The agricultural sector has operated in a period of high real interest rates for over half a decade. Some are concerned that this has limited capital availability and stagnated the historic capital for labor substitution occurring in the sector. This study proposes new procedures for estimating the aggregate production function of United States agriculture. Improvements include incorporation of total returns and revised measures of both durable and nondurable capital inputs. Results indicate increasing capital productivity has occurred, but encouraging further capital substitution may not benefit agricultural producers.