil (in combination with deep ripping) in order to increase the cost-effectiveness of this soil amelioration option in the northern region.Overall, tillage methods had a significant and negative effect on yield, with only the one-way plough tillage having a positive effect in comparison to the control treatment. Yields increased with increasing incorporation of subsoil clay, although the result was not statistically significant.
This trial aimed to improve understanding of the range of tillage implements and techniques available to incorporate lime into acidic soils, their respective costs and benefits. The trial was located in Badgingarra on gravelly sand. There was a significant difference at both lime rates between the “Offset + rip” tillage treatment and the other tillage treatments. There was no significant difference between the nil lime and 3 T/ha lime treatments, despite the 0-10cm and 10-20cm pH differences.
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