This document on the CMB-S4 Science Case, Reference Design, and Project Plan is the product of a global community of scientists who are united in support of advancing CMB-S4 to cross key thresholds in our understanding of the fundamental nature of space and time and the evolution of the Universe. CMB-S4 is planned to be a joint National Science Foundation (NSF) and Department of Energy (DOE) project, with the construction phase to be funded as an NSF Major Research Equipment and Facilities Construction (MREFC) project and a DOE High Energy Physics (HEP) Major Item of Equipment (MIE) project. At the time of this writing, an interim project office has been constituted and tasked with advancing the CMB-S4 project in the NSF MREFC Preliminary Design Phase and toward DOE Critical Decision CD-1. DOE CD-0 is expected imminently.CMB-S4 has been in development for six years. Through the Snowmass Cosmic Frontier planning process, experimental groups in the cosmic microwave background (CMB) and broader cosmology communities came together to produce two influential CMB planning papers, endorsed by over 90 scientists, that outlined the science case as well as the CMB-S4 instrumental concept [1, 2]. It immediately became clear that an enormous increase in the scale of ground-based CMB experiments would be needed to achieve the exciting thresholdcrossing scientific goals, necessitating a phase change in the ground-based CMB experimental program. To realize CMB-S4, a partnership of the university-based CMB groups, the broader cosmology community, and the national laboratories would be needed.The community proposed CMB-S4 to the 2014 Particle Physics Project Prioritization Process (P5) as a single, community-wide experiment, jointly supported by DOE and NSF. Following P5's recommendation of CMB-S4 under all budget scenarios, the CMB community started in early 2015 to hold biannual workshops -open to CMB scientists from around the world -to develop and refine the concept. Nine workshops have been held to date, typically with 150 to 200 participants. The workshops have focused on developing the unique and vital role of the future ground-based CMB program. This growing CMB-S4 community produced a detailed and influential CMB-S4 Science Book [3] and a CMB-S4 Technology Book [4]. Over 200 scientists contributed to these documents. These and numerous other reports, workshop and working group wiki pages, email lists, and much more may be found at the website http://CMB-S4.org.Soon after the CMB-S4 Science Book was completed in August 2016, DOE and NSF requested the Astronomy and Astrophysics Advisory Committee (AAAC) to convene a Concept Definition Taskforce (CDT) to conduct a CMB-S4 concept study. The resulting report was unanimously accepted in late 2017. 1 One recommendation of the CDT report was that the community should organize itself into a formal collaboration. An Interim Collaboration Coordination Committee was elected by the community to coordinate this process. The resulting draft bylaws were refined at the Spring 2018 CMB-S4...

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No‐tillage (NT) crop production practices have been continuously maintained at four sites in Ohio for more than 25 yr. The original experiments involving NT were designed to determine how much tillage was required to produce crops with satisfactory yields and how tillage and rotation interact to effect crop yields, especially corn (Zen mays L.). Long‐term effects of NT on crop yields and soil properties are generally not known because few sites exist with histories of ≥20 yr of NT. This paper reports yield trends of corn and soybean [Glycine max (L.) Merr.] and changes in soil properties that occurred when NT was continuously practiced on soils in Ohio. Significantly lower yields for NT, as compared to conventional tillage (CT), were observed for monoculture corn and for soybean in rotation during the first 18 yr on a very poorly drained Mollic Ochraqualf soil. The yield differences observed for corn could be largely eliminated by crop rotation and for soybean by the use of phytophthera resistant/tolerant soybean cultivars. On a well‐drained Typic Fragiudalf soil, crop yields were always higher with NT than with CT. After 18 yr, yield trends indicated the negative impact of NT on the very poorly drained soil was greatly decreased and the yield advantages associated with NT on the well‐drained soil became even more pronounced. The change in yield trends did not appear to be associated with change in weather patterns. The long‐term NT sites also revealed organic matter, nutrients, and soil enzymes accumulated at the soil surface but decreased deeper (>20 cm) in the soil profile. Surface water runoff was found to be greatly decreased from the long‐term NT watershed site (≈9% slope) with only 12 mm of runoff measured between 1979 and 1985.