To establish the optimum barium-based reduced-laxative tagging regimen prior to CT colonography (CTC). Ninety-five subjects underwent reduced-laxative (13 g senna/18 g magnesium citrate) CTC prior to same-day colonoscopy and were randomised to one of four tagging regimens using 20 ml 40%w/v barium sulphate: regimen A: four doses, B: three doses, C: three doses plus 220 ml 2.1% barium sulphate, or D: three doses plus 15 ml diatriazoate megluamine. Patient experience was assessed immediately after CTC and 1 week later. Two radiologists graded residual stool (1: none/scattered to 4: >50% circumference) and tagging efficacy for stool (1: untagged to 5: 100% tagged) and fluid (1: untagged, 2: layered, 3: tagged), noting the HU of tagged fluid. Preparation was good (76-94% segments graded 1), although best for regimen D (P=0.02). Across all regimens, stool tagging quality was high (mean 3.7-4.5) and not significantly different among regimens. The HU of layered tagged fluid was higher for regimens C/D than A/B (P=0.002). Detection of cancer (n=2), polyps ≥6 mm (n=21), and≤5 mm (n=72) was 100, 81 and 32% respectively, with only four false positives ≥6 mm. Reduced preparation was tolerated better than full endoscopic preparation by 61%. Reducedlaxative CTC with three doses of 20 ml 40% barium sulphate is as effective as more complex regimens, retaining adequate diagnostic accuracy.

The equivalent retention of Ca2+ and SO2‐4 from gypsum solutions in acid subsoils has recently been reported. The term salt sorption has been coined to describe this process, yet little is known about the nature of the reactions involved. This study was conducted to determine if other cation‐anion combinations would exhibit similar behavior and to examine the extractability of the sorbed ions. An unfertilized acid Cecil (clayey, kaolinitic, thermic Typic Kanhapludult) subsoil was equilibrated using a saturated paste technique, with solutions of six different salts at a loading rate of ≈14.0 mmolc kg‐1. The salt solutions used were CaSO4, MgSO4, Na2SO4, CaCl2, MgCl2, and a deionized water control. This soil exhibited salt sorption with all six electrolyte solutions. The SO4 salts were almost completely sorbed with both cation and anion uptake on the order 13.8 mmolc kg‐1. Calcium and magnesium chloride were sorbed at ≈11.7 mmolc kg‐1, and NaCl was sorbed at 8.2 mmolc kg‐1. The treated soils were air dried and extracted with successive portions of deionized water or 0.5 M NH4NO3. A relatively large proportion of both cations and anions were removed by repeated extraction with water, suggesting that ionic strength played an important role in the salt sorption process. Nearly all of the sorbed cations and Cl‐ were recovered by neutral salt extraction, but <100% of the SO2‐4 could be accounted for by neutral salt extraction. Neutral salt extractable Al was significantly reduced by salt treatment. It appeared that salt sorption in this soil may have resulted from several mechanisms including precipitation, specific adsorption, ionic strength induced charging, and ion pair adsorption operating concurrently.

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Weed management in tobacco (Nicotiana tabacumL.) is accomplished primarily with soil-residual herbicides, cultivation, and hand removal. Management practices that reduce weed emergence, like reduced tillage and cover crop mulches, may improve weed management efficacy. Depending on cover-cropping goals, growers face trade-offs in species selection and management priorities—producing weed-suppressive mulches may lead to transplanting difficulties and soil-residual herbicide interception. Managing more complex cover crop mixtures may result in different challenges. We established on-farm trials across 4 site-years to study impacts of cover crop composition [wheat (Triticum aestivumL.) monoculture or mixture], termination treatment (early or late chemical termination or removing aboveground biomass), and soil-residual herbicides on weed density and biomass. The cover crop mixture contained cereal rye (Secale cerealeL.), crimson clover (Trifolium incarnatumL.), and hairy vetch (Vicia villosaRoth.), with canola (Brassica napusL.) at 1 site-year. The mixture typically produced more biomass than monoculture wheat, although composition had few impacts on weed density or biomass. With residual herbicides, termination treatment had few impacts on weed density, suggesting that residues did not adversely affect herbicide efficacy. Without residual herbicides, early-season weed density was often higher following the late-terminated cover crop compared with other termination treatments, though midseason weed density was typically lower. When termination treatment affected final weed biomass, it was lower following late termination, with one exception—crop establishment was reduced at 1 site-year, leading to reduced weed–crop competition and greater weed biomass. Our results suggest that growers can use mixtures and, if well-timed to a rainfall event for incorporation, still effectively use soil-residual herbicides to maintain adequate weed control in tobacco regardless of how the cover crop is managed. Later termination, resulting in more residue, may lead to less weed biomass accumulation in the absence of herbicide use.