Remote sensing in irrigated

onion production: Challenges

& opportunities

Hort Connections 2017

Adelaide Convention Centre

Michael Cutting, Natural Resources SA MDB Region

Project Background:

• In 2004/05 an extensive automatic weather station network was established across the SA Murray-Darling Basin region

• Primary objective was to provide land managers with real time and location specific weather data to assist with on-farm decision making

• High density of stations in key irrigation areas across the region – River Murray, Mallee

• Daily evapotranspiration data to assist with optimising irrigation scheduling

Project Background:

• Given the significant investment keen to promote the on-farm adoption of network data

• Looked into different decision support systems and tools that integrated on-ground weather data

• Collaborated on small scale trials of different remote sensing based systems including IrriEYE

IrriEYE:• IrriEYE is an irrigation advisory

service based on high resolution satellite monitoring of canopy satellite monitoring of canopy development

• IrriEYE provides farmers and water managers with real-time irrigation water needs from field and irrigation unit to district and river basin scale

• Generates crop co-efficient values that are then applied to local ETodata sourced from AWS

• Citrus, wine-grapes, almonds, stonefruit (2011 - 2013)

Remote sensing: A tool to monitor & evaluate?

• Since 2010 the SA MDB NRM Board has been involved as a Delivery Partner in the Australian Government funded On-Farm Irrigation Efficiency Program (OFIEP)

• OFIEP is a key water recovery initiative linked to the Murray-Darling Basin Plan

• Share of water savings generated through on-farm irrigation efficiency improvements returned to the environment

• What innovative ways could we evaluate on-farm improvements? before vs. after assessments

Remote sensing: A tool to monitor & evaluate?

• High resolution imagery (fixed wing aircraft)• Water stress mapping (ambient vs. in canopy air temp)• Note: Not deriving an irrigation volume

The IrriSAT system:

• With continuing drivers to extend weather based irrigation scheduling approaches along with monitoring and evaluation activities we started to utilise the IrriSAT system

• We were already familiar with the IrriSAT system from when it was developed through CRC for Irrigation Futures

• The IrriSAT methodology uses satellite images to determine the Normalized Difference Vegetation Index (NDVI) for each field

• https://irrisat-cloud.appspot.com/#

Benefits of the IrriSAT system:

• It is free! Just need a Gmail account

• Able to easily map specific patches/plots of interest

• IrriSAT system delivers regular satellite imagery – Sentinel 2 & Landsat 7/8

• Can generate a crop water balance and soil water deficit – based on inputs (irrigation + rainfall)

• Also produces a forecast of crop water use based on crop coefficients derived from the satellite imagery

Monitoring sites in 2016/17 season:

• Crop Types: Lucerne, perennial pasture, wine grapes, onions• Irrigation Systems: Centre Pivot, Fixed Sprinklers, Border Check

• Sites were largely project based• Not a formal trial of IrriSAT• Value add to existing work programs

Onion monitoring sites in 2016/17 season:

• Sites were largely project based• Not a formal trial• Value add to existing work

Plant: 17/06/16Harvest: 28/12/16

Plant: 18/09/16Harvest: 24/02/17

Plant: 01/06/16Harvest: 04/12/16

• Onion site was chosen as farmer was using weather based approach to irrigation scheduling

• Collaborated with previous work (plant based)• Good with feedback

Onion monitoring sites in 2016/17 season:

Plant: 17/06/16Harvest: 28/12/16

Plant: 18/09/16Harvest: 24/02/17

Plant: 01/06/16Harvest: 04/12/16

• 9 June 2016• Sentinel 2 satellite image (10m pixel)

Onion monitoring sites in 2016/17 season:

• Sites were largely project based• Not a formal trial• Value add to existing work

Plant: 17/06/16Harvest: 28/12/16

Plant: 18/09/16Harvest: 24/02/17

Plant: 01/06/16Harvest: 04/12/16

• 11 July 2016• Note bottom (orange) patch not yet planted

4 weeks

6 weeks

Onion monitoring sites in 2016/17 season:

• Sites were largely project based• Not a formal trial• Value add to existing work

Plant: 17/06/16Harvest: 28/12/16

Plant: 18/09/16Harvest: 24/02/17

Plant: 01/06/16Harvest: 04/12/16

• 29 September 2016• Influence of composite images – Landsat 8 (30m)

& Sentinel 2 (10m) - different resolutions

Cloud cover – Sentinel 2 excludes areas influenced

Onion monitoring sites in 2016/17 season:

• Sites were largely project based• Not a formal trial• Value add to existing work

Plant: 17/06/16Harvest: 28/12/16

Plant: 18/09/16Harvest: 24/02/17

Plant: 01/06/16Harvest: 04/12/16

• 7 October 2016• Landsat 8 image only – more uniformity

Cloud cover – Sentinel 2 excludes areas influenced

Onion monitoring sites in 2016/17 season:

• Sites were largely project based• Not a formal trial• Value add to existing work

Plant: 17/06/16Harvest: 28/12/16

Plant: 18/09/16Harvest: 24/02/17

Plant: 01/06/16Harvest: 04/12/16

• 31 October 2016• Crops continuing to develop > Kc value

Cloud cover – Sentinel 2 excludes areas influenced

Onion monitoring sites in 2016/17 season:

• Sites were largely project based• Not a formal trial• Value add to existing work

Plant: 17/06/16Harvest: 28/12/16

Plant: 18/09/16Harvest: 24/02/17

Plant: 01/06/16Harvest: 04/12/16

• 18 December 2016• Several beds not yet harvested• Not a strong signature on late planting

Cloud cover – Sentinel 2 excludes areas influenced

Onion monitoring sites in 2016/17 season:

• Sites were largely project based• Not a formal trial• Value add to existing work

Plant: 17/06/16Harvest: 28/12/16

Plant: 18/09/16Harvest: 24/02/17

Plant: 01/06/16Harvest: 04/12/16

• 26 December 2016• NE plot harvested 04/12/16• Within crop variation visible in S plot

Cloud cover – Sentinel 2 excludes areas influenced

Onion monitoring sites in 2016/17 season:

• Sites were largely project based• Not a formal trial• Value add to existing work

Plant: 17/06/16Harvest: 28/12/16

Plant: 18/09/16Harvest: 24/02/17

Plant: 01/06/16Harvest: 04/12/16

• 17 January 2017• Persistence of low vigour - circle

Cloud cover – Sentinel 2 excludes areas influenced

Onion monitoring sites in 2016/17 season:

• Sites were largely project based• Not a formal trial• Value add to existing work

Plant: 17/06/16Harvest: 28/12/16

Plant: 18/09/16Harvest: 24/02/17

Plant: 01/06/16Harvest: 04/12/16

• Whole of season statistics• Field Visibility (%)• Comparison to actual

Cloud cover – Sentinel 2 excludes areas influenced

Key observations and lessons:

• Sites were largely project based• Not a formal trial• Value add to existing work

Plant: 17/06/16Harvest: 28/12/16

Plant: 18/09/16Harvest: 24/02/17

Plant: 01/06/16Harvest: 04/12/16

Cloud cover – Sentinel 2 excludes areas influenced

• Can be challenges with the IrriSATapproach to onion irrigation management:

- establishment with cover crop - not a bulky crop (biomass)

• Despite this the system provides a very visual assessment of crop uniformity –assists with troubleshooting

• We did not incorporate local AWS data but SILO evapotranspiration was very similar: 924mm (SILO) vs. 981mm (local)

• Published crop co-efficient data for onions suggest 1:1 with ETo ~ 9ML/ha

• Accurate ETo forecast = valued by farmer

thankyou