Significant Differences In NO3 Research Articles

Biochar stimulates NH4+ turnover while decreasing NO3− production and N2O emissions in soils under long-term vegetable cultivation

A 15N-tracer incubation experiment was conducted to investigate the short-term effects of biochar on gross N transformation rates and nitrous oxide (N2O) emissions in soils under 1-year and 10-year vegetable cultivations. Biochar was applied at three rates: 0 (control), 10, and 30 t ha−1. Gross N transformation rates in the two vegetable soils varied in response to biochar application. Specifically, organic N oxidation into NO3− (ONorg) was almost negligible in the biochar-amended soils, and biochar application at 10 t ha−1 did not change either the rate of mineralization of organic N into NH4+ (MNorg) nor the inorganic N supply capacity (INS, ONorg + MNorg) in both soils, when compared to the control. However, 30 t ha−1 biochar decreased INS significantly, by inhibiting MNorg, in the 1-year vegetable soil but increased INS, by stimulating MNorg, in the 10-year vegetable soil. The rates of NH4+ oxidation into NO3− (ONH4), NO3− immobilization into organic N, and dissimilatory NO3− reduction into NH4+ were not influenced significantly by biochar application in the 1-year vegetable soil, resulting in no significant differences in NO3− production potential. Conversely, biochar decreased NO3− production potential significantly in the 10-year vegetable soil, by inhibiting ONH4 and increasing NH4+ immobilization into organic N (INH4), with more obvious effects under higher biochar application rates. Overall, the results demonstrate the capacity of biochar to stimulate NH4+ turnover and to decrease NO3− production potential in soil under long-term vegetable cultivation; however, the effect is limited under short-term vegetable cultivation. In addition, N2O emissions decreased significantly in biochar-amended vegetable soils.

Detection of nitrate and nitrite in different seafood

High-performance ion-exchange chromatography with suppressed conductivity (HPIEC-SCD) was validated for the determination of nitrite (NO2−) and nitrate (NO3−) in the edible part of diverse seafood species. Samples analyzed by HPIEC-SCD that were devoid of nitrite and nitrate were subjected to HRMS using a Q-exactive Orbitrap platform. As NO2− is not detectable in Q-Exactive Orbitrap, it was necessary to perform the oxidation of NO2− to NO3−. Accordingly, suitability of NO2− oxidation by H2O2 as a part of sample preparation for HPIEC-HRMS was elaborated. The difference in the concentration of NO3− before and after H2O2 treatment was used for the evaluation of eventual NO2− presence. The edible part of 53 fish, shrimp and bivalve species presented significant differences in NO3− levels especially between farmed (median = 44 μg/g) and wild species (median = 16 μg/g). The highest concentration of NO3− was found in smoked salmon samples (median = 60 μg/g) while NO2− was not revealed in any of the samples studied.

Effect of treated farm dairy effluent on E. coli, phosphorus and nitrogen leaching and greenhouse gas emissions: a field lysimeter study

Land application of farm dairy effluent (FDE) to pasture soils is the preferred practice in New Zealand. Recently, a new FDE treatment technology has been developed to recycle the water for washing the yard Cameron and Di (J Soils Sediments 2018). Here we report a lysimeter study to compare the leaching losses of Escherichia coli, phosphorus (P), and nitrogen (N) and emissions of greenhouse gases from the treated FDE compared with the untreated original FDE. Lysimeters were collected from a Balmoral silt loam soil (Typic Dystrudept, USDA) and installed in a field trench facility. Treatments included (1) treated effluent (TE), (2) a mixture of TE and recycled water (M), (3) untreated original FDE (FDE), and (4) water as control. The effluents were applied at a surface application rate of 24 mm on each lysimeter in May and again in September 2017. Measurements included leaching losses of E. coli, total phosphorus (TP), dissolved reactive phosphorus (DRP), total mineral nitrogen (TN), ammonium-N (NH4+-N), and nitrate-N (NO3−-N); emissions of nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4); herbage yield; and N uptake. The results showed that E. coli, TP, and DRP leaching losses from the TE were 1.31 × 1010 cfu/ha, 0.26 kg P/ha, and 0.009 kg DRP/ha and from M treatments were 6.96 × 108 cfu/ha, 0.18 kg P/ha, and 0.004 kg DRP/ha, respectively, which were significantly (P < 0.05) lower than those from the FDE which were 4.21 × 1010 cfu/ha, 1.75 kg P/ha, and 0.034 kg DRP/ha, respectively. There were no significant differences in NO3−-N leaching losses amongst the different forms of effluents. There were no significant differences in total N2O, CO2 emissions, and CH4 uptakes from the different effluents (P < 0.05). Herbage dry matter yields and N uptakes were also similar in the different effluent-treated lysimeters. Results from this research indicate that land application of the treated effluents (TE) or a mixture of TE plus clarified water (M) would result in significant environmental benefits by reducing E. coli and P leaching without increasing greenhouse gas emissions.

