The impact of organic and conventional crop management together with two variations of conservation tillage was evaluated on N supply and losses at the end of a 4-year Swiss crop rotation. Soil samples were taken from four cropping systems: conventional intensive tillage (C-IT), conventional no tillage (C-NT), organic intensive tillage (O-IT) and organic reduced tillage (O-RT). Laboratory incubations were used to estimate rates of net mineralization, gross nitrification and potential denitrification, while quantitative PCR was used to determine copy numbers of genes of relevant enzymes in these processes. N supply via mineralization and nitrification was unaffected by cropping system. Significant decrease in bacterial ammonia oxidizer (AOB) abundance at the end of the gross nitrification incubation indicated greater responsiveness of this group for activity, in particular under conventional management. C-NT produced the highest potential denitrification, although only significantly different than C-IT. O-RT was similar to C-IT and C-NT in terms of soil N supply and N gaseous losses, meaning that added benefits through its use does not compromise plant N availability or increase N2O losses compared to conventional practices.

中文翻译：

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有机减耕和常规集约耕作下细菌介导的氮供应和损失的可比性

在 4 年瑞士作物轮作结束时，对有机和传统作物管理以及两种保护性耕作方式对氮供应和损失的影响进行了评估。土壤样品取自四种耕作系统：常规集约耕作（C-IT）、常规免耕（C-NT）、有机集约耕作（O-IT）和有机减耕（O-RT）。实验室孵化用于估计净矿化、总硝化和潜在反硝化的速率，而定量 PCR 用于确定这些过程中相关酶基因的拷贝数。通过矿化和硝化作用提供的氮不受种植制度的影响。在总硝化培养结束时细菌氨氧化剂 (AOB) 丰度的显着下降表明该组对活动的反应性更强，特别是在常规管理下。C-NT 产生了最高的反硝化潜力，尽管与 C-IT 仅显着不同。在土壤氮供应和氮气态损失方面，O-RT 与 C-IT 和 C-NT 相似，这意味着与传统做法相比，通过使用 O-RT 增加的好处不会影响植物氮的可用性或增加 N2O 损失。