Soil mineral nitrogen benefits derived from legumes and comparisons of the apparent recovery of legume or fertiliser nitrogen by wheat

Nitrogen (N) contributed by legumes is an important component of N supply to subsequent cereal crops, yet few Australian grain-growers routinely monitor soil mineral N before applying N fertiliser. Soil and crop N data from 16 dryland experiments conducted in eastern Australia from 1989–2016 were examined to explore the possibility of developing simple predictive relationships to assist farmer decision-making. In each experiment, legume crops were harvested for grain or brown-manured (BM, terminated before maturity with herbicide), and wheat, barley or canola were grown. Soil mineral N measured immediately before sowing wheat in the following year was significantly higher (P < 0.05) after 31 of the 33 legume pre-cropping treatments than adjacent non-legume controls. The average improvements in soil mineral N were greater for legume BM (60 ± 16 kg N/ha; n = 5) than grain crops (35 ± 20 kg N/ha; n = 26), but soil N benefits were similar when expressed on the basis of summer fallow rainfall (0.15 ± 0.09 kg N/ha per mm), residual legume shoot dry matter (9 ± 5 kg N/ha per t/ha), or total legume residue N (28 ± 11%). Legume grain crops increased soil mineral N by 18 ± 9 kg N/ha per t/ha grain harvested. Apparent recovery of legume residue N by wheat averaged 30 ± 10% for 20 legume treatments in a subset of eight experiments. Apparent recovery of fertiliser N in the absence of legumes in two of these experiments was 64 ± 16% of the 51–75 kg fertiliser-N/ha supplied. The 25 year dataset provided new insights into the expected availability of soil mineral N after legumes and the relative value of legume N to a following wheat crop, which can guide farmer decisions regarding N fertiliser use.Mark B. Peoples, Antony D. Swan, Laura Goward, John A. Kirkegaard, James R. Hunt, Guangdi D. Li, Graeme D. Schwenke, David F. Herridge, Michael Moodie, Nigel Wilhelm, Trent Potter, Matthew D. Denton, Claire Browne, Lori A. Phillips, and Dil Fayaz Kha

Continued investigations into techniques producing selective chemical reactions on surfaces and target spheres and related studies. Final report

This report describes efforts leading to the development and characterization of a compact ion source and optical transfer system producing relatively high current density ion beams. The ion source and beam transfer system represent a major advance in the state of the art in that high current densities at low kinetic energies have been achieved for high molecular weight polyatomic ions. Indeed, the ion beams produced display ion abundance patterns typical of simple low energy electron impact ionization processes

Identification of [(GS)2AsSe)]- in rabbit bile by size-exclusion chromatography and simultaneous multielement-specific detection by inductively coupled plasma atomic emission spectroscopy.

An arsenic-selenium metabolite that exhibited the same arsenic and selenium X-ray absorption near-edge spectra as the synthetic seleno-bis(S-glutathionyl) arsinium ion [(GS)2AsSe]- was recently detected in rabbit bile within 25 min after intravenous injection of rabbits with sodium selenite and sodium arsenite. X-ray absorption spectroscopy did not (and cannot) conclusively identify the sulfur-donor in the in vivo sample. After similar treatment of rabbits, we analyzed the collected bile samples by size-exclusion chromatography (SEC) using inductively coupled plasma atomic emission spectroscopy (ICP-AES) to monitor arsenic, selenium and sulfur simultaneously. The bulk of arsenic and selenium eluted in a single peak, the intensity of which was greatly increased upon spiking of the bile samples with synthethic [(GS)2AsSe]-. Hence, we identify [(GS)2AsSe]- as the major metabolite in bile after exposure of rabbits to selenite and arsenite. The reported SEC-ICP-AES method is the first chromatographic procedure to identify this biochemically important metabolite in biological fluids and is thus a true alternative to X-ray absorption spectroscopy, which is not available to many chemists

Synthesis, X-ray absorption spectroscopy and purification of the seleno-bis (S-glutathionyl) arsenium anion from slenide, arsenite and glutathione.

We report a new synthesis of the seleno-bis (S-glutathionyl) arsinium anion, [(GS)(2)AsSe]. An aqueous solution of bis-glutathionylarsenous acid. (GS)(2)As-OH, prepared from stoichiometric glutathione and arsenite. was reacted in situ with a solution of sodium hydrogen selenide. prepared from elemental selenium and sodium borohydride. Analysis of the arsenic and selenium K-edge X-ray absorption spectra indicated virtually quantitative formation of [(GS)(2)AsSe](-), with As-Se and As-S distances of 2.31 and 2.25 Angstrom, respectively, and the concentrated sample allowed a definitive X-ray spectroscopic characterization. Size-exclusion chromatography was used to separate [(GS)(2)AsSe] from residual borate in the reaction mixture