Excess anion uptake in the form of nitrate has been shown to reduce soil acidification at depth. This root-induced alkalization of rhizosphere soil can be extended to bulk soil. This study investigated ways to maximize the alkalinizing effect of calcium nitrate in reducing subsoil acidity in wheat (ET8) and canola (44Y90). A controlled environment experiment was carried out over 35 days. A Chromosol with topsoil (0-8 cm, pHCaCl25.4 and 1.5 mg Al kg-1) and subsurface soil (8-15 cm, pHCaCl2 4.8 and 2.9 mg Al kg-1) layers was used. The soil was reconstructed as 0-10 cm topsoil and 10-50 cm subsurface soil in columns (15 cm in diameter, 60 cm in height). Air-dried soils (<2 mm) were treated with three N fertilizers: 1) control, 2) urea and 3) Ca(NO3)2 with and without phosphorus fertilizer at three depths: 1) 0-10 cm, 2) 10-20 cm and 3) 20-30 cm. All N and P fertilizers were applied at 134 kg N ha-1 and 56 kg P ha-1 at sowing. Uptake of Ca(NO3)2 increased pH up to 0.2 units of bulk soil in the 0-10 cm layer compared with the urea application regardless of the placement of the treatments. Rhizosphere alkalization was greater at the depth where nitrate and P were combined compared with those with the urea treatment. We highlighted the importance of balancing nutrient supply at depth in encouraging anion uptake by plants, which enhances rhizosphere alkalization in acid subsoil.
|Title of host publication||Proceedings of the 19th Australian Agronomy Conference|
|Place of Publication||Wagga Wagga|
|Publisher||Australian Society for Agronomy|
|Number of pages||4|
|Publication status||Published - 2019|
|Event||19th Australian Agronomy Conference - Wagga Wagga Civic Theatre, Wagga Wagga, Australia|
Duration: 25 Aug 2019 → 29 Aug 2019
|Conference||19th Australian Agronomy Conference|
|Abbreviated title||Cells to Satellites|
|Period||25/08/19 → 29/08/19|
|Other||The 19th Australian Agronomy Conference will be held in Wagga Wagga, NSW from|
25 – 29 August 2019. In the heart of the Riverina, Wagga Wagga has a range of rural industries across the region. Wagga has everything to offer the agronomy conference being surrounded by a mixed farming zone with irrigation to the west and permanent pasture enterprises to the east.
The conference theme Cells to satellites highlights the integrative nature of agronomy. Each of us work across a range of disciplines to optimise crop or pasture production for productivity and profitability. We have an increasing number of tools available to increase the precision and accuracy of our work; whether it is at the “cellular” level where DNA is mapped and biochemistry is unravelled or using “satellites” for remote sensing or guidance. The opportunities for enhancing our agronomy research is boundless.