Response of a New Colorado Russet Potato Cultivar to Nitrogen Application Timing.

Nitrogen fertilizer application timing is one of the most important management techniques that potato growers can use to increase N Use Efficiency, and improve tuber yield and quality.  Potato cultivars vary in their response to nitrogen fertilizer application timing.  Field studies were conducted at the San Luis Valley Research Center, Colorado State University, USA, to evaluate the response of Crestone Russet, a new Colorado Russet potato cultivar, to nitrogen fertilizer application timing.  Nitrogen fertilizer application timing treatments included the application of 33% of the required nitrogen fertilizer (N) pre-plant; 50% of the required N pre-plant; and 66% of the required N pre-plant.  The remaining required N was applied in-season, in split applications.  A control treatment was established where all the required N was applied pre-plant.  The total amount of N applied to each treatment was 140 lb N/Acre. Leaf Area Index (LAI) at 93 days after planting was observed to be highest (4.3) when 33% or 50% of the required N was applied pre-plant. Total and marketable tuber yield was highest (468 and 397 cwt/acre, respectively) when 33% of the required N was applied pre-plant.  Data from this study indicate that to maximize N Use Efficiency in a medium maturity potato cultivar such as Crestone Russet, specific N application timing techniques have to be followed.