Erin Cahill (agVivo)
Bindi Isbister (Precision Agriculture)
David Isbister (Homewood Farms)
|Contributor||West Midlands Group|
Demonstrate variable rate technology on farm and how it can be applied to manage fertiliser use and to minimise nutrient enrichment or depletion that leads to poor soil health.
This year there was no big benefit from variable rate fertilizer in relation to yield. This is not unexpected given the dry season.
This trial gives some confidence that cutting fertilizer in particular P back on the low zone did not impact yield and had the best gross margin, therefore is a good strategy to reduce costs on the lower performing parts of the paddocks. This is consistent with current DAFWA and GRDC research findings that less phosphorus can be applied on soils with good P history without penalizing yield. Similarly it demonstrated the potential to reduce rates on the higher production zones depending on the season as tissue tests indicated adequate nitrogen just prior to the late N application. It is likely there was also more nitrogen available as a result of ripping increasing nitrogen mineralization and plant root access to water and nutrients. Reducing N applied after ripping is a recommended strategy to reduce the risk of the producing high biomass and the crop haying off early with a dry finish.
The estimated yield potential of the zones was not reached with the high zone about 1.5 t/ha below potential. This is consistent with farm observations that found there was a penalty of about 1 t/ha for crops sown later than 7 days from the 22nd May crops in this dry season.
High resolution six meter imagery was found to be very useful to identify management issues and map non-wetting soils, particularly the early July image which highlighted emergence issues. The non-wetting areas can be mapped and treated by ploughing those areas paddock not the whole reducing the cost of treatment. Ground-truthing showed the 6m resolution was high enough to identify problems with the bar such as running out of fertilizer. These are management issues that can be adjusted to improve efficiency and production to improve yield.
In the case study paddock the imagery has highlighted issues that were not evident from the yield maps such as residual compaction from old corners and where the ripper and spader lifted over a water pipe (the red line in the top north east corner). This paddock has been deep ripped twice but old compaction is still visible suggesting it is beyond the current ripping depth of 400mm. The late season imagery was too late to see any big differences in biomass. An optimal time to capture imagery appears to be mid-July.
Applying low fertilizer to the low production zone is both a good economic strategy to improve profitability and prevents over fertilizing that increases the risk of nutrient leaching in these pale sands that have limited capacity to store nutrients.
|Lead research organisation||
Precision Agriculture Pty Ltd
|Host research organisation||
West Midlands Group
|Trial funding source||Australian Government|
This project “Engaging our community to improve soil health in the West Midlands” is supported by West Midlands Group, through funding from the Australian Government’s National Landcare Program.
|Other trial partners||Not specified|
|Sow rate or Target density||75kg/ha|
CaseIH Header, Ausplow DBS seeder, Ausplow multistream airseeder cart, Cat Tractor with JD guidance.
|Sow date||29 May 2015|
|Harvest date||Not specified|
|Plot size||Not specified|
|Plot replication||Not specified|
The paddock was deep ripped in March to 420mm. Seeding fertilizer KtillMOP blend (KTILL EXTRA 80%, MOP 11% and MAP 9%) with Flexi N 20L/ha Hi Load with flexi N = 150ml/ha applied as per rates in Table 1. 1st post emergent N application 80kg/ha NS 3:1 washed in on the 6/7/15. 2nd Urea application washed in 7/8/15.
glyphosate 1.5l oxyflufen 0.1l, ester 680 0.25l, Sprayseed 1l trifluralin 1.8l, metribuzin 0.08l, Paragon 0.05l, BROM MA 0.5l
Insecticides chlorpyrifos 0.3l
Fungicides Tilt 0.4 l and Prosaro 0.15l
|Rainfall trial gsr (mm)||303mm|
SILO weather estimates sourced from https://www.longpaddock.qld.gov.au/silo/
Jeffrey, S.J., Carter, J.O., Moodie, K.B. and Beswick, A.R. (2001). Using spatial interpolation to construct a comprehensive archive of Australian climate data , Environmental Modelling and Software, Vol 16/4, pp 309-330. DOI: 10.1016/S1364-8152(01)00008-1.