Temporal Dynamics of Nitrous Oxide Emission and Nitrate Leaching in Renovated Grassland with Repeated Application of Manure and/or Chemical Fertilizer

Managed grassland is occasionally renovated to maintain plant productivity by killing old vegetation, ploughing, and reseeding. This study aimed to investigate the combined effect of grassland renovation and long-term manure application on the temporal dynamics of nitrous oxide (N2O) emission and nitrate nitrogen (NO3−–N) leaching. The study was conducted from September 2013 to September 2016 in a managed grassland renovated in September 2013. In this grassland, two treatments were managed—chemical fertilizer application (F treatment) and the combined application of chemical fertilizer and beef cattle manure (MF treatment)—for eight years before the renovation. The control treatment without fertilization (CT) was newly established in the F treatment. The soil N2O flux was measured using a closed chamber method. A leachate sample was collected using a tension-free lysimeter that was installed at the bottom of the Ap horizon (25 cm deep), and total NO3−–N leaching was calculated from leachate NO3−–N concentration and drainage volume was estimated by the water balance method. In the first year after renovation, the absence of plant nitrogen uptake triggered NO3−–N leaching following rainfall during renovation and increased drainage water after thawing. NO3−–N movement from topsoil to deeper soil enhanced N2O production and emission from the soil. N2O emission in MF treatment was 1.6–2.0 times larger than those of CT and F treatments, and NO3−–N leaching in MF treatment was 2.3–2.6 times larger than those of CT and F treatments in the first year. Mineral nitrogen release derived from long-term manure application increased NO3−–N leaching and N2O emission. In the second year, N2O emission and NO3−–N leaching significantly decreased from the first year because of increased plant N uptake and decreased mineral nitrogen surplus, and no significant differences in N2O emission and NO3−–N leaching were observed among the treatments. In the second and third years, NO3−–N leaching was regulated by plant nitrogen uptake. There were no significant differences in NO3−–N leaching among the treatments, but N2O emission in MF treatment was significantly smaller than in the F treatment. Long-term manure application could be a possible option to mitigate N2O emission in permanent grassland; however, the risk of increased NO3−–N leaching and N2O emission in the renovation year induced by manure nitrogen release should be noted.

Residual analysis of nitric oxide fumigation on fresh fruit and vegetables

Nitric oxide (NO) is a newly discovered fumigant which is effective against a wide range of postharvest pests. To register NO with US EPA for commercial use as a pesticide and to ensure its safety to consumers, it is necessary to analyze residues of NO fumigated products. In this study, we analyzed nitrate (NO3−) and nitrite (NO2−) ion concentrations in liquid extracts as residues on 20 fresh products at 24h after 16h fumigation treatments and compared them from untreated controls to determine effects of nitric oxide fumigation. Each product was subjected to two identical NO fumigation treatments except one treatment was terminated by flushing with N2 and the other terminated by flushing with air. For most products, there were no significant differences in NO3− or NO2− level between the treatment that was terminated with nitrogen flush and the control. Only when NO fumigation treatment was terminated by flushing with normal air, there were significantly higher NO3− and NO2− concentrations in all fumigated products than both control and N2 flushed fumigated products. NO2− concentration was generally not detectable in both fumigated and control products. Therefore, our results indicated that there were no significant levels of residues from NO fumigated fresh products at 24h after fumigation when fumigation was terminated properly with nitrogen flushing.

