Improved water use efficiency in no till stubble retained systems

WHY THIS PROJECT WAS NEEDED

The project was initiated to investigate the influence of row spacing on water-use efficiency (WUE) in the cropping systems typical of the Riverine Plains. The project had the principal objective of assessing the impact of row spacing on grain yield and WUE in a rotational trial that included cropping sequences of canola and wheat.

Within this over-arching objective, the underlying aims of the project were to:

• Determine if drill openers (drill or tine) influenced optimal row spacing
• Assess the impact of growing season rainfall (GSR) on the performance of crops grown under different row spacings
• Determine whether the rotation position of wheat influences the optimum row spacing
• Determine if there was an interaction between crop row spacing and subsequent in-crop agronomy.

Project outcomes

The key findings of this project were that:

• Increasing row spacing in both first and second wheat crops decreased grain yields
• In first wheat crops, there was some evidence the yield loss associated with wider rows was greater in trials where yields were higher
• In second wheat crops, the influence of row spacing on yield was smaller and not always significant
• The effect of row spacing on canola yield was highly variable in this project. When results from the four years of canola trials were analysed together, there were no significant yield differences in yield due to row spacing. However, there were significant effects in individual years.
• The narrow row spacing (22.5cm) was significantly more water efficient when compared to the wider row spacings (30cm & 37.5cm) in first and second wheat
• Row spacing produced no significant difference in the WUE of canola crops
• There was no effect of drill opener on yield of first or second wheat crops when analysed across trial years
• Canola yields were significantly higher with the disc opener.

Riverine Plains published a summary of the project findings in Between The Rows.