Nitrogen Fertility Does Not Affect Sugarbeet Storage Quality in Large Outdoor Piles.

Once harvested, the majority of Ontario sugarbeets are stored outside, typically over 120 days, in large piles until processed to extract raw white sugar.  Little is known about the impact of N fertility on sugarbeets storage losses in large outdoor piles.   In 2007 and 2008, a randomized complete block design field experiment was established to determine if N rate (0-225 kg N ha^-1) and timing (preplant vs. split) influenced sugarbeet recovery and quality during long term storage.  At harvest, representative beet samples from each treatment were weighed, placed in mesh bags within a large commercial storage pile, retrieved on each of three dates over the winter and analyzed for pile recovery (weight loss, % rots), quality (% sugar, % clear juice purity) and impurities (NH₂, amino-N).  Quality and yield data were used to determine recoverable white sugar per ton (RWST), recoverable white sugar per acre (RWSA) and grower payment (based on treatment yield and treatment RWST as a percent of company average).  In two contrasting growing seasons (dry vs. average), the optimal N rate for sugarbeets based on RWSA and grower payment ($ ac^-1), was approximately 110 kg N ha^-1.  Both storage seasons were ideal with <1% rots and <5.7% weight loss observed.  As expected, sugarbeet quality parameters and calculations were higher at harvest than at the last retrieval date (≥100 days).  Although there were differences between N treatments in root %N and total N content there was no interaction between N rate and storage date, for all parameters measured.  Thus, under ideal storage conditions, N fertilization does not influence the ability to store sugarbeets in large outdoor piles.