Effect of Half and Whole Root Drying on Photosynthesis, Nitrate Concentration, and Nitrate Reductase Activity in Roots and Leaves of Micropropagated Apple Plants

Half or whole root systems of micropropagated `Gala' apple (Malus ×domestica Borkh.) plants were subjected to drought stress by regulating the osmotic potential of the nutrient solution using polyethylene glycol (20% w/v) to investigate the effect of root drying on NO3- content and metabolism in roots and leaves and on leaf photosynthesis. No significant difference in predawn leaf water potential was found between half root stress (HRS) and control (CK), while predawn leaf water potential from both was significantly higher than for the whole root stress (WRS) treatment. However, diurnal leaf water potential of HRS was lower than CK and higher than WRS during most of the daytime. Neither HRS nor WRS influenced foliar NO3- concentration, but both significantly reduced NO3- concentration in drought-stressed roots as early as 4 hours after stress treatment started. This reduced NO3- concentration was maintained in HRS and WRS roots to the end of the experiment. However, there were no significant differences in NO3- concerntation between CK roots and unstressed roots of HRS. Similar to the effect on root NO3- concentration, both HRS and WRS reduced nitrate reductase activity in drought-stressed roots. Moreover, leaf net photosynthesis, stomatal conductance and transpiration rate of HRS plants were reduced significantly throughout the experiment when compared with CK plants, but the values were higher than those of WRS plants in the first 7 days of stress treatment though not at later times. Net photosynthesis, stomatal conductance and transpiration rate were correlated to root NO3- concentration. This correlation may simply reflect the fact that water stress affected both NO3- concentration in roots and leaf gas exchange in the same direction.

Effect of Strip Tillage on Corn Nitrogen Uptake and Residual Soil Nitrate Accumulation Compared with No‐Tillage and Chisel Plow

Tillage and N management systems can have a significant effect on N use by corn (Zea mays L.) and nitrate (NO3–N) movement through the soil profile. Potential water quality and NO3–N loss problems associated with conventional tillage and fall‐applied N have prompted this study. The objective is to evaluate strip tillage effect on corn N uptake and NO3–N movement through the soil profile compared with chisel plow and no‐tillage systems. The three tillage systems implemented in this study were strip tillage, no‐tillage, and chisel plow along with two N application timings (fall and spring) of 170 kg N ha−1 for corn in a corn–soybean [Glycine max (L.) Merr.] rotation on two Iowa fields in 2001 and 2002. The three tillage systems were implemented every year for both crops (corn and soybean). Crop response, N uptake, and other soil NO3–N measurements were conducted on a randomized complete block design experiment. Grain yields and grain N uptake showed no significant improvement under strip tillage compared with no‐tillage or chisel plow systems. Tillage and N treatments caused no significant differences in NO3–N accumulation at the lower depths of the root zone (1.2 m). Strip tillage and no‐tillage resulted in lower residual soil NO3–N buildup than chisel plow in the 0‐ to 1.2‐m soil profile after 2 yr of tillage implementation. Tillage and N treatments did not cause significant differences in NO3–N concentration in water leachate collected at the 1.2‐m depth.

