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United States Department of Agriculture

Agricultural Research Service

Research Project: SOIL MANAGEMENT SYSTEMS FOR DRYLAND AND IRRIGATED CROPPING SYSTEMS

Location: Agroecosystem Management Research

Title: No-tillage increases soil profile carbon and nitrogen under long-term rainfed cropping systems

Authors
item Varvel, Gary
item Wilhelm, Wallace

Submitted to: Soil and Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 22, 2011
Publication Date: April 22, 2011
Citation: Varvel, G.E., Wilhelm, W.W. 2011. No-tillage increases soil profile carbon and nitrogen under long-term rainfed cropping systems. Soil and Tillage Research. Available: doi:10.1016/j.still.2011.03.005.

Interpretive Summary: Interest in carbon and nitrogen storage in soils has greatly increased in the last few years, especially with their potential to alleviate or offset some of the negative effects of the increase in greenhouse gases in the atmosphere. A long-term rainfed study comparing both the effects of different tillage treatments and cropping systems in eastern Nebraska provided the opportunity to determine their effects on total nitrogen and soil organic carbon storage. The study included six tillage treatments (chisel, disk, plow, no-till, ridge-till, and subtill) with three cropping systems (continuous corn and soybean, and soybean-corn). Soil samples were collected to a depth of 150-cm in depth increments of 0 to 15-, 15 to 30-, 30 to 60-, 60 to 90-, 90 to 120-, and 120 to 150-cm in the fall of 1999 after harvest and analyzed for total nitrogen and carbon. Total nitrogen and soil organic carbon levels differed between tillage treatments and cropping systems in all depth increments down to 60-cm. Total nitrogen and soil organic carbon accumulations throughout the profile were significantly affected by both tillage treatment and cropping system, with those in the no-till treatment the greatest among tillage treatments and those in continuous corn the greatest among cropping systems. Total nitrogen and soil organic carbon levels were significantly increased at deeper depths in the profile, especially in those tillage treatments with the least amount of soil disturbance. Most significant was the fact that total nitrogen and soil organic carbon was sequestered deeper in the profile than has been reported in most studies. The implication of these results is that total nitrogen and soil organic carbon stored at these depths would be less likely to be lost if the soil was tilled, enhancing their potential long-term benefits with respect to greenhouse gas amelioration.

Technical Abstract: Emphasis and interest in carbon (C) and nitrogen (N) storage (sequestration) in soils has greatly increased in the last few years, especially C with its’ potential to help alleviate or offset some of the negative effects of the increase in greenhouse gases in the atmosphere. Several questions still exist with regard to what management practices optimize C storage in the soil profile. A long-term rainfed study conducted in eastern Nebraska provided the opportunity to determine both the effects of different tillage treatments and cropping systems on soil N and soil organic C (SOC) levels throughout the soil profile. The study included six primary tillage treatments (chisel, disk, plow, no-till, ridge-till, and subtill) with three cropping systems [continuous corn (CC), continuous soybean (CSB), and soybean-corn (SB-C)]. Soil samples were collected to a depth of 150-cm in depth increments of 0 to 15-, 15 to 30-, 30 to 60-, 60 to 90-, 90 to 120-, and 120 to 150-cm and composited by depth in the fall of 1999 after harvest and analyzed for total N and SOC. Significant differences in total N and SOC levels were obtained between tillage treatments and cropping systems in both surface depths of 0 to 15-, 15 to 30-cm, but also in the 30 to 60-cm depth. Total N and SOC accumulations throughout the profile (both calculated by depth and for equivalent masses of soil) were significantly affected by both tillage treatment and cropping system, with those in no-till the greatest among tillage treatments and those in CC the greatest among cropping systems. Soil N and SOC levels were increased at deeper depths in the profile, especially in those tillage systems with the least amount of soil disturbance. Most significant was the fact that soil N and SOC was sequestered deeper in the profile, which would strongly suggest that N and C at these depths would be less likely to be lost if the soil was tilled. [GRACEnet Publication]

Last Modified: 8/22/2014
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