Fig. 4. Curves used to estimate stover collection cost as a function of stover collected in the field. Curves include $7.17 Mg^–1 nutrient replacement cost ($6.50 ton^–1) (Gallagher et al., 2003). "Bale windrow" refers to the collection method assumed to be used when collecting less than 2.69 Mg ha^–1. "Rake/windrow & bale" refers to the method assumed used when collecting between 2.69 and 3.36 Mg ha^–1. "Two operations–Shred/rake and bale" refers to the method assumed used when collecting greater than 3.36 Mg ha^–1. The three methods are described in Table 2.