Salinity control and drip irrigation for silt soils

This trial tests how different levels of drip irrigation with brackish water affect potato yields, quality and soil health

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Field Lab Timeline

    4/9/2020 11:00:00 PM
  • Install drip irrigation, initial soil assessments

    Install drip irrigation, initial soil assessments
  • 6/22/2020 11:00:00 PM
  • Weekly ground cover measurements Apr - Sept

    Weekly ground cover measurements Apr - Sept
  • 9/20/2020 11:00:00 PM
  • Field visit - visual assessment of canopy and sampling digs for tuber quality

    Field visit - visual assessment of canopy and sampling digs for tuber quality
  • 11/15/2020 12:00:00 AM
  • Yield & quality assessments, post-trial soil assessments

    Yield & quality assessments, post-trial soil assessments
  • 1/15/2021 12:00:00 AM
  • Meeting to share initial trial findings

    Meeting to share initial trial findings
  • 3/15/2021 12:00:00 AM
  • Soil quality assessments

    Soil quality assessments
  • 3/30/2021 11:00:00 PM
  • Submission of final report

    Submission of final report
For further information hover over the above milestone marks
  • Discussion

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  • Achievements

    May 2021

    Field lab results

    Key Findings:

    CROP IMPACTS:
    • Salinity treatments (fed through drip/overhead irrigation) had no impact on potato grade and yield
    • Salinity treatments did not impact levels of common scab and black dot
    • Salinity treatments did not impact skin brightness
    • Non-irrigated plots had slightly lower yields, higher levels of scab and lower skin brightness

    SOIL DAMAGE:
    • Sodium levels in the topsoil and subsoil spiked in July with brackish irrigation but this dropped by August and reverted to pre-irrigation levels by March the next year. This shows that the salts were flushed out at those soil depths.
    • There was slightly higher soil compaction in the plot with highest salinity levels (4000ppm). However, it is not possible to say whether this was due to the sodium, as this was flushed out at the depths sampled. It may be due to the location of the plot in the field
    • Visual assessments of soil structure showed marginally better soil structure form the lower salinity plots - this may be to do with the location of the plot within the field
    • There were no significant differences in CO2 respiration (an indicator of soil life) between the plots

    WATCH THE FULL VIDEO AT https://www.youtube.com/watch?v=pR4pAluJ5PU

    Final report coming soon...

    Milestone: Submission of final report

    May 2021

    System economics

    In the Holbeach Marsh area (silt soils in south Lincolnshire):

    • Drip irrigation and waster infrastructure (reservoir etc) might cost around £600/acre
    • Overhead equipment = £160/acre for 20mm application. This trial applied 80mm i.e. £640/acre
    • So drip vs overhead costs roughly the same
    • In a drier year, drip irrigation may have been more cost effective. We know from this trial that there were no yield reductions at up to 4000ppm with drip (levels above 4000ppm were not trialed).

    Milestone: Submission of final report

    May 2020

    Trial set up

    The full trial set up, including pictures, can be found in the documents section of this page.

    The five plots have been installed in a subsection of a field of Maris Piper and irrigated on the 14th May by linking the plots to IBCs diluted to their corresponding salinity levels. Soil moisture probes were installed to monitor moisture dynamics and assist irrigation scheduling, and baseline soil samples were taken by the researcher.

    Milestone: Install drip irrigation, initial soil assessments

    April 2020

    Trial confirmed and irrigation installed

    Through discussions, it was agreed that it would be most practical and cost-efficient for farm to host the trial, with knowledge disseminated to the rest of the Nene Potatoes members and non-members through knowledge exchange events facilitated by AHDB.

    The drip irrigation was installed mid April. Four sample plots have been marked out for sampling throughout the course of the trial.

    The trial design is as follows:

    TREATMENTS

    • Drip with low NaCl water ~300us/cm
    • Drip with medium NaCl water ~700us/cm
    • Drip with high NaCl water ~1900us/cm
    • Control, not irrigated

    MEASUREMENTS

    Crop:
    • Canopy across the season
    • Total yield
    • Graded yield with assessments of common scab and other tuber defects, 4 sample digs in each plot

    Ground cover and harvest assessments will be done by the potato agronomist for the farm, who regularly visits the farm.

    Soil quality:
    • Aggregate stability
    • Infiltration
    • Soil respiration

    Scheduling will be performed by Soil Moisture Sense using probes and the experience of the company to advise when and how much to irrigate. Sensors are being installed at the start of the season and can be monitored at a distance.

    The researcher will take soil measurements or if necessary, create an instructional video for the farm staff on collecting and freezing soil samples.

    Milestone: Install drip irrigation, initial soil assessments

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