overseer nutrient budgets and irrigation
Download
Skip this Video
Download Presentation
OVERSEER® Nutrient budgets and Irrigation

Loading in 2 Seconds...

play fullscreen
1 / 14

OVERSEER® Nutrient budgets and Irrigation - PowerPoint PPT Presentation


  • 79 Views
  • Uploaded on

OVERSEER® Nutrient budgets and Irrigation. David Wheeler 1 , John Bright 2 1 AgResearch, Hamilton 2 Aqualinc, Christchurch. Background. Overseer is a nutrient management tool Drainage is an important driver of leaching Irrigation inputs accounted for in the drainage calculation

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' OVERSEER® Nutrient budgets and Irrigation' - ghalib


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
overseer nutrient budgets and irrigation
OVERSEER® Nutrient budgets and Irrigation

David Wheeler1, John Bright2

1AgResearch, Hamilton

2Aqualinc, Christchurch

background
Background
  • Overseer is a nutrient management tool
  • Drainage is an important driver of leaching
    • Irrigation inputs accounted for in the drainage calculation
  • Concerns about use of irrigation in Overseer
    • Aligning irrigation inputs to climate data inputs
    • Type of management options within Overseer
drainage model
Drainage model
  • Each day:
  • SMt = SMt-1 + rainfall + irrigation
  • – AET – drainage – runoff
  • Drainage occurs when soils exceed field capacity
  • The amount and timing of irrigation can affect drainage
  • Climate data determines rainfall pattern, potential evapotranspiration
inputting irrigation data into ovs
INPUTTING irrigation data into OVS

‘Method only’

‘Method plus rate’

using method only
USING ‘Method only’
  • Overseer automatically calculates the irrigation amount required to maintain high soil moisture content while minimising drainage

Saturation

Irrigation

Field capacity

0.95

Target

0.70

Trigger

AWC

Wilting point

using method only1
USING ‘Method only’
  • Includes an estimate of ‘system losses’
      • Losses due to leaks, overlaps, inefficiencies, etc
      • Added to drainage
      • Border dyke also includes outwash loss

Active management check box

      • Calculation then based on:
        • No system losses assumed
        • No irrigation applied within 5 days of rainfall

Requires nutrient concentrations in water

      • Border dyke outwash can be recycled
using method plus rate
USING ‘Method plus rate’
  • A three step process:
  • Irrigation amount estimated as per ‘method only’
  • Applied rate estimated from user-entered rate data
  • If estimated applied rate > method only rate
    • Difference added to drainage

ESSENTIAL that entered rate and climate data align

climate data
Climate data
  • User inputs to describe climate are:
    • Annual rainfall
    • Annual PET
    • Annual average temperature
  • Default PET and temperature based on long-term climate data set
  • User can define period annual data is average of, but
    • Data must be commensurate with the objectives of setting up the Overseer file, and with management input data
climate patterns
Climate patterns
  • Overseer climate database uses a ‘typical’ distribution of rainfall, PET and temperature:
    • Currently typical long-term patterns
    • Moving to site-specific long-term patterns
  • Important to align climate and irrigation rates

Illustration of long-term average rainfall patterns and variation with a single year

new work underway
New work underway
  • The following projects will add robustness to the use of irrigation in Overseer:
  • Comparison of drainage estimates under irrigation between Overseer and IrriCalc
    • Also looking into additional management options to describe irrigation use
  • Improving supporting databases:
    • Soil data
    • Default climate data
effect of management rules on calculated drainage
EFFECT of Management rules on calculated drainage

800 mm rainfall, irrigated October to February central pivot

Tentative

* Estimated irrigation rate (mm/yr)

** Estimated drainage (mm/yr)

conclusions
Conclusions
  • Recommend use ‘method only’ for now
    • This leaves Overseer to estimate the irrigation rate
    • Minimises the risk of not aligning irrigation rate and rainfall
  • If using ‘method plus rate’, then align climate and irrigation rate
    • Not recommended
    • Using this option may lead to an overestimation of drainage
  • Irrigation management rules are important
    • Investigating how to increase range of rules in Overseer
  • Look out for further updates
    • As we work through the results of the Irricalc comparison project
acknowledgments
Acknowledgments
  • OVERSEER® owners are Ministry for Primary Industries, Fertiliser Association of New Zealand and AgResearch
ad