Kansas State University, Agricultural Research Center-Hays, 1232 240th Ave., Hays, KS 67601, USA.
J Environ Qual. 2009 Oct 29;38(6):2365-72. doi: 10.2134/jeq2009.0021. Print 2009 Nov-Dec.
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%.
作物残茬的移除（例如扩大用作纤维素乙醇生产的原料）可能会增加流失的泥沙和养分。我们评估了可变残茬移除率对堪萨斯州西部免耕冬小麦（Triticum aestivum L.）和犁耕谷子[ Sorghum bicolor (L.) Moench]种植的泥沙、土壤有机碳（SOC）和养分流失的田间影响。在两种耕作水平下（免耕和新耕），为小麦和谷子（春季耕和新耕）设立了五个处理，每个处理有三个重复，包括收获后分别以 0、25、50、75 和 100%的残茬移除率，每个处理的面积为 1x2 m。在 115+/-3 mm h(-1) 的模拟降雨下，持续 30 分钟。与无残茬移除的处理相比，在新耕的小麦处理中，完全移除增加了 61%的径流量；在春季耕的谷子处理中，增加了 225%；在新耕的谷子处理中，增加了 94%。即使残茬移除率低至 50%，也会增加泥沙流失。在耕小麦中，完全移除会使泥沙流失增加一倍，达到 14 Mg ha(-1)；而在免耕小麦中，泥沙流失从 0.9 增加到 7.2 Mg ha(-1)。无耕 100%的残茬移除流失的泥沙量与新耕小麦中 0%或 25%的残茬移除流失的泥沙量一样多。75%和 100%的残茬移除增加了与泥沙相关的总氮、总磷和 SOC 的损失。总的来说，过度的残茬移除导致了大量的泥沙、泥沙结合的 SOC 和养分在径流下流失。此外，当残茬移除率超过 25%时，免耕管理提供的侵蚀保护就会丧失。
