Though the case for maintaining the even increasing agricultural resource productivity seems quite clear, the definition of maintenance research seems to be less so. I will proceed with an examination of what maintenance research is perceived to be, and how it is to be differentiated from non-maintenance research. Some evidence on the scope and nature of maintenance research activities will then be considered. Next, I will present some results from attempts to estimate structures formulated specifically to quantify the processes involved. The paper then concludes with some observations about possibilities for future work.