To assess amelioration of subsoil acidity using a range of tillage methods for incorporating surface applied lime into acidic subsoils and the impacts of tillage and lime on crop productivity.

• The trial area was seeded in June 2015 to wheat by Peter Negus, while he was seeding the surrounding paddock.  Unfortunately, the seeder ran out of seed as the trial was being sown.  The result was that there were large unseeded strips running through the trial. 
• Rainfall at the site was very poor in September and October 2015; approximately 70% below average for that period.  As a result, cereal crops on soils with low water holding capacity were badly affected, with yields well below average.
• Analysis of the harvest results (excluding plots affected at seeding) showed no significant differences, leading us to conclude that either (a) the tillage and lime treatment effects have ‘worn out’ at the site, or that (b) poor rainfall in September and October severely reduced yields, obscuring any other effects.  We believe that (b) is more likely.
• This trial will be sown to lupins in 2016.

The pH results from this trial show some interesting trends. 

The treatments with greater disturbance at depth (spade, deep rip + spade, mouldboard) tend to decrease surface pH.  This is of concern if the ‘new’ topsoil pH is acidic enough to inhibit root development. 

The treatments with greater disturbance at depth (spade, deep rip + spade, mouldboard) tend to increase midsoil pH most rapidly.  This is the effect hoped for.  The differences between treatments are generally not significant, but more intensive sampling may tease out differences.

The treatments with greater disturbance at depth (spade, deep rip + spade, mouldboard) tend to increase subsoil pH most rapidly.  This is the effect hoped for.  The differences between treatments are generally not significant, but more intensive sampling may tease out differences.