AN ECONOMIC-ANALYSIS OF REDUCING NITROGEN ON EARLY HARVEST SUGAR-BEETS

Both sugarbeet (Beta vulgaris L.) producers and sugar processors have interests in lengthening the harvest and processing season by harvesti ng a certain percentage of sugarbeet acreage earlier in the year. As a general practice, many growers have not adjusted their rates of N on acres intended for earlier harvest. Previous research has shown benefi ts of increased production from reducing the rate of N on acreage plan ned for earlier harvest. However, similar benefits of increased profit ability were not considered. This study was designed to examine the ec onomic benefit of reducing N on acreage intended for earlier harvest. A response function was estimated from three years (1988-1990) of fiel d trials at the University of Wyoming Powell Research and Extension Ce nter to relate net return from sugarbeets to (i) the amount of N/acre (0-300 lb) and (ii) selected date of harvest (from 10 September-24 Oct ober). For each of the 45 harvest dates (10 September-24 October), the optimal (highest profit) rate of N was identified. A fourth year of f ield data (1991) was then used to test the predictive performance of t he estimated function. As opposed to simply applying N at a constant r ate of 200 lb/acre (with no regard to time of intended harvest), reduc ing the rate of N by 12 to 14 lb/acre for each week of earlier harvest increased net return in the early (September) harvest season. Specifi cally, the increase in net return (from lower rates of N) ranged from $5/acre for sugarbeets harvested in late September (24-30 September), to $14/acre for sugarbeets harvested in early September (10-16 Septemb er).