Mr Wayne Parker1, Mr David Hall2, Mr Glen Riethmuller3, Mr Chad Reynolds1
1Department of Primary Industries and Regional Development (DPIRD) WA, Geraldton, Australia, 2DPIRD, Esperance, Australia, 3DPIRD, Merredin, Australia
Biography:
Wayne has been working in broadacre agricultural research since 2002 and loving it. Over the last ten years he has directed his focus to remediating soil constraints through both conventional and novel ways. In particular are the improvements he has been able to provide through deep ripping beyond 350 mm, the addition of lime and the use of topsoil slotting plates. The benefits from which have improved the soil, crop productive capacity and business financial position. Wayne continues to investigate improved soil amelioration techniques including the use of inert mineral mulches for improved crop yield in dry seasons.
Abstract:
Alkaline, sodic clay soil in low rainfall environments (<350mm aar) with inherent high demand for moisture provides a challenge for consistent crop establishment and yield production. Research within project DAW1902-001RTX has shown crop grain yield increases associated with in-furrow gypsum at low rates and mineral mulches. Our data showed no improvement in grain yields associated with deep tillage on sodic clay soil. These findings are based on a limited number of experiments in a limited number of locations.
We investigated, novel soil amelioration systems separately including low rates (50 – 100 kg ha-1) of gypsum in furrow, mineral mulches (2 – 4 cm) and deep tillage to 35 cm. Specifically, we aimed to test the hypotheses: 1) Crop production on sodic soil can be enhanced using chemical (gypsum) and physical (gravel mulch, ripping with a Howard Paraplow slant tine ripper) ameliorants. 2) The effects of each ameliorant are additive with respect to grain yield. 3) Gypsum in-furrow at low rates is as effective as broadcast gypsum at conventional rates
Mineral mulches were tested in 16 experiments (trial years) at sites within the Mullewa, Merredin, Ravensthorpe and Esperance Shires. The mineral mulch treatments resulted in an average yield increase of 0.59 t ha-1 yr-1 across all sites and years representing a mean yield increase of 42%. The yield differences between the mulched and unmulched treatments were significant. Low rates of gypsum in-furrow, high rates broadcast, and ripping didn’t achieve yield increases, individually or combined.
Conserving soil water through mineral mulches is more effective than gypsum or deep tillage in increasing grain yields on sodic clay soils in low rainfall environments.