Optimising grain yield and grazing potential of crops across Australia’s high rainfall zone: a simulation analysis. 1. Wheat

Author:

Bell, Lindsay; Lilley, Julianne; Hunt, James; Kirkegaard, John

Date of Publication:

2015-03-31

Publication Type:

Journal Article

Journal Title:

Crop & Pasture Science

Volume:

66

Issue:

4

Part:

-

Pages:

332–348

Abstract:

Interest is growing in the potential to expand cropping into Australia’s higher rainfall zone. Dual-purpose crops are suited to the longer growing seasons in these environments to provide both early grazing for livestock and later regrow to produce grain. Crop simulations were conducted to determine grain yield and grazing potential from different wheat phenology types at 13 locations across Australia’s high rainfall zone and explore how these are influenced by sowing date, nitrogen availability and crop density. At each location a factorial of four wheat cultivars representing slow-winter (e.g. Revenue), fast-winter (e.g. Wedgetail), mid-spring (e.g. Gregory) and fast-spring (e.g. Lincoln) maturity types, fortnightly sowing dates from early March to late June, four nitrogen treatments (50, 100 and 150 kg N/ha at sowing and unlimited N supply) and four crop densities (50, 100, 150 and 200 plants/m2) were simulated over 50 years using APSIM. Potential grazing days from wheat were obtained from simulating sheep grazing crops up until Zadok stage 30 (25 dry sheep equivalents (DSE)/ha). Optimal sowing dates for each maturity type at each location were matched to the flowering window when risk of frost and heat stress was lowest. Overall, we found there is significant national potential for dual-purpose use of winter wheat cultivars across Australia’s high rainfall cropping zone, with opportunities identified in all regions. Simulated mean wheat yields exceeded 6 t/ha at most locations in the HRZ, with highest mean grain yields (8-10 t/ha) in southern Victoria and lower yields (5-7 t/ha) at locations in south-west WA and central and northern NSW. Highest grazing days were from winter cultivars sown early (March to mid April) which could provide 1700-3000 DSE.days/ha of grazing across HRZ locations; this was 2-3 times higher than could be obtained from grazing spring cultivars (200-800 DSE.days/ha). Sowing date was critical to maximise both grazing and grain yield potential from winter cultivars; each week delay in sowing after 8 March reduced grazing by 200-250 DSE.days/ha and 0.45 t/ha per week delay. However, at locations with Mediterranean climates, lower frequency of early sowing opportunities before mid-April (30% of years) is likely to limit the potential to use winter cultivars. The prospects to graze shorter season spring cultivars which fit later sowing windows requires further examination. Significant potential for dual-purpose use of wheat crops was identified in south-west WA and on the northern Tablelands and slopes of NSW and southern Qld. The simulations also emphasise the importance of early sowing, sufficient N supply and sowing densities to maximise grazing potential from dual-purpose crops.

Publisher:

CSIRO Publishing

Place of Publication:

Crop and Pasture Science

Field Of Research:

Agricultural Systems Analysis and Modelling

DOI:

https://doi.org/10.1071/CP14230

Identifier:

EP143939

Publication Sub Type:

Journal article - Refereed

Language:

English

Attribution Statement:

Bell, Lindsay; Lilley, Julianne; Hunt, James; Kirkegaard, John. Optimising grain yield and grazing potential of crops across Australia’s high rainfall zone: a simulation analysis. 1. Wheat. Crop & Pasture Science. 2015; 66(4 -):332–348. https://doi.org/10.1071/CP14230