This was my go to method of basing for a good number of years. I believe I found out how to do it off the website http://www.dropship.org.uk . The author (Carl Woodrow) has since migrated to a blog, although I must say I only discovered this in the last 5 minutes as I couldn't remember what the name of the original site was for years. I did remember his 'sand jackal' marines which allowed me to Google it though. Most interestingly (to myself), I think I first found dropship horizon, in the past the mecca for all matters 15mm, but hunting for Carl's site. And thus my interest in 15mm sci fi began.
Back to the point: Basing. This method is fairly slow (it takes multiple steps), but gives you a lot of control over the final colour of the ground. The layers of dry brushing give a bit more depth than the other methods I use now. One problem is that it isn't as robust, so chipping will occur over time, and the silica sand is white underneath, which makes damage quite noticeable. It is a very cheap approach.
-white (or carpenters in my case) glue
-silica sand (I procured from an aquarium shoppe)
-paint (black, yellowish, and khaki ish)
-1-2 crappy brush (1 for glue, 1 to drybrush)
The directions after the break.....
Paint watered down glue on the base. Take care as this is where the sand will stick.
It's faster to have it flow right off the brush into the sand, rather than needing to really 'paint' the sand black.
Post black painting.
Dry brush the 1st colour fairly heavily. The second (khaki ish/bone) colour gets a light dry brush.
This may be good enough for many people. At this point you can choose to add your static grass/flock. I like the effect of the ground so I err on less material being an accent to the ground.
Straight (non diluted) glue is painted on, static grass is sprinkled and/or blotted onto the glue. Flip the fig, flick/tap to remove loose stuff. Let dry. Voila.
The top picture is the result.