We will start off with a blank canvas, and making sure our colors are default (black and white), we will goto Filter > Render > Clouds.
Next, we will add Filter > Noise > Add Noise at around 30%, but this depends upon your image size and clouds - experiment:
Goto Filter > Blur > Gaussian Blur and set it to around 1px. And then finally, Filter > Brush Strokes > Spatter. Use between 20 and 25 for the Spray Radius, and 1-3 for the Smoothness.
Now to color the dirt, we goto Image > Adjustments > Hue/Saturation. Make sure the colorize option is checked, and choose a brown color.
Create a new layer and fill it with a green color for the grass. Then goto Filter > Noise > Add Noise. Use a relatively low value - 15-30.
Now we do the same as the dirt layer - add a Gaussian Blur (Filter > Blur > Gaussian Blur) of 1px.
Next, goto Filter > Stylize > Wind, and choose the Stagger option, and From the Left.
Then goto Image > Rotate Canvas 90° CCW, and apply the Wind Filter again, but this time from the Right. Then rotate the canvas back to normal. We are left with something like this:
Your grass may need the contrast altering a little, or the color changing. To do this, goto Image > Adjustments > Brightness/Contrast and Image > Adjustments > Hue/Saturation.
Now to show some of dirt through the grass, to give it a worn look, we will add a Layer Mask to our grass layer. Click the Mask icon (
) at the bottom of the Layer panel. When in the mask, choose a sft brush and change it's opacity to 30% or so in the Brush options in the top toolbar. Use the brush to paint onto the mask where you want worn areas to show. The resulting image should look something like this:
As with everything in PhotoShop, experimentation is definitely the key. Try changing values around to see what outcomes you get.
