How to load more resources which are out of the application env?

I have a application.ini like this

[production]
phpSettings.display_startup_errors = 1
phpSettings.display_errors = 1
includePaths.library = APPLICATION_PATH "/../library"
bootstrap.path = APPLICATION_PATH "/Bootstrap.php"
bootstrap.class = "Bootstrap"
resources.frontController.moduleDirectory = APPLICATION_PATH "/modules"
resources.modules[] = ""

[staging : production]

[testing : production]
phpSettings.display_startup_errors = 1
phpSettings.display_errors = 1

[development : production]
phpSettings.display_startup_errors = 1
phpSettings.display_errors = 1

[database]
resources.db.adapter               = PDO_MYSQL
resources.db.params.dbname         = "ccgss"
resources.db.params.username       = "root"
resources.db.params.password       = ""
resources.db.params.hostname       = "localhost"
resources.db.isDefaultTableAdapter = true

[layout]
layoutPath = APPLICATION_PATH "/layouts"
layout = default
contentKey = "content"

By default, zend framework loads the [production] section. How do I load automatically the others sections?

Additionally

How do I change the environments between staging, testing, development and on?

To switch your application's environments between production, development, etc. simply set the variable to appropriate value in your .htaccess file:

SetEnv APPLICATION_ENV development

If you'd like to auto-load your own resource plugins from the bootstrap, you can do that by just tacking it onto the resources array:

resources.myplugin.param1 = "myvalue"

Don't forget to add your plugin's namespace and directory path to the pluginsPath value as well, or ZF won't know where to look:

pluginPaths.My_Resource_Namespace = "My/Namespace/Folder"

Finally, if you want to acces values in your config file without using a resources plugin, you can load the file using the Zend_Config_Ini class:

$config = new Zend_Config_Ini('/path/to/config.ini', 'staging');