A cooled double crystal monochromator system is used on many high heat load X-ray synchrotron radiation beamlines in order to select, by diffraction, a narrow spectrum of the beam. Thermal deformation of the first crystal monochromatorand the potential loss of beam brightnessis often a concern. However, if downstream beam focusing is planned, the lensing effect of the monochromator must be considered even if thermal deformations are small. In this paper we report on recent experiments at an Advanced Photon Source (APS) beamline that focuses the X-ray beam using compound refractive lenses downstream of an X-ray monochromator system. Increasing the X-ray beam power by increasing the storage ring current from 100 mA to 130 mA resulted in an effective doubling of the focal distance. We show quantitatively that this is due to a lensing effect of the distorted monochromator that results in the creation of a virtual source downstream of the actual source.An analysis of the defocusing and options to mitigate this effect are explored.

Recent increases in corn (Zea mays L.) production in the U.S. Corn Belt have necessitated the conversion of rotations to continuous corn, and an increase in the frequency of tillage. e objective of this study was to assess the e ect of rotation and tillage on soil physical and chemical properties in soils typical of Illinois. Sequences of continuous corn (CCC), 2-yr corn-soybean [Glycine max (L.) Merr.] (CS) rotation, 3-yr corn-soybean-wheat (Triticum aestivum L.) (CSW) rotation, and continuous soybean (SSS) were split into conventional tillage (CT) and no-till (NT) subplots at two Illinois sites. A er 15 yr, bulk density (BD) under NT was 2.4% greater than under CT. Water aggregate stability (WAS) was 0.84 kg kg -1 under NT compared to 0.81 kg kg -1 under CT. Similarly, soil organic carbon (SOC) and total nitrogen (TN) were greater under NT than under CT with SOC values for 0 to 60 cm of 96.0 and 91.0 Mg ha -1 and TN values of 8.87 and 8.40 Mg ha -1 for NT and CT, respectively. Rotations a ected WAS, TN, and K levels with WAS being greatest for the CSW rotation at 0.87 kg kg -1 , decreasing with more soybean years (CS, 0.82 kg kg -1 and SSS, 0.79 kg kg -1 ). A similar pattern was detected for TN and exchangeable K. Results indicated that while the use of NT improved soil quality, long-term implementation of continuous corn had similar soil quality parameters to those found under a corn-soybean rotation.

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Soil health indicator values vary based on parent material, native vegetation, and other soil forming factors; therefore, useful interpretations require consideration of inherent soil characteristics. Our objective was to evaluate the distribution of soil health indicators across soil and climate gradients throughout the state of Missouri through a statewide cover crop cost‐share program. Soil samples (0–7 cm) were collected from 5,300 agricultural fields and analyzed for several soil health indicators. Comparisons were made among six regions in the state based on Major Land Resource Area and county boundaries. Results varied for soil organic carbon (C), active C, potentially mineralizable nitrogen, water stable aggregates, and cation exchange capacity by region and corresponded with soil forming factors. Interpretation of soil health indicators must account for regional factors, recognizing that areas with different inherent values have a different potential for soil health.

Abstract:Crop rotation and tillage alter soil organic matter (SOM) dynamics by influencing the soil environment and microbes carrying out C and N cycling. Our goal was to evaluate the effect of long-term crop rotation and tillage on the quantity of C and N stored in SOM and microbial biomass. Two experimental sites were used to evaluate four rotations-continuous corn (Zea mays L.) (CCC), corn-soybean (Glycine max [L.] Merr.) (CS), corn-soybean-wheat (Triticum aestivum L.) (CSW), and continuous soybean (SSS), each split into chisel tillage (CT) and no-till (NT) subplots. The CSW rotation increased soil organic carbon (SOC) content compared to SSS; SSS also reduced total nitrogen (TN) compared to other rotations. Levels of SOC and TN were 7% and 9% greater under NT than CT, respectively. Rotation did not affect microbial biomass C and N (MBC, MBN) while tillage reduced only MBN at 10-20 cm compared to NT, likely related to dispersion of N fertilizers throughout the soil. Despite the apparent lack of sensitivity of microbial biomass, changes in SOC and TN illustrate the effects of rotation and tillage on SOM dynamics. The inclusion of crops with high C: N residues and no-till use both support higher C and N content in the top 20 cm of the soil.

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The Missouri Soil and Water Conservation Program was initiated by the Department of Natural Resources (DNR) to address challenges related to soil and water degradation by examining soil health under real-world management practices. Soil health data from 5,300 field sites enrolled in a DNR cost-share program were analyzed for the effects of tillage intensity [no-till (NT), reduced tillage (RT), and intensive tillage (IT)] and crop rotational diversity (monoculture, two-crops, and three or more crops in rotation) within and across six regions in the state. Soil health indicators included soil organic carbon (SOC), active carbon, potentially mineralizable nitrogen (PMN), and aggregate stability. At the state level, SOC, active carbon, and PMN were 14.4, 14.0, and 17.5% greater under NT, and 10.2, 11.0, and 11.2% greater under RT, respectively, compared with IT. Aggregate stability was greater under NT (33.8%) and RT (30.4%) relative to IT (28.0%). Across the state, diversified rotations with three or more crops exhibited 6.1 and 7.9% greater SOC, 6.5 and 7.9% greater active carbon, and 10.7 and 11.6% greater PMN relative to two-crop rotations or monocultures, respectively. Aggregate stability was significantly greater under diversified rotations (35.5%) relative to two-crop rotations (30.6%) and monoculture (30.8%). This study highlights the value of on-farm datasets from real crop production systems and illustrates the potential to increase soil health with adoption of conservation tillage and extended crop rotations in Missouri.