The trial aims to compare the benefits and challenges of pre-irrigation (where the site is irrigated prior to sowing and allowed to dry until soil moisture is suitable for sowing). Pre-irrigation allows timely sowing and a full moisture profile for the developing crop that should provide sufficient moisture for the crop until spring when the irrigation system restarts. However, it is not without its risks as above average autumn rainfall can delay or abort sowing altogether due to being too wet. A full soil profile going into winter can also risk waterlogging if winter rainfall is above average. Conversely, not pre-irrigating relies on rainfall for sowing and replenishing the soil profile to enable winter crop growth, exacerbated by the heavy clay soils that absorb a large proportion of small rainfall events.
The ‘Pre-irrigation’ site was pre-irrigated in early April and the site sown on May 2nd to 3 wheat varieties (slow, mid and quick maturity), 2 barley varieties (quick and mid-slow maturity), 2 canola varieties (early-mid and mid maturity) and 1 faba bean variety.
The ‘Not pre-irrigated’ site was sown on May 15th with the same crops and varieties as above after a 15mm rainfall event, but emergence has been slow due to rapid drying of the site and lack of follow-up rain until May 31st.
