Total Amount Of Nitrate Research Articles

Validation of a sensor-system for real-time measurement of mineralized nitrogen in soils

When reducing the negative impact of agriculture on the environment, one major approach is to substantially decrease the nitrate contamination of the groundwater originating from mineral and organic fertilization. However, efficient plant production relies on sufficient nutrient supply. Finding the balance between appropriate plant nutrition and ground water conservation is a challenge. Appropriate nitrogen fertilization relies on the measurement of mineralized nitrogen (Nmin) - the total amount of nitrate and ammonium - in the soil. Taking soil samples with an auger and subsequent chemical analyses in a laboratory is state of the art. However, this process is time-consuming and often time-delayed. The Stenon FarmLab, a sensor spade, is a new device which claims to measure soil Nmin and other soil parameters in real-time with spectral methods. The aim of this study was to validate the Nmin measurements of the Stenon FarmLab with the common laboratory method. The authors conducted a series of 20 measurements consisting of a varying number of individual values per measurement. In total, 211 individual values on 15 different field sites in three regions in Bavaria, Germany were analyzed. Reference samples for laboratory analysis were taken simultaneously with a sampling auger. Only 181 of the 211 individual values were considered in the evaluation as Nmin contents of less than 42 kg N ha−1 and greater than 189 kg N ha−1 exceeded FarmLab's measurement range. The results showed that the Stenon FarmLab overestimated Nmin in 75 % of the cases in comparison to the laboratory analysis. On average, the mean values of the sampled sites differed by 38 kg N ha−1 showing a 69 % mean deviation from the laboratory. The overall coefficient of determination (R2) was 0.3 for individual measurements and 0.66 for the mean values of a site. In conclusion, the Stenon FarmLab is a good approach for a more time-saving method regarding relative differences within or between fields. However, absolute values measured with the Stenon FarmLab, which are required for demand-driven fertilization, are not accurate enough: the system needs to be further improved to match reference methods.

A deep placement of lime nitrogen reduces the nitrate leaching and promotes soybean growth and seed yield

Deep placement of coated urea, lime nitrogen (Lime N), or urea with a nitrification inhibitor, 3,4-dimethylpyrazole phosphate (DMPP-U) did not inhibit N fixation activity, and it promoted soybean growth and seed yield. However, the effect of deep placement on the N budget including N leaching has not been evaluated. In this research, soybean plants were cultivated with a basal deep placement of urea, Lime N, or DMPP-U, and the control without deep placement of N fertilizer in lysimeters filled with Andosols. The nitrate was the principal N leachate and most of them leached until the flowering stage. The total amount of leached nitrate was the highest in urea deep placement, and it was reduced by the deep placement of Lime N or DMPP-U. In 2020, the total amount of nitrate in the leachate during the cultivation was 0.95, 1.83, and 2.78 ​g ​N m−2 in control, Lime N, and urea, respectively. The seed yield was higher in Lime N (424 ​g ​m−2) and urea (399 ​g ​m−2) than in the control (267 ​g ​m−2). The total amount of N accumulated in the shoots was higher in Lime N (32.1 ​g ​N m−2) than in the control (26.5 ​g ​N m−2) and urea (24.2 ​g ​N m−2) treatments. These results indicated that soybean plants with Lime N might assimilate more N both from N fertilizer and N2 fixation compared with control plants. Soil incubation test confirmed that the Lime N or DMPP-U retarded nitrification than urea.

Effect of timing of cattle urine deposition and pasture composition on nitrogen leaching losses

AbstractA lysimeter experiment using undisturbed monoliths from a stony silt loam soil was carried out to quantify the effects different pasture types on N losses from urine applied to soil on different dates. Three pasture types were tested: (a) perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) (PRG/WC), (b) perennial ryegrass/white clover/plantain (Plantago lanceolata) (PRG/WC/P) and (c) Italian ryegrass (Lolium multiforum)/white clover/plantain (IRG/WC/P), with four different urine applications dates (late summer, early autumn, mid‐autumn and late autumn). Cattle urine was applied at the equivalent of 700 kg N−1 ha−1. There was a significant reduction in total amount of nitrate (NO3−‐N) leached under the PRG/WC/P (14% reduction) and IRG/WC/P (24% reduction) compared with the PRG/WC. High NO3−‐N leaching losses were found at each urine application date (>181 kg NO3−‐N/ha), suggesting there may be higher than expected N leaching losses when urine is deposited onto shallow stony soils, during warmer months (late summer and early autumn). There was no significant interaction between pasture type and urine timing on NO3−‐N leaching losses.

