How do I set a project property through the maven command line?

I've made some progress. I've finally got the pom.xml file to pass in the parameter I wanted for the project property. I deleted the custom project property from the SoapUI and changed the xml to have this instead: 

<projectProperties>
<value>testExecution=${projectProperty}</value>
</projectProperties>

I then defined the projectProperty later in the pom right before </project> : 

<properties>
<projectProperty>Smoke_Test</projectProperty>
</properties>
</project>

Trying now to change the value of project property. I've tried -Dproperties.projectProperty=new_val but no luck. 

Alright figured it out. I changed the project property value (the one right before </project>) to $(projectProperty) and now I can use -DprojectProperty="any_val" to pass in whatever I want. Hope this helps someone later 

Edit: I should note that in order to actually use the property in the test cases, I had used a groovy script and the get data to define it in a script. However, since I deleted it after it won't show up anymore but you can still define the property like such: 

def testExecution = context.expand( '${#Project#testExecution}' )    // the property name is 'testExecution' in my case

I'm not sure whether or not it would work if I hadn't deleted the custom property. It may not have made a difference.