Fresh Parboiled Rice Hulls Serve as an Alternative to Perlite in Greenhouse Crop Substrates

Ten substrates were formulated by blending perlite or parboiled fresh rice hulls (PFH) at 20%, 30%, 40%, 50%, or 60% (v/v) with sphagnum peat. After 6 weeks, NH4+ concentrations were not significantly different among substrates containing perlite and those containing equivalent amounts of PFH. Nitrate concentrations were significantly higher in the 40% perlite substrate than in the 40% PFH substrate, but there were no significant differences in NO3- concentrations among the remaining substrates containing equivalent amounts of PFH or perlite. When tomato (Lycopersicon esculentum Mill.) was grown in the substrates for 5 weeks, tissue N concentrations were not significantly different between equivalent perlite and PFH-containing substrates. Non-parboiled fresh rice hulls produced organically contained a higher number of viable weed seeds than non-parboiled fresh rice hulls produced conventionally. No weed seeds germinated in the PFH. `Better Boy' tomato, `Bonanza Yellow' marigold (Tagetes patula L. French M.), `Orbit Cardinal' geranium (Pelargonium ×hortorum L.H. Bailey), `Cooler Blush' vinca (Catharanthus roseus L.G. Don), `Dazzler Rose Star' impatiens (Impatiens walleriana Hook. f.), and `Bingo Azure' pansy (Viola ×wittrockiana Gams) were grown in sphagnum peat-based substrates containing perlite or PFH at 10%, 15%, 20%, 25%, 30%, 35%, or 40% (v/v). Dry root weights of vinca and geranium were not significantly different among plants grown in the substrates. Tomato plants grown in 10%, 15%, 25%, 30%, and 35% PFH had significantly higher dry root weights than those grown in equivalent perlite-containing substrates. Impatiens grown in 35% PFH had higher dry root weights than those grown in 35% perlite. Marigold grown in 20% perlite had higher dry root weights than those grown in 20% PFH. However, there were no significant differences in impatiens or marigold dry root weights among the remaining substrates containing equivalent amounts of PFH or perlite. Dry root weights of pansy grown in 10%, 20% 25%, 35%, and 40% perlite were not significantly different from those grown in equivalent PFH-containing substrates. Across substrates, root dry weights of impatiens, marigold, and pansy grown in perlite-containing substrates were not significantly different from those grown in PFH-containing substrates. No significant difference in dry shoot weights of vinca, geranium, impatiens, and marigold occurred between equivalent perlite and PFH-containing substrates. Tomato plants grown in 20% to 40% perlite had significantly higher dry shoot weights than those grown in equivalent PFH-containing substrates. However, dry shoot weights of tomato grown in 10% to 15% perlite were not significantly different from those grown in equivalent PFH-containing substrates. Dry shoot weights of pansy grown in 10%, 25%, 30%, 35%, and 40% perlite were not significantly different from those grown in equivalent PFH substrates.

Limnological and morphometrical data of eight karstic systems `cenotes' of the Yucatan Peninsula, Mexico, during the dry season (February–May, 2001)

The karstic nature of the Yucatan Peninsula allows the formation of natural sink-holes from the dissolution of calcareous rock. These systems are almost the only epigean source of fresh water available in this region. In spite of their biological importance, little is known about the morphometric and limnologic characteristics of these karstic systems. We measured limnological variables in eight cenotes in central Quintana Roo during February–May, 2001. Zooplankton biomass and chlorophyll a were also measured in order to determine if the behavior of primary and secondary production was related to environmental parameters. Important short-term changes were observed in nutrients (NO3−, NO2−, PO43-), biomass, and chlorophyll a. The morphometrically conditioned productivity (MCP), which evaluates the cumulative effect of several morphometric variables on production (area, maximum length, shoreline development, perimeter), showed a negative correlation with respect to zooplankton biomass, as did also both pH and temperature. Conversely, NO3− and NO2− had a positive correlation with zooplankton biomass. No correlation was found for chlorophyll a. Significant differences in NO3− (F = 61.52, p<0.001), NO2− (F = 7.36, p<0.001), zooplankton biomass (F = 17.57, p<0.001), chlorophyll a (F = 62.19, p<0.001), and conductivity (F = 497.49, p<0.001) were found among the systems. These results indicate the existence of sharp differences between these karstic systems (oligotrophic, with smaller area, deep and less productive) and non-karstic ones, (eutrophic, larger area, shallow and more productive) but are similar to previous data from other karstic systems of Mexico and other parts of the world. However, understanding of these fragile tropical systems is in the initial phase. It is necessary to increase the intensity of these studies in order to allow a full explanation of their limnological behavior.

