Project Delivery: Wheatbelt NRM, Merredin and District Farm Improvement Group & MapIQ
Contact: Lizzie Von Perger
Ph: 9670 3106
Website: Wheatbelt NRM Website
Start Date: 2015 End Date: 2017
Site ID: SA00674SA1
Area (Ha): 18 ha
Surface only application of lime will be tested against incorporation via shallow leading tyne deep ripping to quantify the impact this has on speed of subsoil pH increase. Additionally, a locally sourced lime will be compared with a commercially available coastal lime source.
Many farmers are looking for a solution to subsurface soil acidity and particularly, how to speed up the process of ameliorating the acidity. Surface applied lime seems to be sufficient to arrest subsurface soil pH decline though may not increase soil pH fast enough for farmers to realise an acceptable rate of return on this investment.
The recommended rate of lime application has increased from 1 t/ha to 2 t/ha or more, due to improved production on most farms that has led to an increased rate of acidification. Additionally, best management practice currently suggests that higher rates of lime application may be required where sub-soil pH levels are also low. This higher application rate, combined with incorporation techniques, can help address acid surface and subsurface soils and can be targeted at areas that are likely to provide the highest return on investment.
Given high transport costs, establishing the greatest return on investment for different lime application rates in the central and eastern Wheatbelt is a priority. Similarly, lower quality ‘secondary carbonate’ sources that are available locally may provide a competitive return on investment due to lower transport and supply costs despite requiring higher application rates.
This trial will compare different application rates with and without incorporation (deep ripping) of commercially available lime and a locally sourced lime in a replicated strip trial design.
- Surface lime had no impact and yields of surface limed plots equalled the control plot (1.54 t/ha)
- Ripping only increased yield by 320 kg/ha (1.86 t/ha)
- Ripping + lime increased yield by an average of 470 kg/ha, an increase of 150 kg/ha on top of ripping (2.01 t/ha)
- Ripping + 13t/ha Local lime had the same yield as Ripping + 6t/ha Lime sand
- Ripping was the main driver of yield increases
- Ripping + lime gave the largest yield increases