Estimating Uncertainty of Economically Optimum N Fertilizer Rates

Figure 4

All measured values (including the zero 𝑁 rate) as fitted by the linear-plus-plateau model and confidence sets for 𝑁_opt in both yield zones of the Sieblerfeld trials, where the ratio between 𝑁 fertilizer price 𝑟 and crop price 𝑝 is 𝑟⋅𝑝⁻¹=5.4545, for example, 𝑟=0.60€kg⁻¹ and 𝑝=110€Mg⁻¹.