PICTURE a group of generals around a large scale simulated battlefield, complete with appropriate plastic figures, tanks and canons, all strategically positioned at the "enemy". It will give you some idea of what Digital Elevation Modelling (DEM) is all about. To carry the analogy a little further, replace the generals with members of the Upper Coblinine Catchment Group (south-east Katanning), use DEM to mark out the "battlefield" of 16 farms covering 42,000 hectares and replace the plastic figurines with trees, contour banks and crops < all strategically positioned at the "enemy", which in this case is salt encroachment. Now comes the interesting part. What to deploy against the "enemy" and in what order? For Mindarabin farmer and catchment group member Simon Hill, answers to those questions will come from DEM, which basically uses digital photogrammetric technology to convert aerial photography into a virtual three dimensional model accurate to within 75cm. "There is potential with such a 3D view of the topography to identify hidden creek lines and general water flow patterns and other geological data such as dikes and soil types," Simon said. "It's early days yet and, even with this technology, there's a lot of what ifs that come into the equation. "We're concentrating on testing all current remediation theories to see what is economically feasible. "The underlying problem to a solution, however, is the limited number of options in the catchment, which comprises mostly duplex soils 30cm deep. "We don't know how many years out of 10 we will have to grow lucerne or what successes we might have with summer cropping. "But it's something we have to address because salt is becoming a problem and we feel the only sensible way to attack it is with a catchment scale plan to identify recharge areas and do modelling to alleviate flooding. "With this new hill and valley-type technology, we can easily determine where the water will flow, so it then becomes a matter of determining which strategies to employ. "Everybody is open minded, we're just after cost effective solutions. "The best fit in one area maybe trees, in another area crop and in another a contour bank or a combination of things." With a 5000ha arable farm, Simon maintains an 80-20 mix of cropping with sheep and pastures. While the past few years have been "bloody hard", with increasing cost inputs and declining commodity prices, Simon still retains a positive attitude and is confident he can achieve a profitable and sustainable farming system. He has been a 100 per cent so-called no-till farmer since 1993, when he imported the first Canadian-built ConservaPak seeding and tillage system into Australia. After two seasons of trialling the machine, Simon's father Ian and neighbor Chris Perry took on the Australian franchise through their Katanning-based company, Burando Hill. "If I hadn't moved to no-till then I know I wouldn't be farming on this scale today," Simon said. "No-till has enabled me to increase my cropping economy of scale and I have been able to maintain some profitability. "There's no doubt I would be far worse off with the gross margins had I maintained a conventional farming approach." As far as Simon is concerned, the concept of almost nil soil disturbance with an agronomic package came "just in time". "The ConservaPak system has improved timing of seeding, with the bonus of proper placement of seed and fertiliser while improving soil structure. "You know you're on to something when you see soil structure improving all the time and you can feel the soil becoming better structured," Simon said. "And there's the improved grain quality with lower screenings. "I'm also seeing returns from quicker stubble breakdown in continuous cropping in the form of building up organic nitrogen levels."