Nev Boland was sick and tired of farming through 'Melonholes' or 'Gilgais' on the family farm at Moonie Queensland, Australia.

“Melonholes are irregular depressions ranging in depth from 30cm to 150 cm deep and 1 to 15m across , which can really spoil your day if you are farming them in rainy seasons.” said Nev.

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.

Also the steeper edges of the gilgais approached 5% slope. This increases runoff into the bottom of the gilgais and reduces infiltration other areas of the field, therefore reducing the crop yield of the field even further.

This video shows how a tracked harvester was required before OptiSurface Landforming:

Below are some maps of the existing field before OptiSurface.

Drainage Analysis based on surveyed topography shows 17% of the field or (37.8 hectares or 93.4 acres) experiences standing water.

Yield Loss From Water Logged Areas
Say an average yield reduction of 25% over 17% (37.8ha) of the field with a gross income of $2000/ha from cotton and wheat rotation  = $18,900/yr

Yield Loss From Less Timeliness of Planting and Harvest
Say an average yield reduction of 5% over 222ha of the field with a gross income of $2000/ha from cotton and wheat rotation = $22,200/yr

Yield Loss From Reduced Infiltration Uniformity
Say an average yield reduction of 5% over 222a of the field with a gross income of $2000/ha from cotton and wheat rotation = $22,200/yr

Estimated Total Cost Of Surface Drainage Problems = $63,300 per yr

An OptiSurface 4Way design was generated for the field with a minimum grade of 0.05% to promote drainage. A smoothing of 100 m/% was also applied to promote more uniform infiltration of rainfall.

Earthworks
Volume of Cut: 80,540 m³ or 105,342 yd³
Volume Of Fill:  66,600 m³ or 87,110 yd³
Average Cut per Area: 363m³/ha  or 192 yd³/acre
Cost: $55,500 based on a coverage rate of 3 ha/hr @ $250/hr = $83/ha per pass ($33/acre per pass). With three passes over the field to do earthworks total cost is (3 x $83) $250/ha or $100/acre.

Survey and Design
222ha at $25/ha = $5550

Total Cost Of Surface Drainage Solution: $61,000

A shallow waterway or drain was also integrated into the design.  This waterway was designed with a slope along it's length of 0.04% resulting in a 0.234m cut at the exit.  The waterway was designed using breaklines with a 5m wide flat base battering up to the surface at 1:10.

See images below for the waterway.

We spoke to Nev during the earthworks operations. He said “The levelling is going well. We have the northern part of the paddock nearly finished which is 175ha. I will have to use the carry all bucket to carry a small amount of dirt to fill around the drain and do a final trim over the paddock, but otherwise all is good.”

“We did two passes overall , then concentrated on bad areas with a lot of circle work etc . Hopefully today or tonight the 175ha will be done with the pulldozer . It has 166 hours on the clock now. It will still need a touch up with the carry all bucket to carry a bit of dirt to a few isolated holes, probably take a day or two of this then its all done . A lot quicker then the 1 acre per hour (0.4ha/hr) with the laser bucket and multiplane we used to average.”

He is using a 7.2m (24ft) wide pulldozer imported from Canada along with one of the world’s most powerful production (585hp) tractors, the Cat MT875C. It is taking about 3 passes to get to the finished design surface. Due to the extensive melonhole topography, a significant amount of soil was require to fill the depressions and the design came at an average of 380 m3/ha (200yd3/acre).

A major advantage of the OptiSurface design is that almost all of the field was continuous cut-fill-cut-fill with no large areas of continuous cut or fill. This suits the pulldozer and makes it very efficient earthmoving and limits any remediation required in deep cut areas.

He is averaging about 3 ha per hour with three passes resulting in a finished rate of 1ha/hr (2.5 acre/hr). That also equates to an earth-moving productivity of about 380m3/hr (500yd3/hr) which is very good going but he doesn’t have to shift the earth too far as he is typically cutting for 15m then filling for 15m as shown in the video below. Assuming a total cost rate of $250/hr for the machine and operator, 380m3/hr (500yd3/hr) equates to around $0.66/m3 ($0.50/yd3) which is a very low cost per cubic meter.

A coverage rate of 3 ha/hr @ $250/hr = $83/ha per pass ($33/acre per pass).
With three passes over the field to do earthworks total cost is (3 x $83) $250/ha or $100/acre.

Watch the machine in action on the video below (Thanks to Nev Boland for the great video).

Based on a total cost $61,000 and a benefit of $63,300 per year, the payback period is only 0.9 years!

Now that's an annual return of  over 100% for an operation that lasts many years if not forever. That's why we believe OptiSurface is likely the highest Return On Investment (ROI) farm improvement you can do.