This study measures the amount of agricultural research engaged in maintenance research for commodities and non-commodities. The percentage of commodity based maintenance research has risen from roughly 35% in 1986 to 41% in 2008. The percentage of non-commodity based agricultural research is roughly 29%. Additionally, an empirical model is developed to explain maintenance research expenditures. The influences of agricultural research funding, climatic conditions, pest and pathogen control, and agricultural production on maintenance research expenditures are tested in the long and short run. Each category has a statistically significant impact on maintenance research expenditures.