VRT – my experiences as a grower WMG Updates 2015 Erin Cahill

“Insanity is doing the same thing over and over again and expecting a different result” Albert Einstein

Overview Background Steps to adoption Tools used Examples Summary

Our Operation Own, Lease and Sharefarm 1450ha Full cropping – Wheat,Barley,Canola,Lupins Two locations 53 km apart – Highly variable soils “Dalkey” (Walebing) - High production (High inputs) York gum loams, White gum gravelly loams Mallee gravels and cap-rock “Elsewhere” (Rowes Rd) – Medium production Casuarina gravelly duplex Pear tree yellow sand Blackbutt sands

VR – the journey so far Yield mapping since 2007 (Case AFS) Auto steer 2007 ( JD Greenstar) Mapped all paddock boundaries 2007 Prior to 2009 varying rates paddock to paddock but not within (except K) > map based variable rate post-em nitrogen only 2008 and 2009 collected PCD data for whole farm

VR – the journey so far 2009 – New Morris airseeder tank (Topcon controller) 2010 began map based VR at seeding -Issues with different systems talking to each other -map prep clunky and time consuming Beginning 2012 converted airseeder to Greenstar 2012 EM 38/ radiometric survey part of farm 2014 completed EM 38/ radiometric survey rest of farm

Tools I use for VR Soil testing – all paddocks 0-30cm, some 0-50cm & 0-1m Plant test – every year High Res aerial photography or google -cheap Yield maps – Minimum 3 years Guidance shapefiles- collect ASAP Biomass imagery (20m x 20 m) DMS imagery (Plant cell density 1m x 1m)) EM 38/ Radiometrics

Tools I use for VR JD Apex SMS advanced (yield maps) VA Gateway Google Earth I Pad – ground truthing Penetrometer Shovel !

Building Layers to manage Risk

VR processes Target soil sampling sites Identify and isolate main production limitations Ground truth to understand drivers of variability – shallow soils, non wetting, weeds, root disease, vermin Quantify production potential (go to yield maps) Identify potential management zones Keep application strategy simple Use loss of GPS/out of field rate as my rate for main zone

VR Nitrogen

Yield Maps Are a tool in the kit bag – nothing more Easy and cheap to collect- start now 1 year of yield mapping is inadequate for VR 3 years of good quality yield maps as a minimum is required to get a good picture of “true” spatial variability are useless unless they are used to identify, understand and then manage the drivers of variability.

VR Process Keep simple- 3-4 zones per paddock Keep Zone boundaries practical for machinery Make rate changes worthwhile - Min kg/ha Compound (3-4 kg/ha P) - Min l/h a Flexi N (10-13 kg/ha N) Better matching of inputs to yield potential We are not using less fertiliser (just using it better)

VR Nitogen – Manually Done

VR simple example

Weed mapping Wild oats Spray all (80 ha & $2000) Or patch spray (28 ha & $700)

Results 2010 Average N saving $7-8/ha 2012 Average N saving $15-16/ha Significant grain quality improvements (malt barley) Yields achieved in the most productive parts of paddocks have increased Not wasting $ on poor/constrained areas Compound fert better allocation of $ (no real saving) Identifing more areas to “fix”

Summary Pick your GPS/VR system and fit machinery around it (one system throughout is best) Try not to be the guinea pig  Collect good data even if you aren’t using it now Use documentation systems Limit guess work Be clear about what you are varying and why Ground truth Don’t over commit in the early stages- time hungry

Summary VR applications need constant re-evaluation – what was once a poor area may become a productive one if limitations are rectified Use Check strips and analyse outcomes Don’t vary rates just for the sake of it Remember the goals are improved productivity and profitability

Thankyou & Questions

Nutrient Budget approach to VRT Works on the basis of replacing what is removed Only works when we are in a situation where we can maintenance fertilise! Makes no effort to understand drivers of spatial variability Makes no allowance for losses due to soil reactions Makes no allowance for the fact that it takes more nutrients to grow a crop than are removed eg to grow 1 t/ha wheat takes 50 kg N ha 1 t/ha wheat removes 20 kg N ha

Paddock variations drive savings

Paddock 1 71 ha Outside lap 3.38 km 14% of paddock area (10.14 ha) with a 30m swath 11% of paddock area (8.11 ha) with a 24m swath Paddock 2 69 ha Outside lap 8.69 km 37 %of paddock area (26 ha) with a 30m swath 30% of paddock area (20.85 ha) with a 24m swath Paddock variations drive savings

Understand biggest limiting factor