In PNAS, Sebilo et al. (1) present the fate of labeled nitrate in the soil–plant system over three decades and attempt to determine “to which extent and over which time periods fertilizer N stored in soil organic matter is rereleased for either uptake in crops or export into the hydrosphere.” I suspect that this mechanism of immobilization-mineralization turnover described by Sebilo et al. (1) ...

We studied the effects of adding water, nitrate and sucrose on denitrification in a riparian forest that receives nitrate in drainage from cornfields. We used large (3-6 m2) flow-through chambers to sample N 2 0 emissions from surface soils. N2 emissions were estimated by comparing N 2 0 efflux in chambers with or without acetylene addition. Water and solutions of nitrate or sucrose were sprink...

The aims of the study were to analyse the concentration of nitrate and ammonium ions in soil solutions obtained using MacroRhizon miniaturized composite suction cups under field conditions and to determine potential nitrogen leaching from soil fertilized with three types of fertilizers (standard urea, slow-release urea, and ammonium nitrate) at the doses of 90 and 180 kg ha-1, applied once or d...

After consumption of molecular oxygen, anaerobic microbial communities can use a continuum of alternative electron acceptors such as nitrate, manganese oxides, iron oxides, sulfate or CO2, with decreasing spans of available free energy. The electron transfer to insoluble metal oxides or to partner organisms such as methanogens may require the employment of electron carrier systems such as soil ...

Th ere is noticeable negative impact on soil and water quality caused by nutrient leaching, especially nitrate. Five regions in Croatia are preliminary delineated as nitrate vulnerable zones, including potentially vulnerable zones (PVZ) and vulnerable zones (VZ), one of them being Varaždin County. Agricultural land spreads on 59% of its total area. Th e survey was carried out to analyze two ava...

We assessed the effects of canopy position and feral pig disturbance on soil moisture, pH, and inorganic nitrogen concentrations beneath canopies of Quercus agrifolia and surrounding grasslands on Santa Cruz Island, California. Percent soil moisture, pH, nitrate-N, and total inorganic nitrogen varied significantly with canopy position. Soil moisture decreased, and pH increased along transects f...

Unpublished studies in the files of the Pineapple Research Institute of Hawaii indicate that under present cultural conditions the .pineapp1e plant displays superior performance with a foliar applied combination of ammonium and nitrate nitrogen than with either form of nitrogen alone. The studies presented here were undertaken to evaluate ammonium nitrate as a nitrogen source under different so...

The microbial processes of denitrification and dissimilatory nitrate reduction to ammonium (DNRA) are two important nitrate reducing mechanisms in soil, which are responsible for the loss of nitrate ([Formula: see text]) and production of the potent greenhouse gas, nitrous oxide (N(2)O). A number of factors are known to control these processes, including O(2) concentrations and moisture content...

Peatlands cover more than 30% of the Finnish land area and impact N2O fluxes. Denitrifiers release N2O as an intermediate or end product. In situ N2O emissions of a near pH neutral pristine fen soil in Finnish Lapland were marginal during gas chamber measurements. However, nitrate and ammonium fertilization significantly stimulated in situ N2O emissions. Stimulation with nitrate was stronger th...

Invasion by the African grass Andropogon gayanus is drastically altering the understory structure of oligotrophic savannas in tropical Australia. We compared nitrogen (N) relations and phenology of A. gayanus and native grasses to examine the impact of invasion on N cycling and to determine possible reasons for invasiveness of A. gayanus. Andropogon gayanus produced up to 10 and four times more...