The document discusses various soil and landscape mapping technologies utilized in precision agriculture to enhance yield and manage constraints. It outlines the processes for variable rate applications of lime and phosphorus, emphasizing the benefits of direct soil mapping and using EM38 sensors for soil conductivity mapping. It also highlights the importance of integrating yield data and soil analysis for effective crop management strategies.

1. Soil & Landscape
Mapping Technologies
Brendan Torpy, Precision Agriculture
@AgPrecision

2.  Actively manage PREDICTABLE and KEY YIELD CONSTRAINT issues
 Direct map soil pH, Colwell P & Colwell K variability
 Map soil/landscape variability – Texture, rooting depth, subsoil
constraints, OC
 Use NDVI and yield maps to record the success of above and help
define problem areas for targeted actions
Precision Ag Principles

3. Our PA cycle
DATA
INSIGHTACTION
Powering agriculture through the application of technology

4. Typical Precision Ag Road Map
1) Digital Farm Maps
2) Variable Rate Lime
3) Variable Rate P
4) EM38 & Topography Mapping – Gypsum, Nitrogen, Drainage
5) Satellite Imagery & Yield Data

5. Typical Precision Ag Road Map
1) Digital Farm Maps
2) Variable Rate Lime
3) Variable Rate P
4) EM38 & Topography Mapping – Gypsum, Nitrogen, Drainage
5) Satellite Imagery & Yield Data

6. Direct Soil Mapping
Rapid soil sampling and soil laboratory analysis enables grid:
 Soil pH(cacl2) VR Lime
 Phosphorus VR Phosphorus
 Potassium VR Potassium

7. Direct Soil Mapping
2ha sampling grid
8 x 0-10cm cores collected over 100m transect per 2ha
Each soil sample lab analysed at accredited lab
Strategic soil texture & PBI measurements

8. VR Lime South West VIC
 51ha paddock, Pura Pura - Target pH 5.5 (CaCl2)
 Traditional Approach (2.5t/ha lime blanket rate) = 128
tonnes
 VR Approach (average rate = 1.1t/ha) = 56 tonnes
 Lime Cost = $45/tonne (delivered & spread)
 Lime Saving = 72 tonnes or $3,240 (56%)
 Mapping Cost = $714
 Total Saving = $2,526 (3.5:1 ROI)

9. VR Phosphorus
Colwell P measurements on 2ha grid
20% savings without yield penalties
Integrate PBI, target yields into VR
decisions

10. 45ha paddock, South West Victoria
10ha (22%) below critical Colwell P level
23ha (50%) standard rate
12ha (28%) reduced rate
Opportunities for 20-30% MAP savings
VR Phosphorus

11. VR Phosphorus Seeder vs Spreader
Seeder limitations limiting VR P – not wanting to vary traces/fungicides
Seeding base rate
Pre-sowing VR P spreading
Science suggests surface spread OK if being applied for maintenance
purposes NOT for response that season

12. Typical Precision Ag Road Map
1) Digital Farm Maps
2) Variable Rate Lime
3) Variable Rate P
4) EM38 & Topography Mapping – Gypsum, Nitrogen, Drainage
5) Satellite Imagery & Yield Data

13. An EM38 sensor measures the bulk/apparent electrical
conductivity of soils.
Water
Salts
Clay
Rock
Within the soil profile
Soil Conductivity Mapping
EM38 sensors are most sensitive to soil
conductivity at depths of 0.3-0.5m and
0.75-1m.
Ideally mapped at
drained upper limit or
when profile is
completely dry

14. Why map your soils?
When it makes sense to do so!
 When there is a clear link between soil type and production,
thus potential for zonal management
 Accurately defining known soil/landscape constraints such
as salinity, sodicity, waterlogging and sand ridges
You may only need to map certain paddocks? Integrate into a
Precision Ag Implementation Plan for your farm

15. Landscape Zoning – EM38 & Elevation
EM38 & Elevation
One off investment
Delineate soil texture zones, PAWC
Ground truth to understand soil
characteristics/constraints
Assist with gypsum, drainage and nitrogen
management
Sandy Loam
Organic Carbon 1.7%
Salt below 60cm
Sandy Clay Loam
Organic Carbon 3.5%

16. 3.8t/ha
2.5t/ha
Soil Conductivity (EM38) Survey 2015 Wheat Yield

17. Soil & Plant Relationships
Avoid trying to draw conclusions from years of historical data
Focus on key years/crop types relevant to the issue being managed
First focus on yield unlock opportunities
Second focus on managing inputs to potential

18. Yield Maps and Farmer
Knowledge
Prescription map with calibration strip

19. 520ha
Crop establishment response to soil texture
Crop biomass (NDVI) tells the story

20. Potential Actions from Soil Maps
pH Mapping VR lime
Nutrient Mapping VR P & K fertiliser
Elevation Mapping Drainage
Soil EM mapping coupled with zonal soil testing
VR nitrogen *
VR gypsum and manure *
VR seeding*
Crop rotations
Strategic pest control*
* Integrate yield and/or NDVI data
to develop strategy

21. Rapid Soil Analysis on the Horizon
X-Ray and Spectrometry technology
Potential for instant results for soil
WHC, pH and numerous chemical
and physical attributes

22.  Use PA to help address key yield limiting constraints first
 Focus on the need, not the technology!
 Have a road map for implementing PA
 Direct soil mapping - VR Lime & P
 EM38 & Elevation mapping - VR Gypsum, drainage, N management
 Integrate NDVI & Yield to develop yield unlock strategies
Summary

23. 1800 PRECISION AG (1800 773 247)
INFO@PRECISIONAGRICULTURE.COM.AU
PRECISIONAGRICULTURE.COM.AU
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