The gingival crevicular fluid proteome in each clinical condition was different and its analysis may assist us in understanding periodontal pathogenesis.

The double exponential model that separates mineralizable soil organic N into active (Na) and slow (Ns) pools has been widely used to describe net N mineralization dynamics. However, the biological meanings of the model parameters and their relationships to soil properties and environmental conditions remain to be elucidated. In the present study, 18 soils were incubated at 35°C and 55% water‐holding capacity (WHC) for 41 wk and two soils at 16 factorial combinations of temperature (5, 15, 25, or 35°C) and moisture (8, 11, 15, or 19%) for 29 wk. Although the model closely fitted the net N mineralization data, the model parameters often appeared to lack biological meanings and could vary with incubation time, temperature, and soil moisture in unpredictable manners. Thus, the conventional double exponential model was modified by (i) using defined mineralization rate constants for Na and Ns under standard temperature (35°C) and moisture (approximately 55% WHC); and (ii) using soil‐specific and fixed Na and Ns values to estimate temperature‐ and moisture‐dependent rate constants under non‐standard conditions. This technique basically eliminated the time effect on the estimates of pool sizes and resulted in the rate constants with a consistent Q10 response to temperature and linear response to moisture changes. Predictions of soil net N mineralization dynamics under field conditions using the parameters estimated in laboratory agreed closely with the measured data. Multiple regression analysis indicated that the size of Na is correlated with the initial water‐soluble organic N and microbial biomass in soil, whereas Ns represents the combined effects of all the factors regulating long‐term net N mineralization.

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Abstract. The effect of a nitrification inhibitor on nitrous oxide (N 2 O) emissions across seasons, the effect of a urease inhibitor and a fine particle spray (both targeting ammonia (NH 3 ) loss) on N 2 O emissions, and the potential for productivity benefits and efficiencies by using these enhanced efficiency fertilisers (EEFs) were investigated in temperate pastures. The study compared three treatments over an eight month period (April to December 2010): (1) urea (U), (2) urea with a nitrification inhibitor (3,4-dimethylpyrazole phosphate) (DMPP), and (3) urea with a urease inhibitor (N-(n-butyl) thiophosphoric triamide (NBTPT)) (GU). In autumn, when NH 3 loss was predicted to be high, the effect of urea applied as a fine particle spray (containing urea, NBTPT and gibberellic acid (10 g ha -1 )) (FPA) on N 2 O emissions and productivity was determined.N 2 O emissions from urea applied to pastures were low, and were larger in spring than autumn due to soil moisture and temperature. DMPP was an effective tool for mitigating N 2 O emissions, decreasing fertiliser-induced N 2 O emissions relative to urea by 76% over eight months. However, the urease inhibitor (NBTPT) (GU) increased N 2 O emissions from urea by 153% over eight months. FPA had no impact on N 2 O, but was only examined during periods of low emission (autumn). No significant biomass productivity, agronomic efficiency benefits, or improvements in apparent fertiliser recovery were observed with the DMPP and GU treatments. A significant biomass productivity benefit was observed with the FPA treatment 55 days after fertiliser was applied, most likely because of the gibberellic acid. The outcomes highlight that although DMPP effectively decreased N 2 O emissions it had no impact on biomass productivity compared with urea. The use of the GU increased N 2 O emissions by preserving NH 3 in the soil. To avoid this a lower rate of N should be applied with the urease inhibitor.

Process-based models capture our understanding of key processes that interact to determine productivity and environmental outcomes. Combining measurements and modelling together help assess the consequences of these interactions, identify knowledge gaps and improve understanding of these processes. Here, we present a dataset (collected in a two-month fallow period) and list potential issues related to use of the APSIM model in predicting fluxes of soil water, heat, nitrogen (N) and carbon (C). Within the APSIM framework, two soil water modules (SoilWat and SWIM3) were used to predict soil evaporation and soil moisture content. SWIM3 tended to overestimate soil evaporation immediately after rainfall events, and SoilWat provided better predictions of evaporation. Our results highlight the need for testing the modules using data that includes wetting and drying cycles. Two soil temperature modules were also evaluated. Predictions of soil temperature were better for SoilTemp than the default module. APSIM configured with different combinations of soil water and temperature modules predicted nitrate dynamics well, but poorly predicted ammonium-N dynamics. The predicted ammonium-N pool empties several weeks after fertilisation, which was not observed, indicating that the processes of mineralisation and nitrification in APSIM require improvements. The fluxes of soil respiration and nitrous oxide, measured by chamber and micrometeorological methods, were roughly captured by APSIM. Discrepancies between the fluxes measured with chamber and micrometeorological techniques highlight difficulties in obtaining accurate measurements for evaluating performance of APSIM to predict gaseous fluxes. There was uncertainty associated with soil depth, which contributed to surface emissions. Our results showed that APSIM performance in simulating N2O fluxes should be considered in relation to data precision and uncertainty, especially the soil depths included in simulations. Finally, there was a major disconnection between the predicted N loss from denitrification (N2 + N2O) and that measured using the 15N balance technique.

Excess vigour is a problem in cool climate vineyards in Australia due to high soil Nfertility. High and low vigour blocks in three cool climate vineyards in Victoria, Australia, was surveyed. The relationship between soil N-fertility and grapevine vigour was tested. Vine vigour was reflected in measured internode length and leaf petiole N content. The average daily Nmineralization rate from soil organic matter (SOM) varied among the sites. Laboratory incubations revealed a positive relationship between soil total N content and average daily mineralizable-N in most sites. However, there are other factors involved in promoting excess vigour those to be taken into account.

Much of the fertiliser nitrogen (N) used in agriculture is lost to the atmosphere as nitric oxide and nitrogen dioxide (collectively referred to as NOx), ammonia (NH3), and nitrous oxide (N2O). The lost N is not only an economic problem for the farmer; it also contaminates the environment and affects human health. Because the values obtained for NOx and NH3 loss to the atmosphere from agriculture in Monsoon Asia have been questioned, we quantitatively determined, using new techniques, the emission of these gases from a maize crop fertilised with urea in northern China. The fertiliser was deep-placed by traditional farmers’ practice and emissions of NOx and NH3were determined with a chemiluminescence analyser and a backward Lagrangian stochastic dispersion technique. The emission measurements indicate that 1.2% of the applied N was lost as NOx. This loss is far greater than measured or derived by other researchers, and we suggest that this is because our measurements were made continuously rather than as spot measurements with static chambers. The results for NH3 show that, although the fertiliser was placed below the soil surface, a small amount (7% of the applied N) was still lost to the atmosphere. Soil analyses indicate that the rate of nitrification in this soil was low, and the maximum nitrate (NO3–) concentration found in the soil (31.4 µg N/g) was only 3.9% of the fertiliser N added. Thus, there is little potential for NO3– to be leached down the profile. A study using soil cores and acetylene inhibition to measure denitrifying activity suggested that the rate of denitrification in this soil was also very low. The results suggest that in this soil with slow nitrification and denitrification rates and little potential for leaching, deep placement of the urea to limit NH3 volatilisation is an effective method for increasing fertiliser use efficiency.