No abstract

InN. lg'7g. Effect of nitrogen fertll\zer on nitrogen fractions and amino acid .composition of spring wheat. Can' J. Plant Grain from hard red spring wheat (Triticum aestivum'Neepawa') grown with nine rares of N fertilizer (0-400 tg/ha) was analyzed for total N, non-protein N (NPN) ' and amino acids. In addition, the amino acid compositions of the various soluble protein fractions were determined. The percent6ges of total N, NPN' and protein The long-term average protein content of Kolderup (1974) 1964\.Protein fractionation was carried out according to a modification of methods described by Chen and Bushuk (1970) and Paulis et al. (1969).Samples of meal (10 g) were extracted sequentially with the various aqueous solvents (Table l) by agitation on a rotary shaker (250 rpm) in a 250-ml polyethylene centrifuge bottle containing five glass marbles. At specified times, the aqueous extract was cleared by centrifugation at I 500 x g followed by passage through glass wool filters. The albumin and globulin were subsequently separated by dialysis (Chen and Bushuk 1970). The ethanol was removed from the gliadin fraction by dialysis at 2'C. The material from each fractionation step was lyophilized and its total N content determined by nesslerization after digestion (Williams I 964).Samples were hydrolyzed in 6 N HCI for 22 h at 108'C in evacuated hydrolysis tubes. Hydroly-

No abstract

In August 1982, the U.S. Geological Survey, in cooperation with the Fairbanks North Star Borough, undertook a study of the ground-water system in and near the Fairbanks Sanitary Landfill. Water quality and hydrologic data were collected at 22 observation wells and at 2 river sites. The water table beneath the landfill is less than 10 feet below land surface and fluctuates seasonally about 2 feet. The slope of the water table to the north indicates the general direction of groundwater flow from the Tanana River toward the Chena River. Several wells within the landfill show anomalously high concentrations (compared to background levels) of chloride, iron, and manganese, and relatively low values of pH and dissolved-oxygen concentrations. However, the values of these constituents and properties remain at background levels in wells north and west of the landfill.

Our knowledge of root mass decomposition processes has greatly benefited from studies carried out in natural and semi-natural ecosystems. It is less known, however, how root mass loss might occur in intensively managed ecosystems, such as agricultural grasslands, which receive chronic additions of nitrogen (N) fertilizers. Key questions remain about (1) how repeated N applications either in organic or inorganic forms might influence fine root mass decomposition, and (2) what implications root mass loss might have for soil carbon (C) storage. Here, we use a long-term grassland experiment established in 1970 at Hillsborough, Northern Ireland (UK), to address how repeated additions of organic (i.e., liquid manures) and inorganic (i.e., NPK) fertilizers over >45 yr might influence fine root mass decomposition and how. We found that after a 10-month incubation period under field conditions, highest root mass loss (~43%) was associated with highest additions of organic slurries, whereas lowest root mass loss (~29%) occurred in inorganically N-fertilized and unfertilized soils. Root decomposition was significantly and negatively related to root C:N ratios and fungal-to-bacterial (F:B) ratios. Root decomposition, however, was not related to changes in soil C stocks or rates of soil C accumulation. N applications either maintained or increased (up to three times) soil C accumulation compared to unfertilized soils after five decades of intensive management. Our findings suggest that in the short-term organic fertilization can enhance root detritus decomposition (thus promoting N release in soils for plant uptake) while contributing in the long-term to soil C accumulation either through extra C inputs from manures or through N-induced effects on microbial activity or both. Further studies need to address how this dual effect of organic fertilization could contribute making grassland intensification more sustainable by reducing the use of artificial NPK fertilizers.