Spring ephemeral herbs and nitrogen cycling in a northern hardwood forest: an experimental test of the vernal dam hypothesis

In the late 1970s R.N. Muller and F.H. Bormann posited their "vernal dam" hypothesis, stating that spring-ephemeral herbs in deciduous forests serve as a temporary sink for N when overstory trees are dormant, and then release this N later, in the summer, when the trees are active. This hypothesis has gained wide acceptance, yet two of its critical assumptions have never been experimentally tested: (1) that N taken up by spring ephemerals would otherwise be lost from the ecosystem, and (2) that N from senesced ephemeral tissues contributes to increased rates of summertime N mineralization. To test these assumptions, I quantified patterns of N cycling and loss from a set of paired plots, half of which served as controls and from half of which all spring-ephemeral plants were removed. There were no significant differences in NO3- leaching between plots with and without spring ephemeral vegetation. These results are consistent with the relatively low rates of N uptake by the dominant spring ephemeral, Allium tricoccum, and its apparent preference for NH4+, which is far less mobile in soil than NO3-. In addition, based on sequential sampling, I found that soil microorganisms took up 8 times as much N during the spring than did spring-ephemeral herbs (microbial uptake=3.19 vs. plant uptake=0.41 g N m-2), suggesting that microbial immobilization of N is the dominant sink for N during this season. Removal of spring ephemeral vegetation also had no effect on summertime rates of net N mineralization. Furthermore, the addition of spring ephemeral litter to soil+forest floor microcosms did not significantly increase rates of N mineralization in a laboratory incubation. Instead, this experiment demonstrated the overwhelming influence of forest floor litter in controlling the release of mineral N from these soils. Overall, neither assumption of the vernal dam hypothesis holds true in this ecosystem, where patterns of N cycling and loss appear to be dominated by microbial decomposition of forest floor material and soil organic matter.

Allelopathic potential of Verbesina encelioides root leachate in soil

Verbesina encelioides (Cav.) Benth. &amp; Hook. F. ex. A. Gray (Asteraceae) is a perennial weed that interferes with the growth and establishment of crop species in semiarid regions of India. The present research was designed to understand the probable involvement of allelopathy in its interference mechanism. We studied the effect of soils amended with different dilutions of V. encelioides root leachate (full strength and 1:2 and 1:4 (v/v) ratios of root leachate to water) on the growth of radish seedlings (Raphanus sativus L.). Soils that were not amended were used as controls. We also investigated the influence of different levels of N fertilization (1, 5, and 10 mM) on the modification of the allelopathic potential of amended soils, in terms of their effect on soil total phenolics and radish seedling growth. The addition of both full strength and 1:2 dilution of V. encelioides root leachate resulted in significant (P &lt; 0.05) suppression of root (-25.7 and -17.2%, respectively) and shoot (-21.3 and -13.8%, respectively) growth of radish seedlings. The total level of phenolics in soil amended with full-strength (8.53 ± 0.55 µg/g), 1:2 dilution (5.43 ± 0.4 µg/g), and 1:4 dilution (4.17 ± 0.36 µg/g) was significantly (P &lt; 0.05) higher compared with that of control (2.98 ± 0.47 µg/g) soil. Although the different amounts of N fertilization in soil amended with V. encelioides root leachate could not counteract the probable allelopathic interference, we observed an increase in root growth of radish seedlings in soil amended with 10 mM N fertilization plus either a 1:2 dilution (+21.2%) or a 1:4 dilution (+36.5%) of root leachate. No significant differences in NO3- and NH4+ concentration were observed between control soil and soil amended with different amounts of root leachate and N fertlization. Since allelopathic activities include both inhibitory and stimulatory growth responses, the radish seedling growth responses to V. encelioides root leachate can be explained by allelopathy. High performance liquid chromatography data indicate qualitative and quantitative differences in phenolic peaks of both control and amended soil. Our research demonstrates the allelopathic potential of V. encelioides roots and the probable involvement of allelopathy in its interference success.