Effect of Washing and Cooking on Nitrate Content of Potatoes (cv. Diamant) and Implications for Mitigating Human Health Risk in Iran

The nitrite and nitrate in foodstuff and their associated harmful effects are of great concern for human health. More than 80% of human nitrate intake is attributed to the consumption of vegetables and fruits, and for this reason, more attention should be paid to the consumption of such foodstuffs and reduction of nitrate intake. Therefore, this study aimed to determine the variation of nitrate and nitrite content in potato during home preparation, process, and cooking methods, and assessed their health risk in different age groups for the first time in Iran. The nitrite content in all of the samples was lower than the apparatus detection limit so results are reported for nitrate. A total of 471 tubers of potato cultivar Diamant were assessed. The nitrate content was measured based on the tuber weight and also in different parts of potato. The impact of different washing and baking methods on nitrate contents were also assessed. Ion chromatography was employed to determine the nitrate content. The US Environmental Protection Agency (EPA) method covering the determination of nitrate in food was used to assess the health risk associated with potato consumption. The results showed that the average nitrate content was 123.26 mg/kg which was lower than the safe limit of nitrate. The results also showed that the total amount of nitrate in potato peel was 35% higher than in its central parts. Different washing methods could reduce the nitrate amount by 7.79 to 14.73%. Boiling potato could significantly reduce the amount of nitrate by 59.7%, while frying increased it by 52%. There were significant differences among different potato cooking methods in terms of changes in the nitrate content (P ˂ 0.001). This means that exposure in all age groups was less than the standard limits and potato intake was considered safe to all age groups. As there were significant changes in the nitrate content, it was concluded that washing and cooking methods, except frying, were suitable methods to reduce nitrate intake.

Effects of Precipitation on Nonpoint Sources of Nitrogen Contamination to Surface Waters in the U.S. Great Plains

Declining surface water quality is of great concern across the Great Plains. Recent trends in the earth’s climate can create abrupt changes in precipitation, which can alter the impact of nonpoint sources on water quality. A 2-year study [dry (2009) and wet (2010) year] was initiated to assess the impact of nitrate nitrogen (N) loss from the Roca watershed on water quality in Salt Creek. The water flow and nitrate N concentration was determined weekly in Salt Creek. The predicted average nitrate N concentration in runoff during the dry year (38.3 mg L−1) was almost five times greater than that (7.9 mg L−1) for the wet year. However, the predicted amount of nitrate N in runoff was similar for both years because the runoff for the wet year (51.8 million m3) was about five times greater than that for the dry year (10.7 million m3). The total amount of nitrate N found in Salt Creek was 18 and 127 metric tons for the dry and wet years, respectively. These data implied that 95% (dry year) and 69% (wet year) of the nitrate N has been removed from streams water in Salt Creek. Factors responsible for removing nitrate N from water include heavy growth of algae, weeds, and aquatic plants as well as denitrification and volatilization reactions. The predicted amount of nitrate N lost from soils by leaching was almost seven times greater for the wet (1,037 metric tons) than the dry year (156 metric tons). It was concluded that high precipitation for the wet year raised both the amount of nitrate N in runoff and loading into Salt Creek and could increase the negative impact on water quality.

