Neville & Glennys Turner

Investigating the benefits of applying lime and very deep ripping of sand over tight gravel soil.

• The paddock was divided into high, medium and low productivity zones.
• Soil in poor performing zone had very tight gravel at 40cm below the surface which limited root growth at depth.
• Sub soil was found to be acidic (pH in low 4's).
• I investigated the effect of very deep ripping (80cm) and applying lime on crop growth and yield.

• The trial had 2 replications and 3 control strips.
• 2T/Ha of lime was spread along half the length of all of the plots prior to ripping.
• The deep ripping was done with a dozer to 80cm.
• At a cost of $90/Ha it is not cheap.
• This trial will be monitored for a number of years to determine the economics of such a practice.
• The paddock was sown to Calingiri wheat at 70kg/Ha.

Alleviating Tight Subsoil.

• Observations made in field pits dug in September clearly showed better penetration of wheat roots into the subsoil of the ripped plots compared to the un ripped plots.

• On the deep ripped plots there was no response to applying lime. This was expected given the low rainfall during the season.
• On the un-ripped plots there was an increase in grain yield of 230kg /ha in response to applying 2T/Ha of lime.
• This returned an additional $63/Ha.
• Given that the lime cost $70/Ha, it almost paid for the lime in the first season.

• Deep ripping to a depth of 80cm to alleviate a tight subsoil resulted in a 470kg response in wheat yield in the dry season of 2002.
• This increased yield netted an additional $49/Ha after paying for the cost of deep ripping.
• Applying lime to unripped plots almost paid for the cost of liming in the first season.
• This trial site will be monitored to evaluate the ongoing benefit of lime and deep ripping.