Reinforcement troops Edit
In general, those supplying reinforcements are expected to feed them, by transferring an allowance of wheat. It may be better to spread the transfers, to avoid relying too much on granary capacity.
If Reinforcements are in danger of starving (and they are the first to do so), then it is better to dismiss them.
Own troops Edit
The worst case of negative wheat, is when there is not enough production to support the buildings, since this cannot be rectified by the loss of troops, This can only arise if crop fields or other crop production buildings are damaged by catapult attack, a strategy referred to as a "wheat-kill" or "croplock" OR if your +25% crop production, that has been bought with gold, has run out.
Getting out of this situation is difficult, with deleting and starting again an option to consider.
If a marketplace is still available, then trading for wheat and using it to rebuild fields is possible, though the arrival time is critical. With no marketplace, having a friend send wheat is another option.
If the main building is level 10 or better, demolishing non-essential buildings may be a way out of negative wheat.
Advanced wheat management Edit
Typically, managing World Wonder villages, artifact villages, or heavily reinforced villages is extremely difficult. The wheat consumption is huge, and even full granaries get depleted in a matter of minutes. The only solution is to keep sending merchants with wheat ahead of time. One must schedule their arrival perfectly. Send them too soon - and wheat will be wasted because your merchants will arrive when the granary is fully stocked. Send them too late - and your troops will starve because the granary will get empty.
Several wheat management tools exist, which can help alleviate the negative wheat situations. Players can copy their market page into the wheat management tool, upon which they are given a prediction of when their granary will run out of wheat. It will show when the crop is coming in from merchants, ideally, the aim is to keep the granary in your village over 25% at all times. To prevent overflow, crop is usually sent to 'feeder' villages, so that in the times when it looks like the crop will run out, the account holder ships the crop from te feeder villages so as to balance the crop.
Without crop management tools, it would be impossible to see when crop would run out, additionally it would be impossible to see when there will be crop overflow.
Generally, these tools are hosted web services. The best that are up to date for the current version of T4 is: