An EM map depicting the soil variability, soil coring and lab analysis was undertaken to determine the soil types within this paddock that were highly sodic and most likely to respond to a gypsum application. A prescription zone map is then made to apply variable rate gypsum.
Traditionally this paddock would have received a standard rate of gypsum at 2.5T/ha resulting in 296 ton being applied. However by EM mapping and ground truthing with soil analysis the gypsum use has been reduced to 173 ton a saving of 123 ton or $29/ha in addition to this higher rates of gypsum have been applied to the most sodic areas that would traditionally only have been applied with 2.5T/ha.
An EM map depicting the soil variability, this map will now form the basis for adopting variable rate gypsum.
Following from paddock mapping and soil coring, the paddock is zoned for a variable rate gypsum application including trial strips. The majority of Precision Agronomics VRT projects have embedded trials to measure gypsum responses over various soil types. This allows for long term monitoring with the aim of understanding if/ or when more gypsum may need to be applied in the future.
Visual responses in the paddock – Photos taken 21st July 2010.
Visual responses in the paddock – Photos taken 18th August 2010.
Soil cores were collected in each treatment, then weighed and dried to determine crop moisture utilization throughout the soil profile (to 40cm). The results clearly demonstrate that the higher the gypsum rate the greater the crops ability to remove moisture from throughout the profile.
Dry Matter cuts taken in September show increased biomass responses to the higher rates of gypsum.
Yield map of Field Peas from 2009 season, this clearly shows poorer yields where nil gypsum was applied.
2010 Yield response of Field Peas in relation to increased rates of gypsum.