Estimating Uncertainty of Economically OptimumNFertilizer Rates

[摘要] Nitrogen rate trials are often performed to determine the economically optimumNapplication rate. For this purpose, the yield is modeled as a function of theNapplication. The regression analysis is commonly used to estimate the modeled functions and the economic optimum rate,Nopt. However, computer programs do not calculate confidence intervals forNoptderived from quadratic yield response model or other commonly used models. The objective was to develop a method for computing and interpreting confidence intervals forNopt. These confidence intervals can be estimated using an online program VINO.EXE. For theNrate trials on the experimental field Sieblerfeld (Bavaria), confidence intervals were computed for a range of wheat andNfertilizer prices and for selectedNrates for quadratic and linear plateau models. The latter concerns the comparison with confidence intervals based upon the linear-plus-plateau yield regression model. All intervals were found to be unexpectedly wide and their ranges were affected byNrates used in the calculations and by the choice of yield response model.

[学科分类] 农艺学与作物科学