Assessing nitrate leaching in cropping systems based on integrated weed management using the STICS soil–crop model

Abstract Agriculture in Europe and other parts of the world is currently under strong pressure to reduce its reliance on pesticides. Regarding arable crops, strategies based on integrated weed management (IWM) combine several agronomic practices aimed at reducing herbicide use, but these strategies can generate negative collateral effects, such as increased nitrate leaching. An evaluation of nitrate leaching in a long-term experiment set up in 2000 was performed for five tested cropping systems: four IWM-based systems and one reference system. After the validation of the predictive performance of the STICS soil–crop model, nitrate leaching was simulated for the five cropping systems tested over the 12 years of the experiment and over 12 years of implementing alternative scenarios (i.e. the introduction of early sowing for winter cereals, ceasing deep tillage and the introduction of a mustard catch crop). The results showed that the total amount of nitrate leaching varied between cropping systems and was lowest in the cropping system using no herbicide and that with no tillage, two systems combining several agronomic practices. Alternative scenarios based on both early sowing of winter crops and the introduction of catch crops can reduce the total amount of nitrate leached by 25 to 43% over the 12 years of simulations, although early sowing can, in some cases, increase nitrate leaching. This study contributes to the multi-criteria evaluation of innovative cropping systems.

Active secretion and protective effect of salivary nitrate against stress in human volunteers and rats

Up to 25% of the circulating nitrate in blood is actively taken up, concentrated, and secreted into saliva by the salivary glands. Salivary nitrate can be reduced to nitrite by the commensal bacteria in the oral cavity or stomach and then further converted to nitric oxide (NO) in vivo, which may play a role in gastric protection. However, whether salivary nitrate is actively secreted in human beings has not yet been determined. This study was designed to determine whether salivary nitrate is actively secreted in human beings as an acute stress response and what role salivary nitrate plays in stress-induced gastric injury. To observe salivary nitrate function under stress conditions, alteration of salivary nitrate and nitrite was analyzed among 22 healthy volunteers before and after a strong stress activity, jumping down from a platform at the height of 68m. A series of stress indexes was analyzed to monitor the stress situation. We found that both the concentration and the total amount of nitrate in mixed saliva were significantly increased in the human volunteers immediately after the jump, with an additional increase 1h later (p<0.01). Saliva nitrite reached a maximum immediately after the jump and was maintained 1h later. To study the biological functions of salivary nitrate and nitrite in stress protection, we further carried out a water-immersion-restraint stress (WIRS) assay in male adult rats with bilateral parotid and submandibular duct ligature (BPSDL). Intragastric nitrate, nitrite, and NO; gastric mucosal blood flow; and gastric ulcer index (UI) were monitored and nitrate was administrated in drinking water to compensate for nitrate secretion in BPSDL animals. Significantly decreased levels of intragastric nitrate, nitrite, and NO and gastric mucosal blood flow were measured in BPSDL rats during the WIRS assay compared to sham control rats (p<0.05). Recovery was observed in the BPSDL rats upon nitrate administration. The WIRS-induced UI was significantly higher in the BPSDL animals compared to controls, and nitrate administration rescued the WIRS-induced gastric injury in BPSDL rats. In conclusion, this study suggests that stress promotes salivary nitrate secretion and nitrite formation, which may play important roles in gastric protection against stress-induced injury via the nitrate-dependent NO pathway.

Quantifying nitrate dynamics in an oligotrophic lake using Δ&amp;lt;suP&amp;gt;17&amp;lt;/sup&amp;gt;O

Abstract. The stable isotopic compositions of nitrate, including the 17O anomalies (Δ17O), were determined twice in 1 yr (June and August 2007) in the oligotrophic water column of Lake Mashu, Japan. These data were then used to quantify the geochemical dynamics of nitrate in the lake, by using the deposition rate of the atmospheric nitrate onto the entire catchment area of the lake. The total amount of nitrate in the lake water decreased from 4.2 to 2.1 Mmol during the period between the observations, while the average Δ17O values remained uniform at +2.5‰. The Δ17O values corresponded to an small and uniform mixing ratio of atmospheric nitrate to total nitrate of 9.7 ± 0.8%. These results indicate that 0.52 ± 0.34 Mmol of the remineralized nitrate was fed into the water column through nitrification, while 2.6 ± 0.4 Mmol of nitrate was simultaneously removed from the water column by assimilation, during the period between the observations. The lake water dissolved nitrate was characterized by rapid removal through assimilation during summer until it was almost completely removed from the euphotic layer, as well as continuous feeding into the lake through nitrification (3.2 ± 0.3 Mmol a−1) and deposition (0.35 ± 0.2 Mmol a−1), regardless of the seasons. The 15N-depleted nitrogen isotopic compositions of nitrate were as low as −6.5‰ in June, which also indicates that in-lake nitrification is the major source of nitrate in the lake and suggests that there is low potential for denitrification in and around the lake. Atmospheric nitrate deposited into the lake will be assimilated quickly, having a mean residence time of 1.2 ± 0.1 yr. In addition, more than 90% of the assimilated nitrate will be remineralized to nitrate and re-assimilated via active nitrogen cycling in the lake.

