First of all, I would say that retaining officers is just as important as retaining the enlisted men and women in order to keep the ranks filled with quality leaders. That being the case, why don't we put more command emphasis on it?
Each battalion has a dedicated re-enlistment NCO, and re-enlistment statistics are discussed in detail generally on a monthly or quarterly basis. At meetings, a battalion commander might look at the statistics of each company's re-enlistment quotas and ask whether or not specific Soldiers might want to re-enlist. This spurs a little friendly competition between commanders because a.) well, most officers (and aviators in particular) are Type-A personalities who love to compete over maintenance stats, flying hours, physical fitness scores, etc., but more importantly b.) re-enlistment stats say a lot about a commander's effectiveness. More Soldiers will want to re-enlist if they have faith in their chain of command, simply put.
The same applies to officers, and we should apply many of the same techniques to retaining them. For those not in the military, I need to draw an important distinction between officers and enlisted personnel. While enlisted personnel sign a contract for, say, two to six years and must renew their contract if they choose to stay in the military further--a process known as "re-enlistment", officers simply remain in service--after an initial obligation of a few years--until they resign their officer's commission. As such, officers generally do not receive re-enlistment bonuses and the like.
What I am about to offer is practical advice for field-grade officers. I know that you cannot give out bonuses to your officers, but you can at least bring them in for regular career counseling--maybe once a year--just like you would with your enlisted Soldiers and their re-enlistment counseling. In other words, you need to talk to your officers, and more importantly, listen to what the have to say. It never ceases to amaze me when commanders are shocked that junior officers are leaving the military--did they ever take the time to sit down with their captains and lieutenants and ask?
During these sessions, leaders ask Soldiers and their spouses about their career and life plans, their ambitions, and how they hope to achieve them. In such a fashion, platoon leaders need to be counseled by their company commanders. Company commanders must be counseled by their battalion commanders. Most importantly, the plethora of captains and lieutenants stuck on battalion and brigade staffs must be counseled by field-grade supervisors. These are the ones that most often get lost in the shuffle, and often decide to leave based on a perception that few people care for their well-being.
A good command climate also works wonders for officer retention. It's difficult to list everything which comes into play in a good command climate, but most importantly, junior officers should see good ethical behavior, participate in a mission they find important, and feel as if all Soldiers are being treated justly. We all know that organizations should do all of these things, but I don't know that it's fully understood that organizations with horrible command climates have horrible officer retention and vice versa. In fact, some brigades (and I won't name which combat aviation brigade) have had such horrendous officer retention that they're actually used as an example of what not to do in pre-command courses.
I know that this solution is far from profound, but it's simple, it doesn't cost anything, and it's what we should be doing anyway. The hard part is finding the time to do so. However, I think we owe it to ourselves to do so--the future of our Army depends on it.