to study the effects of nitrogen on tomato plant growth and the possibility of reducing nitrogen in drainage water, two nutrient solutions (complete nutrient solution (n+) and nutrient solution with a 30% decrease in n concentration (n-)) along with and three culture media (perlite, a mixture of perlite and nh4- enriched zeolite and finally a mixture of perlite and raw zeolite) were employed fo...

Few studies have quantified the effects of different levels and forms of nitrogen (N) deposition on soil nitrous oxide (N2O) emissions from temperate forest soils. A 5-year field experiment was conducted to investigate the effects of multiple forms and levels of N additions on soil N2O emissions, by using the static closed chamber method at Xi Mountain Experimental Forest Station in northern Ch...

Incubation experiment was conducted on four soil types in Nigeria using cattle dung (CD) at the rate of 2.5g/kg soil ( 5 t ha), Urea fertilizer at the rate of 0.1g/kg soil ( 200 kg ha ) and cattle dung (2.5g/kg soil) combined with Urea 0.05g/kg soil (100 kg ha) as treatments. The objective of the experiment was to compare the rate of OC, NH4 – N, NO3 – N and available P release on soils selecte...

A novel reactor design, coined a high density bioreactor (HDBR), is presented for the cultivation and study of high density microbial communities. Past studies have evaluated the performance of the reactor for the removal of COD(1) and nitrogen species(2-4) by heterotrophic and chemoautotrophic bacteria, respectively. The HDBR design eliminates the requirement for external flocculation/sediment...

The obligately ammonia-oxidizing bacterium Nitrosomonas europaea was incubated in medium containing 50 mM ammonium. Changes in the concentration of nitrite, the pH, and the NH4 and NH2OH-dependent O2 uptake activities of the cell suspension were monitored. The NH4 -dependent O2 uptake activity doubled over the first 3 h of incubation and then slowly returned to its original level over the follo...

OsNRT1.1a is a low-affinity nitrate (NO3 (-) ) transporter gene. In this study, another mRNA splicing product, OsNRT1.1b, putatively encoding a protein with six transmembrane domains, was identified based on the rice genomic database and bioinformatics analysis. OsNRT1.1a/OsNRT1.1b expression in Xenopus oocytes showed OsNRT1.1a-expressing oocytes accumulated (15) N levels to about half as compa...

Both nitrate (NO3-N) and ammonia (NH4-N) concentrations are in general highly variable during a lake’s seasonal cycle. During the growing seasonal peak, such concentrations can be very low due mainly to its’ sequestration by phytoplankton. With the aim to study NO3-N and NH4-N mean concentration variation along the increase of the trophic state of lakes, this study simultaneously analyses the i...

A freshwater "mussel mortality threshold" was explored as a function of porewater ammonium (NH4+) concentration, mussel biomass, and total nitrogen (N) utilizing a numerical model calibrated with data from mesocosms with and without mussels. A mortality threshold of 2 mg-N L-1 porewater NH4+ was selected based on a study that estimated 100% mortality of juvenile Lampsilis mussels exposed to 1.9...

The effects of different concentrations of CdCl2 and AlCl3 on NH4+ and NO2? oxidation in an aqueous system were investigated. AlCl3 had no effect on NH4+ removal and its oxidation to NO2?, whereas NO2? disappearance was greatly enhanced by AlCl3. In contrast, CdCl2 delayed removal of NH4+ and its subsequent oxidation to NO2? and also decreased the rate of NO2? disappearance. When compared to th...

Relatively little is known about the fixed NH4-N status of soils in the semi-arid tropics (SAT) but information is needed in view of its role in N cycling and the N economy of the soils. The distribution of fixed NI-L-N and C/N ratios of soil profiles from two benchmark Vertisols and one Alfisol in the Indian SAT were studied. From 15.9 to 58.6% of the total soil N was present as fixed NHa-N in...