Biochar (BC) application to agricultural soils could potentially sequester recalcitrant C, increase N retention, increase water holding capacity, and decrease greenhouse gas (GHG) emissions. Biochar addition to soils can alter soil N cycling and in some cases decrease extractable mineral N (NO and NH) and NO emissions. These benefits are not uniformly observed across varying soil types, N ferti...

We conducted continuous-flow experiments on intact sediment cores from Laguna Madre, Sabine Lake, East Matagorda Bay, and Nueces Estuary to evaluate internal nitrogen (N) sources, sinks, and retention mechanisms in Texas estuaries having different salinities. Mean ammonium (NH ) flux ranged from slight uptake (negative values) 4 to NH production rates of about 300 mmol m22 h21 (units used for a...

The Soil and Water Assessment Tool (SWAT) nitrogen (N) water quality model considers the artificial inputs associated with human activities, including point and nonpoint source pollution loads. Although SWAT has the ability to simulate atmospheric N deposition and fixation, they were not considered in the modeling research. N deposition from the air is an important and considerable pathway for ...

Predicting impacts of climate change or alternative management on both food production and environment safety in agroecosystems is drawing great attention in the scientific community. Most of the existing agroecosystem models emphasize either crop growth or soil processes. This paper reports the latest development of an agroecosystem model (Crop-DNDC) by integrating detailed crop growth algorit...

The need to understand the eeects of anthropogenic perturbations on the ocean carbon cycle has sparked a new interest in biogeochemical models in recent years. These models are now being coupled with physical ocean circulation models. For this coupling to generate realistic uxes of nutrients and carbon, the biogeochemical equations need to exhibit realistic dynamics. As a rst step in the develo...

Nitrogen-15 ( N)-labeled biogas slurry (digested anaerobic organic residues (DAOR)) and chemical 15 fertilizer (CF) were applied to soil with low fertility cropped with rice. The N dilution method was used to 15 estimate the N uptake and recovery; potted soil was labeled with 1.0 atom % excess [ N] ammonium chloride 15 NH Cl. Certain select soil characteristics were also measured in soil amende...

Surplus nitrogen (N) in ground and surface water is of concern in intensive agricultural regions. Surplus N leaches during lengthy periods where annual crop systems are used in temperate regions. This paper presents a model to estimate the surplus N available for leaching to ground water beneath agricultural systems and applies the model to watersheds in an intensive maize and soybean productio...

The C(3) grass Poa trivialis and the C(4) grass Panicum maximum were grown in sand culture and received a complete nutrient solution with nitrogen supplied as 1.5 mol m(-3) NH(4)NO(3). (15)N tracer techniques were used to quantify the relative use of root uptake and mobilization in supplying nitrogen to growing leaves in intact plants which either continued to receive nitrogen or which received...

Article history: Received: 09.06.2015. Received in revised form: 01.10.2015. Accepted: 08.10.2015. Liquid nitrogen is expected to be used as a jet medium in petroleum engineering because of its cryogenic and non-polluting characteristics. To identify the velocity distribution characteristics of liquid nitrogen jet, a computational fluid dynamics model was built by coupling the equations for nit...

Small patterned-ground features (PGFs) in the Arctic have unique soil properties that vary with latitude and may greatly affect tundra biogeochemistry. Because nitrogen availability can strongly limit arctic vegetation growth, we examined how soil nitrogen transformations differ between PGFs and the surrounding inter-PGF tundra along an arctic latitudinal gradient. We collected soils at eight s...