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The objective of this study was to derive a better understanding of the manner in which N serves the nutritional needs of corn (Zea mays L.) and thereby afford a basis for improved fertilization practices. Measurements of uptake, translocation and utilization of tagged nitrogen (N) fertilizer in irrigated corn as influenced by time and rate of N application were made in a field experiment at the University of Nebraska Field Laboratory. Plant parts of root, crown, foliage, and eventually ear and grain were taken and analyzed for total N, NO3‐‐N and isotope ratio at eight growth stages.Application of N at planting resulted in greater vegetative production, but summer sidedressed N effected slightly larger grain production with a higher grain/stover ratio. Isotope ratio analyses revealed significantly greater utilization of fertilizer N in grain production with delayed application due to more active root uptake and translocation of the fertilizer source during the grain filling period.Following harvest, residual mineral N in soil from applied fertilizer was greater with summer sidedressing such that 24% more of the N applied could be accounted for in the crop and soil than with planting time application.

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The objective of this study was to assess the effects of different dietary strategies in post-weaned piglets on gas emissions and animal performance. Eighty piglets were allotted in ten environmentally-controlled chambers. Piglets were fed with five different isoenergetic diets: control, low protein (LP), inclusion of sugar beet pulp (SBP), addition of benzoic acid (BA) and a combination of LP, SBP and BA (LP + SBP + BA). The gases analyzed were ammonia (NH 3 ), methane (CH 4 ), nitrous oxide (N 2 O) and carbon dioxide (CO 2 ). For NH 3 , the most effective treatment was LP, with a reduction of 61%. The LP + SBP + BA reduced NH 3 emission by 51%, the inclusion of SBP by 43% and the least effective technique was BA, which decreased by 9.5%, compared to control. The CH 4 emission was reduced by 30% for LP, but was increased by 23% for SBP and 24.6% for LP + SBP + BA. Benzoic acid did not differ from control group. The N 2 O emission did not show statistically differences, and CO 2 and carbon dioxide equivalent (CO 2eq ) emission increased with LP + SBP + BA (14 and 15% respectively), but were not affected by other diets. No effect of dietary treatment was observed on the growth performances compared with control group (p > 0.05). We can conclude that the best technique to reduce NH 3 emission was LP. Inclusion of SBP decreases NH 3 emission, but can increase greenhouse gas emissions. It would be interesting to evaluate the effect of higher percentages of BA because the promising results. Combining techniques is not a good strategy to obtain an additive effect in gas emissions reduction.

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