A row crop unit for use in an agricultural seeder includes a furrow opener for opening a furrow in the soil, a seed metering system for metering seed to be placed in the furrow, and a seed placement system for placing seeds in the furrow. The seed placement system and the seed metering system are in communication with each other and at least in part define a seed travel path associated with the furrow. A furrow closer covers the seed in the furrow with soil. A seed temperature conditioner is associated with the seed travel path for varying a temperature of seed traveling through the seed travel path. A temperature sensitive sensor is positioned to sense seed which has been deposited in the furrow between the furrow opener and the furrow closer. An optional packaging tube holds a temperature sensor or sensor array. A lens is mounted with the same tube. A larger diameter tube may be positioned around the sensor packaging tube. A positive air pressure/air flow may be introduced between the two tubes. This positive air-flow forms a positive pressure and/or air flow barrier to push dust away from the sensor lens or sensor surface.
