Nitrogen transport from agriculture production fields raises the specter of environmental degradation of freshwater resources. Our objectives were to document and evaluate nitrate-N, ammonium-N, phosphorus and other n...Nitrogen transport from agriculture production fields raises the specter of environmental degradation of freshwater resources. Our objectives were to document and evaluate nitrate-N, ammonium-N, phosphorus and other nutrients emanating from a 40-ha controlled subsurface irrigation drainage technology coupled in series with a denitrification bioreactor. The intent of the denitrification bioreactor is to create an environment for anoxic microbial populations to support denitrification. We monitored the tile-drainage effluent and denitrification bioreactor water chemistry under a corn-soybean rotation to estimate the nutrient concentrations and the competence of the denitrification bioreactor to foster denitrification. Nitrate-N bearing tile drainage effluents ranged from less than 1.5 to 109 mg NO3- -N/L, with the nitrate concentration differences attributed primarily to the: 1) timing of nitrogen fertilization for corn, 2) soil mineralization and residue decomposition, and 3) intense rainfall events. The denitrification bioreactor was highly effective in reducing drainage water nitrate-N concentrations providing the rate of water flow through the denitrification bioreactor permitted sufficient time for equilibrium to be attained for the nitrate reduction reactions. The nitrate-N concentrations entering the denitrification bioreactor ranged from 0.4 to 103 mg NO3-?-N/L in 2018, whereas the outlet nitrate concentrations typically ranged from 0.3 to 5.2 mg NO3- -N/L in 2018. Nitrate tile-drainage effluent concentrations in 2019 were marginal, given soybeans obtain nitrogen from biological nitrogen fixation. Nutrient uptake by corn reduced the soil nitrate leaching pool and created nitrogen-bearing biomass, features important for formulating best management practices.展开更多
There can be little argument that embryo quality is one of the most critical factors in the success of assisted reproductive techniques. Yet the current methods of grading embryos are subjective at best. While a numbe...There can be little argument that embryo quality is one of the most critical factors in the success of assisted reproductive techniques. Yet the current methods of grading embryos are subjective at best. While a number of different groups have described more qualitative means of assessing embryo quality, the current standard remains morphology. Morphology has proven a good standard, but it does not allow for the detection of chromosomal abnormalities nor can it assess the biochemical status of the embryo prior to transfer. This laboratory recently described a method to estimate embryo weight and suggested weight might be a good indicator of biochemical status. The objective of the present study was to determine the relationship between maternal body composition and embryo weight and determine the influence maternal chemistry had on embryo development. The data continue to suggest that maternal body composition, especially body fat, influences the chemical nature of the embryo and may play a critical role in long-term survival.展开更多
文摘Nitrogen transport from agriculture production fields raises the specter of environmental degradation of freshwater resources. Our objectives were to document and evaluate nitrate-N, ammonium-N, phosphorus and other nutrients emanating from a 40-ha controlled subsurface irrigation drainage technology coupled in series with a denitrification bioreactor. The intent of the denitrification bioreactor is to create an environment for anoxic microbial populations to support denitrification. We monitored the tile-drainage effluent and denitrification bioreactor water chemistry under a corn-soybean rotation to estimate the nutrient concentrations and the competence of the denitrification bioreactor to foster denitrification. Nitrate-N bearing tile drainage effluents ranged from less than 1.5 to 109 mg NO3- -N/L, with the nitrate concentration differences attributed primarily to the: 1) timing of nitrogen fertilization for corn, 2) soil mineralization and residue decomposition, and 3) intense rainfall events. The denitrification bioreactor was highly effective in reducing drainage water nitrate-N concentrations providing the rate of water flow through the denitrification bioreactor permitted sufficient time for equilibrium to be attained for the nitrate reduction reactions. The nitrate-N concentrations entering the denitrification bioreactor ranged from 0.4 to 103 mg NO3-?-N/L in 2018, whereas the outlet nitrate concentrations typically ranged from 0.3 to 5.2 mg NO3- -N/L in 2018. Nitrate tile-drainage effluent concentrations in 2019 were marginal, given soybeans obtain nitrogen from biological nitrogen fixation. Nutrient uptake by corn reduced the soil nitrate leaching pool and created nitrogen-bearing biomass, features important for formulating best management practices.
文摘There can be little argument that embryo quality is one of the most critical factors in the success of assisted reproductive techniques. Yet the current methods of grading embryos are subjective at best. While a number of different groups have described more qualitative means of assessing embryo quality, the current standard remains morphology. Morphology has proven a good standard, but it does not allow for the detection of chromosomal abnormalities nor can it assess the biochemical status of the embryo prior to transfer. This laboratory recently described a method to estimate embryo weight and suggested weight might be a good indicator of biochemical status. The objective of the present study was to determine the relationship between maternal body composition and embryo weight and determine the influence maternal chemistry had on embryo development. The data continue to suggest that maternal body composition, especially body fat, influences the chemical nature of the embryo and may play a critical role in long-term survival.
