Choosing test category on command line

I am using JUnit's categories to split my tests into different categories and using maven to compile and run my test (surefire and failsafe).

Question is, how to I choose which category of tests are executed from command line?

something like: mvn clean install -DloadTests.

my failsafe plugin:

                 <plugin>
               <groupId>org.apache.maven.plugins</groupId>
               <artifactId>maven-failsafe-plugin</artifactId>
               <version>${failsafe.plugin.version}</version>
               <configuration>
                <!--Exclude load tests by default-->
                 <excludedGroups>com.test.lib.categories.LoadTestCategory</excludedGroups>
               </configuration>
             </plugin>