title: Wheat and sorghum residue removal for expanded uses increases sediment and nutrient loss in runoff.
abstract: Crop residue removal for expanded uses such as feedstocks for cellulosic ethanol production may increase loss of sediment and nutrients in runoff. We assessed on-farm impacts of variable rates of residue removal from no-till winter wheat (Triticum aestivum L.) and plow till grain sorghum [Sorghum bicolor (L.) Moench] on sediment, soil organic carbon (SOC) and nutrient losses in runoff in western Kansas. Five treatments with three replications consisting of removing residues at 0, 25, 50, 75, and 100% after harvest under two tillage levels for wheat (no-till and freshly tilled) and grain sorghum (spring tilled and freshly tilled) were established on 1x2 m plots. Simulated rainfall was applied at 115+/-3 mm h(-1) for 30 min. Compared with plots without residue removal, complete removal increased runoff by 61% in freshly tilled wheat plots, 225% in spring-tilled sorghum plots, and 94% in freshly tilled sorghum plots. Residue removal at rates as low as 50% increased loss of sediment. Complete removal doubled the sediment loss to 14 Mg ha(-1) in tilled wheat, whereas it increased sediment loss from 0.9 to 7.2 Mg ha(-1) in no-till wheat. No-till with 100% residue removal lost as much sediment as freshly tilled wheat plots with 0 or 25% removal. Residue removal at 75 and 100% increased losses of total N, total P, and SOC associated with sediment. Overall, excessive residue removal led to large losses of sediment, sediment-bound SOC, and nutrients in runoff. Furthermore, erosion protection provided by no-till management is lost when residue removal exceeds 25%.
authors.affiliation: Kansas State University, Agricultural Research Center-Hays, 1232 240th Ave., Hays, KS 67601, USA. hblanco@ksu.edu
authors.forename: Humberto
authors.initials: H
authors.lastname: Blanco-Canqui
authors.forename: R J
authors.initials: RJ
authors.lastname: Stephenson
authors.forename: N O
authors.initials: NO
authors.lastname: Nelson
authors.forename: D R
authors.initials: DR
authors.lastname: Presley
mesh_terms: D000383:Agriculture / Q000379:methods*; D004787:Environmental Pollution; D019015:Geologic Sediments / Q000032:analysis; D007615:Kansas; D009930:Organic Chemicals / Q000032:analysis*; D011891:Rain; D012987:Soil / Q000032:analysis*; D045868:Sorghum; D014908:Triticum
chemical_list: D009930:Organic Chemicals; D012987:Soil