The animals gather together on the farm and sing of the farmer's sos being in the army -- there are five stars on the banner at the house, which means there are five men in the armed forces. There's no one to farm, so they proceed to farm the land, singing about their contribution to the war effort in this wartime Terrytoon.
All of the cartoon studios did war work, and they all produced cartoons that celebrated the war effort -- some of them are banned today because of their contemporary views of Japanese and Germans, now considered racist, although you can find them on Youtube easily enough. Paul Terry's studio produced a goodly number of them, but this one has a bit of a bizarre subtext as food animals cheerfully grow and harvest crops. The usual Terry gags are scattered throughout, including one very good one about caterpillars, but this cartoon looks a bit too rote and standard to be very interesting.