Heterotrophic bacteria were studied which produced nitrite in the presence of ammonia and in the absence of nitrate. A soil extract medium was prepared which allowed good growth as well as nitrite production in the absence of nitrate. Quantitative data are recorded showing that ammonia decreases as nitrite accumulates when four different cultures are grown in the soil medium. Resting cell studi...

Nitrate sorption potentials of three surface soils (soils-1-3) were evaluated under different solute concentrations, i.e. 1-100 mg L(-1). Batch and diffusion-cell adsorption experiments were conducted to delineate the diffusion property and maximum specific nitrate adsorption capacity (MSNAC) of the soils. Ho's pseudo-second order model well fitted the batch adsorption kinetics data (R(2)>0.99)...

In 1989, a watershed acidification experiment was begun on the Fernow Experimental Forest in West Virginia, USA. Ammonium sulfate fertilizer (35.5 kg N ha yrand 40.5 kg S ha yr) was applied to a forested watershed (WS3) that supported a 20-year-old stand of eastern deciduous hardwoods. Additions of N and S are approximately twice the ambient deposition of nitrogen and sulfur in the adjacent mat...

Precipitation variability and magnitude are expected to change in many parts of the world over the 21st century. We examined the potential effects of intra-annual rainfall patterns on soil nitrogen (N) transport and transformation in the unsaturated soil zone using a deterministic dynamic modeling approach. The model based on TOUGHREACT [corrected], which has been tested and applied in several ...

irrigation management, soil tillage method and fertilizer management play important roles in increasing crop yield and water and solute movement in the soil profile. the present research was conducted to study the effects of a no-tillage system and nitrogen fertilizer on the mineral nitrogen movement and soil moisture under optimum irrigation conditions. the study was conducted at safiabad agri...

residues is applied to the land, it undergoes numerous chemical, physical and biological reactions. In its nitrate form (NO3), it can move down through soil into groundwater. Nitrate can also be a factor in surface water quality problems. In sufficient concentrations, nitrate in drinking water can be toxic to infants. Scientists are also investigating possible links between nitrate and other lo...

Nitrogen is an essential soil nutrient for plants, and lack of nitrogen commonly limits plant growth. Soil nitrogen is typically available to plants in two inorganic forms: nitrate and ammonium. To better understand how nitrate and ammonium differentially affect plant metabolism and development, we performed transcriptional profiling of the shoots of ammonium-supplied and nitrate-supplied Arabi...

, The nitrogen of the three above sources of nitrogen is not available to the plant until it has been converted to ammonia, the nitrites or nitrates. In sugarcane probably the most important of the above three compounds is the nitrate nitrogen form. When added to the soil in a commercial fertilizer, nitrate nitrogen, if applied in fairly large quantities, under certain conditions can also be th...

Landfill leachates, which are potential pollutants, may also carry significant amounts of nutrients that can be recycled by plants. We assessed the nutritional status and yield of wheat ( L.) and properties of a Rhodic Kandiudult soil (depths of 0-10, 10-20, 20-40, and 40-60 cm) after 11 applications of landfill leachate over 4 yr. In the last application, wheat received 0, 32.7, 65.4, 98.1, or...

The effects of elevated CO2 (750 ppm vs. 390 ppm) were evaluated on nitrogen (N) acquisition and assimilation by three Medicago truncatula genotypes, including two N-fixing-deficient mutants (dnf1-1 and dnf1-2) and their wild-type (Jemalong). The proportion of N acquisition from atmosphere and soil were quantified by (15)N stable isotope, and N transportation and assimilation-related genes and ...