The Penetrometer – A handy tool to test compaction

Grasser: All right. Well, we know what the penetrometer does, don’t we? We poke it in the ground, and if you don’t have the penetrometer, you can get a bit of fencing wire and do the same thing. We know that there’s a magical number on here, which is not marked, between 200 and 400, the centre point between those two, which is 300 on the red scale, 300 psi. Basically, that pressure starts to be indicated when you put some pressure down onto it, and we’re about reaching 300 psi now.

Grasser: That’s a point. So at that depth, we should find when we dig our hole that at about that depth there will be probably limited or restricted root activity at the moment. There might be residual roots there from previous season, but at this point in time, now we’re re-saturating the soil, the roots are probably getting down, the fresh ones, are probably getting down that far and then stopping.

Grasser: Well, so what we do is we go around and do that in a number of places. I’m going to turn around so I can see the dial indicator on there. I encourage you all to have a go with this and walk around. Now, this is actually a lot softer and we’re getting to 300 psi about now.

Woman: Yeah, we put a bale on it.

Grasser: So the point is that you don’t just take one spot in a paddock and say, that’s it, and that’s what the rest of the paddock is like. You actually go around the paddock. If I was trying to get a handle on how this paddock was laying, I’d probably put at least ten or a dozen probes in there with the penetrometer. It’s not hard work, normally. In the middle of summer –

Woman: Just set up a grid or something, so [INAUDIBLE] replicable [INAUDIBLE].

Grasser: Yep.

Man: Fluoro paint.


This is a clip from “Walk the Talk” with Gerhard Grasser: Healthy Soils, Healthy People filming available for Farming Secrets Members.

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