Summer and early season rainfall has prompted early sowing in many parts of the WA wheatbelt.

Sowing earlier than the traditional May break makes use of summer moisture and may mean higher yields – if the right varieties are used. Longer growing varieties sown early (March/April) have demonstrated higher yields compared with typical spring wheats sown in the traditional window (May/June).

A CSBP trial at Dalwallinu is investigating the yield potential of three long season wheat varieties that are largely untried in the northern WA wheatbelt. Using multiple N rates on each variety (Table 1) the trial aims to provide information on the varieties, including: 
• Nitrogen requirements including rate and timing.
• The different development and flowering times of each variety.
• Local grain yield and protein.

A better understanding of how long season varieties perform in the northern wheatbelt and how to manage them may encourage growers to plant them in future seasons. 

Trial details

The three varieties were sown on 8 April 2021 at a seed rate of 53 kg/ha:
• Illabo (AGT) winter wheat (APW/AH) a dual-purpose wheat for grazing and grain production. 
• Denison (AGT) a very long season spring wheat (APW).
• Rockstar (Intergrain) a medium-long season spring wheat (APW/AHN).

Table 1. Trial fertiliser treatments and rates

Basal 20 kg P/ha

Results and observations to date

Nitrogen
Nitrogen has been a key driver of early crop growth in all three varieties. Tissue tests five weeks after seeding identified marginal N status in both the 50 and 100 Flexi-N (FN) banded treatments.

The higher N plots showed increased biomass, tiller numbers and crop health (NDVI) (Figure 1). By June, at the 96N rate, plots with 100 Flexi-N (FN) banded at seeding had higher NDVI readings than plots with 50FN (Figure 2) suggesting more N earlier in the season is necessary to maximise early crop growth.