751-3404-00L  Nutrient Fluxes in Soil-Plant Systems: The Case of Nitrogen

SemesterSpring Semester 2019
LecturersA. Oberson Dräyer, T. I. McLaren, F. Tamburini
Periodicityyearly recurring course
Language of instructionEnglish
CommentNumber of participants limited to 18.

Prerequisites: Successful completion of "Plant Nutrition I (751-3401-00L)" and
" Pflanzenernährung II - Integriertes Nährstoffmanagement (751-3402-00L) is mandatory.

AbstractThe course teaches knowledge and experimental techniques to study pools and processes underlying nutrient fluxes in soil-plant systems. Methods will be learned i) to analyze elements dynamics, ii) to determine the use efficiency by crops of nutrients added with fertilizers, iii) to study the fate of fertilizer nutrients not taken up by the crop and iv) to estimate symbiotic N2 fixation by legumes.
ObjectiveUsing the element nitrogen (N) as model case, the student gets familiarized with techniques to assess the dynamics and availability of nutrients in the soil-plant system and to determine the use efficiency by crops of nutrients added with fertilizers. He/she learns about the use of stable isotope techniques for analyzing nutrient fluxes in soil-plant systems, and about the use of biochemical methods to obtain indicators on nutrient transformations. He/she is able to evaluate critically the tools used in agricultural or environmental studies dealing with fluxes of elements in soil-plant systems and the interpretation made of the results. Knowledge about processes and pools underlying nutrient cycles in agro-ecosystems will be improved.
The student learns to work in the laboratory within a small team, to organize work in sub-groups, to exchange results obtained by these sub-groups, to look for information outside of the course (e.g. in the library, in the internet), to read and analyze this information critically, to synthesize both, the information from the literature and from the groups, and to present it in a written report and in an oral presentation.
ContentThis course teaches knowledge and methods to analyze the dynamics of elements in soil-plant systems and to determine the use efficiency by crops of nutrients added with mineral and organic fertilizers. It provides knowledge about various techniques (isotopic, chemical, biochemical) that can be used to evaluate
i) content of elements in fertilizers, soils and plants;
ii) availability of elements in soils and fertilizers for plants;
iii) transfer of elements from a fertilizer to a crop;
iv) symbiotic N2 fixation by legumes.
Nitrogen will be used as model case.
The course will start with the discussion of analytical results on elemental contents in an organic fertilizer (e.g. animal manure, plant material) that has previously been labeled with the isotope 15N. To test the N efficiency of this fertilizer, a pot experiment (glasshouse study) will be designed. It will include soils with different characteristics, two test plants and fertilization treatments including the 15N labeled organic fertilizer and appropriate reference treatments.
Soils will be characterized for basic chemical properties and for biochemical characteristics that are related to the N dynamics. Plants will be harvested and analyzed for their dry matter production, their N isotope composition and for elemental contents. From the direct (15N) labeling approach, the proportion of N in the plant derived from the added fertilizers and the percentage of added fertilizer recovered in plant material will be calculated. The 15N analyses in the soil and in the plant material after the crop cycle will allow drawing a balance of the added fertilizer and discussing N losses. The comparison of 15N excess in legume and non-legume test plants will demonstrate the use of the enriched dilution method to estimate symbiotic N2 fixation by the legume.

The experiments are discussed and carried out by the students supervised by group members (two senior scientists, PhDs, laboratory staff). The students carry out the data analysis and report their findings in a written report and in an oral presentation.
Lecture notesDocumentations will be made available during the course.
LiteratureIndications during the course.