No abstract available

[en] With the objective of estimating the fertilizer use efficiency and A value, an experiment was performed under greenhouse conditions, using a Red Yellow Podzol (Serie Sertaozinho, Piracicaba-SP) and millet Setaria italica, L.) as a test plant. Ammonium sulfate was used at the rates of 0, 52, 104 and 208 mg of N per pot (2.5 kg of air dried soil). Two levels of sub(15)N enrichment were used: 2.281 Atoms % (enriched) and 0.045 Atoms % (depleted), with three replicates per treatment. Nitrogen use efficiency varied significantly with the fertilizer rates applied; values estimated with depleted fertilizer were always lower than those estimated with the enriched one. A value did not vary significantly with fertilizer rates. A values estimated with the enriched tracer were higher than those estimated with the depleted tracer for the lower and higher fertilizer rates. The values were equivalent for the intermediary rate. (author)

No abstract available

No abstract available

[en] Isotopic fractionation during ammonia volatilization from applied nitrogen fertilizers on calcareous soils is reported. After 24 hours of incubation, the value of the fractionation factor associated with this chemical process, is 1.027. That induced ¹⁵N enrichment of soil nitrogen and some change in natural isotopic abundances of soils concerned. The implications of these variations for the study of living plants are discussed

[en] A model of the global cycle of nitrogen and its isotopes is described. It takes into account geochemical reservoirs (nitrogen in magmatic metamorphic, and sedimentary rocks and in the atmosphere) and the nitrogen exchange between magmatic rocks and the outer mantle, the transition of nitrogen exchange between sedimentary rocks and the atmosphere. With the aid of the mathematical formalisms of the compartment theory and on the basis of all available delta¹¹N values assumptions regarding the isotope effects in forming these nitrogen fluxes data have been obtained on the degree of the nitrogen exchange between the earth crust and the outer mantle and on other nitrogen fluxes characterizing the global nitrogen cycle. (author)

[en] An experiment was carried out under laboratory conditions to determine the mineralization rate of Azola caroliniana in a soil classified as Low humic gley with two different contents of organic matter (a rice cropped soil and uncropped soil). Labelled ¹⁵N-azola was added to the soil at the rate of 38 t/ha of fresh matter, and soil samples were taken at 0 - 5 -10 - 15 - 20 - 25 and 30 days after addition to determine the mineral N content, total N and the activity of heterotrophic bacteria. N-azola was mineralized soon after its addition to soil, and the nitrate form was predominant in the cultivated soil where the recovery was 56.1% while ammonium was detected mainly in the uncropped soil where 43.5% was recovered in the first sampling (5 days incubation). Four weeks after azola incorporation, approximately 26% of total N-azola were available in both cropped and uncropped soils. The total recovery of N-azola applied was higher for the uncropped soil (82%) than the cropped soil (76%). Losses of N-azola were 18% and 24% in uncropped and cropped soils, respectively. Azola addition increased the rate of mineralization of nitrogen from natural organic matter indicating the occurrence of priming effects. The activity of the heterotrophic bacteria increased in the presence of azola, however, it was affected by temperature. The higher activity found in the uncropped soil suggests that the continuous flux of ammonium/nitrate from azola throughout the incubation period was due to an overall higher biological activity in the uncropped soil than in the cultivated soil. (author)

[en] Field and vegetational experiments have been carried out in the turf-podsolic soil in 1974-1977. Efficiency of open-hearth slag from Izhevsk metallurgical plant depends on the level of nitrogen nutrition. The greatest addition from the slag is received at the elevated level of nitrogen nutrition. The maximum total addition for 3 years resulting from the use of slag in the field experiment constituted 54.5 double centner forage units which is higher than the addition resulting from lime by 52.7 %. Besides, the slag produced positive effect upon the balance of the labelled ¹⁵N nitrogen in fertilizer: coefficient of the use of nitrogen in fertilizer during 2 years in the average increased by 7.1 and 11.2 % according to the nitrogen background of 230 and 460 mg/vessel

[en] The Soil and Water Management & Crop Nutrition (SWMCN) Subprogramme had a busy start of the year as we are preparing to join the global community to celebrate the International Year of Pulses 2016 (IYP2016). In this year, we will emphasize the work of the Subprogramme on using nitrogen-15 stable isotope for quantifying biological nitrogen fixation in Member States and the roles of pulses in improving soil fertility and in reducing greenhouse gases (GHGs) emission from agricultural production systems. As part of the event of IYP2016, a training course will be held this summer in Seibersdorf on the use of nitrogen-15 techniques for improving nitrogen management in agro-ecosystems. This course will focus in particular on how to assess, with isotopes, the capacity of grain legume crops (pulses) to capture nitrogen from the atmosphere. In addition, a joint event will be organized between SWMCN Subprogramme and the Plant Breeding and Genetic Section on ‘Enhancing Pulses for Food Security by Nuclear Applications’ before the annual General Conference in September 2016. This event will feature the roles of pulses for food security, poverty reduction and how nuclear applications can contribute towards pulse productivity.

No abstract available