Optisurface Earthworks Solutions

Keytah Dryland Drainage Application (Part 2)

The following example has been added to the OptiSurface Website at http://optisurface.com/~davcofar/optisurface/index.php?/keytahexample. It is repeated below.

Keytah Success Story –  Dryland Cotton And Wheat


Keytah is a 53,000 acre dryland and irrigated cropping and cattle operation owned by Sundown Pastoral Co and situated west of Moree, NSW, Australia. Manager Andrew Parkes is recognised as an industry leader when it comes to apply innovations on-farm and he saw the large potential for OptiSurface in improving Keytahs dryland framing operaton. He selected a problematic field for the first application.

Location: “Keytah”, Moree, NSW, Australia

Field Area: 297 ha or  743 acres

Irrigation Method: No Irrigation. Dryland/Rainfed

Crops: Wheat, Cotton

This field experiences water ponding a number of times per year after significant rainfall events. Ponding Analysis (see image below) based on surveyed topography shows over 25% of the field or (74 hectares or 185 acres) experiences standing water. This creates water logging problems for crops in these areas but also delays timely machine operations for the rest of the field waiting for the ponded areas to dry out.

Yield Loss From Water Logged Areas
Say an average yield reduction of 25% over 25% (74ha) of the field with a gross income of US$2000/ha from cotton and wheat rotation  = US$37,000/yr

Yield Loss From Less Timeliness of Planting and Harvest
Say an average yield reduction of 5% over 223ha of the field with a gross income of US$2000/ha from cotton and wheat rotation = US$22,300/yr

Estimated Total Cost Of Surface Drainage Problems: US$59,300/yr

Existing Ponding Map




An Optimum Surface Landform design was generated for the field based on a desired minimum grade of 0.02%. This was lower than the 0.05% grade typically adopted as the minimum grade for drainage on other fields however the low average grade across this field meant 0.02% was adopted. See the Existing Topography, Prosposed Topography and Proposed Cut Fill Maps below.

Volume of Cut: 13,500 m3 or 17,610 yd3
Volume Of Fill:  11,600 m3 or 15,200 yd3
Average Cut per Area: 46m3/ha  or 24 yd3/acre!!
Cost: US$40,500 assuming an earthmoving rate of US$3/m3


Survey and Design
297ha at $20/ha = US$5940

Total Cost Of Surface Drainage Solution: US$46,500 

Payback Period: $46,500/$59,300 = 0.8 year. Less than one year!

Existing Topography Map



Proposed Topography



Cut Fill Map



Below is this field being landformed. Note the drainage paths that the machine is crossing is barely visible with very flat batters which is a feature of the OptiSurface design to allow easy trafficabilty with all field machinery. See more images from this field here: http://optisurface.ning.com/photo/albums/keytah-dryland-optisurface

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