Add the groundTypeMapping Line into the groundTypeMappings section in your map.xml Adjust the layer to the entry you made in map.i3d, also adjust the paintableFoliageId
Add the paintableFoliage Line to your paintableFoliages section in your map.xml Adjust the paintableFoliageId to the first free ID

Füge die groundTypeMapping Zeile in den groundTypeMappings Bereich hinzu. Passe den layer and den in der map.i3d verwendeten an, sowie die paintableFoliageId
Füge die paintableFoliage Zeile in den paintableFoliages Bereich hinzu. Passe die paintableFoliageId an, verwende dazu die erste freie ID

	<groundTypeMappings>
		<groundTypeMapping type="dirt2"          layer="ROUGHDIRT2" paintableFoliageId="6" />

    </groundTypeMappings>
    
    <paintableFoliages>
		<paintableFoliage id="6" layerName="dirty" firstDensityMapChannel="0" numDensityMapChannels="1" value="1"  />
    </paintableFoliages>