Simulation of field data by a basic three-dimensional model of interactive root growth

Published field data for lupins grown in a deep sandy soil in the wheatbelt of south-western Australia were used to test the predictive ability of a model of three-dimensional root growth. The model has the capacity to simulate the growth of individual root sections in response to the supply and demand for water and nitrate. N mineralisation was not modelled explicitly, but was accounted for through the use of a seasonally variable mineralisation input derived from the field data. Simulated nitrogen and water contents and root length densities in the soil profile agreed well with observed profiles, although all were slightly under-predicted. A sensitivity analysis revealed that model predictions were most sensitive to the drained upper limit values (v/v) and the mineralisation rates (μgN m−3 s−1) incorporated as external inputs to the model, along with the unit rate of N2 fixation (mol nodule−1 s−1) and unit root growth rates (μm mol−1 s−1) which are physiological parameters previously calibrated for lupins. The amount of nitrate leached was predicted well. Spatial plots of nitrate leaching were a close inverse of the root length density plots, with the highest nitrate leaching below the inter-plant zones, and the least nitrate leaching directly below each plant. These results suggest that the root distribution of a legume species such as lupin can have an effect on the leaching of nitrate to depth. It may thus be possible to reduce the total amount of nitrate leached under lupin crops by investigating factors such as the spatial deployment of roots, planting densities and intercropping.

Millipedes and Earthworms Increase the Decomposition Rate of 15N-Labelled Winter Rape Litter in an Arable Field

Effects of millipedes and earthworms on the decomposition of 15N-labelled litter of winter oilseed rape were investigated in a microcosm field experiment over a period of 264 days on an oat field near Göttingen managed by integrated farming. A total of 32 microcosms were filled with defaunated soil. 15N-labelled rape litter was placed either on top of the soil or buried into the soil simulating mulching and ploughing, respectively. To the microcosms nine adult individuals of Blaniulus guttulatus (Diplopoda) and two of Aporrectodea caliginosa (Lumbricidae) were added separately or in combination. In general, the presence of the animals accelerated the decomposition rate of the litter material. The effects were most pronounced in the presence of Aporrectodea caliginosa. The total amount of nitrate, ammonium and the amount of 15N leached from the microcosms was increased in the presence of earthworms or of both earthworms and millipedes. Both species proved to be important members of the detritus food web of the agricultural system studied.

Soil fertility in a long‐term fertilizer trial with different tillage systems

The presented results originate from a field experiment established in 1972 on an Eutric cambisol with two main factors: soil tillage (conventional‐, reduced‐, and no‐tillage) and NPK fertilization. The test plants were maize and winter wheat in two years rotation. The long‐term soil fertility without and with optimum fertilization, the influence of fertilization, tillage and crop sequence on grain yields, the organic carbon content (Corg) and the nitrate infiltration are discussed. In the course of years without any NPK fertilization grain yields of maize and winter wheat decreased significantly and reached a minimum level which was modified however by the actual climatic conditions. The analogous yield level of optimum NPK fertilization at maize showed a growing tendence while at wheat it remained mostly constant. The method of soil tillage influenced grain yield of winter wheat to a lesser extent than the yield of maize. Grain yields of maize and winter wheat were consistently lower with no‐till as compared to reduced or conventional tillage, however the differences with w. wheat were much smaller. The effect of tillage was especially high at N0 P0 K0. Crop rotation had a positive effect on the yields of maize. For winter wheat at N0 P0 K0 oneself was the better forecrop, while at optimum N and PK maize performed a little better. Corgcontent of soil slightly increased in the course of 25 years not only on the fertilized plots but on the nil plots too. Increasing N‐doses showed only a little effect on the Corg. There was a little positive effect of no‐till on Corg content of soil as well as compared fall ploughing. Soil tillage did not much influence the total amount of nitrate in the soil profile. The distribution of nitrate‐N in the soil profile was more affected by the actual climatical circumstances than by the system of tillage. However big nitrate accumulations were found in the subsoil according to different soil tillage systems at some other times, as well as lack of it, which suppose the possibility of a relative quick nitrate infiltration.

