Negative Resource Output

What does it mean to have negative resource output/h?

You have too much troops. Occupy an oasis or upgrade your buildings to lessen the negative

[support1]

Because your troop（Infantry 1 per hour, Cavalry 4 per hour, Archer2 per hour, and Siege Engine 10 per hour) is consuming your crops.
As a result, the crop output sometimes maybe negative, what you can do now is to upgrade the cropland, upgrade planting skill in the tech, enchance crop output,occupy oasis crop or buy crops directly.

negetive output means that you are losing that much of the resource per hour

Mind you negative output should only occur in regards to crop though I heard something strange said that players have experienced negative other resource output though I'm hard pressed to believe it.

I had 1 time a negative output in iron ??
But lasted only a few sec.. I had just trsnsfered in 200000 into city, and was spam pressing update button on my turrets beacuse i had to rush to command
After i presses ugrade on turrets i swiped wrong and ended up in "city oversight" there i noticed - red on iron.. But rushed on to command screen.. When i came back it was gone
Always thought i just overloaded the mathcalc for a few sec..