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在宾夕法尼亚州乞沙比克湾流域,通常用微机模型CREAMS来评价最优田间管理措施(简称BMPs)及肥力管理方案(简称NMPs)对三个区域中3种不同土地的泥沙和养分损失量的影响效果。对若干种BMPs进行了评价,同时与BMPs结合起来评价了两种不同的NMPs,一种为传统的施肥措施,另一种是改进的高效管理系统(该系统使时间、地点及各种养分得到有效的组合)。与没有保护措施用有壁犁耕作的条件相比,BMPs能增加渗透、减少径流,而且能减少泥沙输移。氮(N)和磷(P)总损失量的降低,随不同的BMPs及地点而变化。虽然BMPs能减少泥沙中的N、P含量,但与常规的NMPs相比,改进的NMPs相对来说对其损失量的影响极小。BMPs将增加硝酸盐的淋溶量,而改进的NMPs则能相当大地降低由可溶性P流失占主要成分地区的P损失。BMPs与NMPs两项同时配合使用,则能有效地降低泥沙及养分的损失量。
In the Chesapeake Bay Basin, Pennsylvania, computer-aided modeling (CREAMS) is commonly used to evaluate the effects of optimal field management practices (BMPs) and fertility management programs (NMPs) on sediment and nutrient losses in three different areas of the three regions Effect of the effect. Several BMPs were evaluated and at the same time, two different NMPs were evaluated in combination with BMPs, one for conventional fertilization measures and the other for an improved and efficient management system (which allows time, place and various nutrients to be obtained Effective combination). BMPs can increase infiltration, reduce runoff, and reduce sediment transport compared to plowing without plowing. The total loss of nitrogen (N) and phosphorus (P) decreases with different BMPs and sites. Although BMPs can reduce the N and P content in sediment, the modified NMPs have relatively little impact on the loss compared with the conventional NMPs. BMPs will increase the leaching of nitrate, while the modified NMPs will considerably reduce the P loss in regions where soluble P is lost as the major component. BMPs and NMPs used in conjunction with the two at the same time, it can effectively reduce the loss of sediment and nutrients.