The balance of supply of nutrients and demands of biological production and denitrification in a temperate latitude shelf sea — a treatment of the southern North Sea as an extended estuary

Abstract Data from the NERC North Sea Programme (1988–1989) and the OMEX project (1993–1997), and subsequent numerical modelling based on that data, enables budgets to be drawn up which allow the scales of a number of processes which are significant in shelf seas to be quantified. In winter the N:P ratio is lower in many areas of the southern North Sea than in any of the source waters. The deficit in the load of nitrate-N relative to that which would be present assuming conservative mixing of river and ocean waters is 580 ktonnes. This is probably due to denitrification. Considering the flushing rate it is equivalent to a maximum rate of loss of 0.7 mmol N m−2 day−1. A loss of this magnitude confirms the suggestion of Seitzinger and Giblin (Seitzinger, S.P., Giblin, A.E., 1996. Biogeochemistry 35, 235–260.) that the relatively high productivity in shelf seas such as the North Sea fuels significant levels of denitrification. The wide area of the shelf involved makes these areas net sinks for nitrogen in global budgets. A net flow of ocean water onto the shelf equivalent to 0.6 Sv (1 Sv=106 m3 s−1) containing nitrate at the winter concentration of 7.5 μM is required to maintain the nitrogen balance in the North Sea. An analysis of the sources of dissolved inorganic nitrogen (DIN) (and silicon) contributing to the change in dissolved nitrogen load between November 1988 and January 1989 (526 ktonnes N, 242 ktonnes Si) shows that between November and January the principal source of dissolved nitrate over the southern North Sea is probably from recycling of detrital or dissolved organic nitrogen (DON) already present in the system (383 ktonnes N) and not from direct inputs of new nitrogen. In one region, the German Bight, inputs of new nitrogen from rivers and the atmosphere approach 50% of the observed change. The ratio of annual primary production in different areas of the North Sea to the estimate of available nitrogen varies between five off the Dutch and German coasts and two off the UK coast. This indicates that the high productivity of the North Sea is maintained by both the total amount of nitrate that is supplied to the system and recycling in its shallow waters. Both the ratio and the efficiency of recycling are lower off the UK coast where light limitation of production is more likely.

Effect of soil type on nitrate uptake by wheat shoots characterized using 15N-labelled NH4 NO3-fertilizer and in vitro, leaf nitrate reductase activity

Wheat plants grown in a greenhouse in containers filled with chalky (CP) or loamy (LP) soil were fertilized with NH415NO3 or 15NH4 NO3 (5 atom% 15N), initial soil nitrate levels being lower in chalky soil. Both the total amount of nitrate and the proportion derived from fertilizer were higher in leaves of plants grown on chalky soil, however, increased inorganic N was not paralleled by a higher organic N content in the CP leaves. In vitro NR activity of the youngest fully expanded leaves confirmed that NO3 flux into the shoot was higher for CP than for LP. The ratio of the ‘proportion of fertilizer in the flag leaf NO3 pool divided by the proportion of fertilizer in the soil total N pool’ reached a maximum (0.8) at the onset of the flag leaves for CP but decreased to 0.5 at the time of flowering because stored NO3 from fertilizer was predominantly re-used to feed other parts of the plants. In LP, NO3 was not remobilized and the ratio remained at 0.8. Higher in vitro NR activity in the CP flag leaf confirmed that release and re-use of stored nitrate occurred and that plants grown on chalky soils appear to have an enhanced ability to utilise nitrate.