Two field scale studies were performed in five corn fields across southwest Michigan over three years in order to examine i) the influence of delayed corn plant emergence on final yield, and ii) the effect of strategic, varied nitrogen management on final yield, profit, and nitrogen use efficiency. Individual corn plant emergence date was documented, and kernel weight, kernel number, and biomass weights were analyzed in order to examine the importance of uniform plant stands in achieving high yields, analyzed by the known historical yield stability (Basso et al., 2019). The results showed a 22-gram decrease from early to late emergence and a 15-gram decrease in total kernel weight from early to medium emergence date, equivalent to 1,825 and 1,244 kg/ha decrease in yield. Yield stability zones differentiation showed a 19.9-gram decrease in relative total kernel weight (1,651 kg/ha) from historically high and stable yield to low and stable yield. More variability in days after planting and decreased yields were seen in the low and medium yielding zones. For the second field study, a procedure was created to variably rate nitrogen fertilization using remotely sensed imagery and crop modelling using the SALUS crop model. Whole plant destructive samples and yield monitor data were analyzed to examine the spatial and temporal variability in differing yield stability zones among all study sites. The results showed no statistically significant difference in yield or profit between nitrogen fertilization zones in most fields, while increases in nitrogen use efficiency were seen in all tactically reduced fertilization rate zones.
Read
