Six field trials were conducted over a two-year period (2014, 2015) to determine the level and consistency of glyphosate-resistant (GR) Canada fleabane control with glyphosate plus saflufenacil plus a third tankmix partner. GR Canada fleabane interference reduced soybean yield 73% compared with the weed free control. At 4 and 8 weeks after application (WAA), glyphosate plus saflufenacil provided 99% and 88% control of GR Canada fleabane respectively, and at 8 WAA, reduced GR Canada fleabane density by 96% and biomass by 89%. Glyphosate plus saflufenacil plus dicamba improved the control of GR Canada fleabane to 100% and 97% at 4 and 8 WAA, respectively. At 8 WAA, glyphosate plus saflufenacil plus amitrole reduced GR Canada fleabane density and biomass 99% and 97%, respectively. At 8 WAA, glyphosate plus saflufenacil plus dicamba at 300 or 600 g a.i. ha −1 reduced GR Canada fleabane biomass 97% and 98%, respectively. Tank-mixing dicamba with glyphosate plus saflufenacil applied pre-plant improved control of GR Canada fleabane; however, this caused 14% and 46% crop injury at 2 and 4 WAA, respectively. Soybean yield for saflufenacil alone and saflufenacil tankmix treatments were similar to the weed free control, with the exception of dicamba (600 g a.i. ha −1).
This second model was calibrated with data from an 8-day ambient-temperature injection test at 18.9 L/s. Boundary-flux conditions were examined for nonisothermal conditions by simulating 8 days of injection of 150 °C water at 18.9 L/s. Results of simulations using both models indicate that the flux-boundary conditions are adequate for simulations of short-term heat-injection testing.
The U.S. Geological Survey is modeling hydraulic flow and thermal‐energy transport at a two‐well injection/ withdrawal system in St. Paul, Minnesota. The design of the finite‐difference model grid for the doublet‐well system is complicated because the aquifer is anisotropic and the principal axes of transmissivity are not aligned with the axis between the two wells.
An analytical solution for flow in a doublet‐well system in an infinite anisotropic aquifer was employed in the design of a grid with artificial boundaries placed in the midst of the flow field. Flow‐net analysis was used to determine water flux across an cquipotential boundary and to assign approximate flux values at model boundaries. This enabled the simulation of the effects of the entire flow field, although only a small part was modeled.
The validity of the flux values at the model boundaries for the isothermal case was tested by simulation of an eight‐day injection test of ambient‐temperature water. Model‐computed pressures compared very favorably with field‐observed pressures. The validity of boundary‐flux values also was tested for nonisothermal conditions by simulation of injection of 300o F water at 300 gallons per minute for eight days.
The U.S. Geological Survey is studying the potential for storage of heated water in a sandstone aquifer in St. Paul, Minnesota. The efficiency of the aquifer to store thermal energy is related, in part, to the hydrogeologic characteristics of the aquifer. The movement of heat away from the injection well is directly related to the anisotropy. Aquifer tests were conducted to determine the anisotropy near the heated‐water injection well. The maximum and minimum values of transmissivity along the principal directions of the hydraulic conductivity tensors of the Ironton and Galesville Sandstones in St. Paul, Minnesota are approximately 1,090 and 480 feet squared per day. The storage coefficient is 4.5 × 10−5. These values represent the average of four determinations of nonsteady flow to a well in an idealized infinite anisotropic aquifer. Analysis of the values of transmissivity and storage coefficient for hypothetical changes in location of two of the monitoring wells where depth‐deviation surveys were not available indicates that computed transmissivities vary less than 5 percent and storage coefficients vary less than ±6 percent.
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