Powershell - Add property bag to WebApplication or Site level

# Web Application Level

$webAppUrl ="http://devvWebApp.com";

$key = "RKUTestFrmKey";

$value ="RKUTestFrmVal";

$spwebApp=Get-SPWebApplication -Identity $webAppUrl;

if($spwebApp.Properties.ContainsKey($key) -eq $False)

{

 $spwebApp.Properties.Add($key,$value);

 $spwebApp.Update();       

}

Write-Host $spwebApp.Properties[$key]

# Site Level Property Bag

$siteurl = "http://devvWebApp.com";

$site = New-Object Microsoft.SharePoint.SPSite($siteurl)

$rootWeb = $site.RootWeb

$rootWeb.Properties.Add("RKUtest", "ValueRKUTest");

$rootWeb.Properties.Update();

Write-Host $rootWeb.Properties["RKUtest"];