Response of wheat to split application of nitrogen on a leaching sandy soil

Document Type

Conference Proceeding

Publication Date

9-2006

Conference Title

Australian Society of Agronomy 13th Annual Conference 2006: Groundbreaking Stuff

Place of Publication

Perth, WA

Keywords

wheat, nitrogen leaching, sandy soils, N-fertiliser, split application, waterlogging

Disciplines

Agricultural Science | Agronomy and Crop Sciences

Abstract

Light sandy soils prevalent throughout the Western Australian wheatbelt suffer from nitrogen (N) leaching, particularly in the high rainfall zone. We evaluated the benefits of N splitting under local conditions and compared N splitting strategies namely, all at seeding vs splitting according to age, phenological development or tactical (application after 20 mm of rainfall events) using the commonly grown bread wheat varieties, Carnamah, EGA Bonnie Rock, GBA Ruby and Wyalkatchem over two years at Muresk in the central wheatbelt of Western Australia.

In 2004, despite visual differences during early crop growth, split application did not show any benefit and we attribute the lack of grain yield response to the heavy rains (25ml over two days) that followed tactical application at tillering. In 2005, splitting 120 kg N/ha according to phenological stages (30 kg applied at seeding, Z-20, Z-30, Z-50 stages) was the best splitting strategy, but its comparison with the potentially promising tactical splitting (30 kg at seeding followed by 30 kg doses after 25ml rainfall events) remained untested as the latter received only 90 kg since there were only two rainfall events that met the application criterion. The economic efficiency was evident for the tactical treatment however, as cost savings on N quantity (30 kg of N/ha) or higher gross income (about $100/ha) through greater grain yield and/or higher protein.

Based on these two years results and grower feedback, we conclude that split applications have a merit on leaching soils; splitting may be done according to age, development stage or rainfall intensity, but apparently a criterion combining tactical and crop development needs to be further investigated.

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