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Finely divided carbon char products offer a cost-effective method for the safening of herbicides in soil. In this investigation, two contrasting carbon char sources: Virgin Activated Charcoal (VAC) and Recovered Carbon Black (RCB) products were evaluated for safening of metsulfuron, sulfentrazone and pyroxasulfone herbicides in soil using sugar beet bioassay, and of rimsulfuron using perennial ryegrass bioassay. Plants were grown for seven days in WhirlPack® bags in soil with added carbon char product and added herbicide, and the root or shoot lengths were measured. The VAC was more efficacious in herbicide safening than the RCB. For the VAC, concentrations in soil (wt/wt) as low as 0.375% fully deactivated metsulfuron, sulfentrazone and pyroxasulfone, while for the RCB product a gradual degree of safening was observed, except for pyroxasulfone that was completely deactivated by both VAC and RCB. The VAC at concentrations of 3% and above fully deactivated rimsulfuron, while RCB did not. The two carbon char products examined in this study had different physical properties, of which the specific surface area (91 and 515 m2 g−1 for the RCB and VAC, respectively) and specific surface area of pores (75 and 247 m2 g−1 for RCB and VAC, respectively) showed the greatest difference. Higher surface area promoting greater sorption may explain more effective deactivation of herbicides by the VAC. To obtain the same degree of herbicide safening, more RCB would be required. [ABSTRACT FROM AUTHOR]

An interactive web‐based model (https://norstar.usask.ca/survivalmodel) that simulates winter survival in cereals has been developed for use by farmers, extension workers, plant breeders, and researchers. Consistent with our current understanding of low‐temperature (LT) gene regulation, the model is based on a series of equations describing phenological development, acclimation, dehardening, and damage due to LT stress. Low‐temperature tolerance is estimated on a daily basis relative to crown temperature, stage of phenological development, and cultivar LT tolerance potential. Acclimation proceeds until the start of the reproductive growth stage, which becomes a critical developmental switch that initiates the downregulation of LT tolerance gene expression. Environmental data can be uploaded and model input parameters revised to allow for simulation of genotypic differences and environmental conditions of special interest to users. Because the model is fully interactive, it can be used as a teaching tool that allows production risks, cause‐and‐effect processes, and genetic theories to be systematically investigated. In addition to encouraging more widespread use of the model, opening access to interested researchers will serve as a means of additional testing and validation allowing further refinements to be made. This will hopefully lead to increased prediction accuracy over a wider range of environmental conditions and a better understanding of the dynamic interactions involved in over‐winter survival of winter annual crops. [ABSTRACT FROM AUTHOR]

During the early establishment phase, outplanted white spruce (Picea glauca (Moench) Voss) and jack pine (Pinus banksiana Lamb.) seedlings are vulnerable to lethargic growth or mortality because of interspecific competition for soil nutrients, particularly N. Accurately quantifying the degree of N competition is essential for supporting effective vegetation management (VM) decisions. This study evaluated the use of in situ burials of ion-exchange membrane (IEM; Plant Root SimulatorTM-probes) for quantifying differences in soil N supply rate between different VM treatments and the relationship of this N availability index to early growth of conifer seedlings at four boreal forest sites. At most sites, the effect of noncrop N uptake on soil N availability was apparent, with smaller NH4+-N, NO3–-N, and total dissolved inorganic N (DIN) supply rates in control plots than in VM plots. Total DIN supply rate was correlated (R2 = 0.60 to 0.73, P < 0.01) with seedling height, root-collar diameter, and stem volume growth. Ammonium-N supply rate was better correlated than NO3–-N supply rate with conifer seedling growth, which is in agreement with preferential NH4+-N uptake by conifer species. The results of this study support the use of in situ burials of IEM for measuring soil N availability during the early establishment phase. [ABSTRACT FROM AUTHOR]