1) Comment: General Comments: The manuscript presents an extensive analysis of 13C, NO3 and NH4 -uptake versus irradiance experiments for the Arctic subsurface chlorophyll maxima (SCM). NO3 and NH4 – uptake versus irradiance experiments are rarely conducted alongside traditional “P vs E” curves, so the paper includes some novel information on the rates of NO3 and NH4 uptake compared to carbon f...

Understanding the preference of a crop for forms nitrogen (N) is important to ensure efficient use N-sources in agriculture. A study was conducted assess nutrient uptake and dry matter yield six vegetable crops under different ratios ammonium- N (NH4+-N) nitrate-N (NO3–-N) growth medium. Seedlings cabbage, carrot, capsicum, knolkhol, lettuce, tomato, were supplied with five N-treatments (NH4+-N...

BACKGROUND AND AIMS It has recently found that lowland rice grown hydroponically is exceptionally efficient in absorbing NO3-, raising the possibility that rice and other wetland plants growing in flooded soil may absorb significant amounts of NO3- formed by nitrification of NH4+ in the rhizosphere. This is important because (a) this NO3- is otherwise lost through denitrification in the soil bu...

We conducted a series of stepwise NO3 2 additions to investigate the response of NO3 2 uptake to short-term (acute) changes in N concentration in 3 prairie streams. Observed NO3 2 uptake rates increased with short-term elevations in NO3 2 concentration and were consistent with linear and Michaelis–Menten kinetics models. We compiled these data with uptake rates from additional published studies...

Wheat is one of the most important food crops in the world, its availability affects global food security. In this study, we investigated variations in NH4(+) and NO3(-) fluxes in the fine roots of wheat using a scanning ion-selective electrode technique in the presence of different nitrogen (N) forms, N concentrations, and pH levels as well as under water stress. Our results show that the fine...