GRAIN growers keen to embrace zero-till cropping systems may find themselves with seedling-emergence problems if they just swap knife points for discs, a researcher has warned.
Birchip Cropping Group and University of Melbourne researcher Dr Michael Walsh said stubble pinning and pre-emergent herbicide damage resulted in lower seedling emergence and reduced biomass at flowering during trials of disc sowing systems at Nhill last year.
But the dry finish to the season meant there was no difference in grain yields between crops sown with knife points and those sown with discs.
Dr Walsh said the no-till system, using knife points and press wheels in a single pass at sowing, was highly successful.
"It has revolutionised crop production across Australia by retaining stubble, enhancing moisture retention and reducing erosion," he said.
"The next phase in the development of more conservative and sustainable farming systems for the Wimmera and Mallee is likely to be a progression from no-till to zero-till cropping systems.
"Zero-till discs will further reduce soil disturbance, but require a new approach to weed control, pest management, fertiliser use, row spacing and residue management."
Dr Walsh compared the performance of three seeding systems and three pre-emergent herbicides on wyalkatchem wheat sown into ungrazed wheat stubble on two soil types.
The seed was sown by knife point press wheel at 7.5km/h, single disc at 10.5km/h and triple disc at 10.5km/h, with Triflur X, Boxer Gold and Sakura applied immediately before sowing and one control plot left untreated.
In the control plot, crop emergence was best under the tine sowing system and reduced by 8-35 per cent under the disc systems.
Dr Walsh said this was attributed to the pinning of moist stubble beneath the seed during sowing.
Crop establishment was reduced 52-74 per cent using Triflur and a single disc, while the triple disc threw more soil out of the furrow and reduced the level of damage.
