Higher Total Nitrogen Content Research Articles

TOTAL NITROGEN CONTENT IN SEDIMENTS IN THE MANGROVE AND CRAB CONSERVATION AREA OF TARAKAN CITY

Nitrogen in sediments is an essential element for plants that play a role in the process of photosynthesis and stimulate growth. This study aims to examine the total Nitrogen (N) content in sediments based on differences in depth in the Mangrove and Crab Conservation Area of Pamusian Village, Tarakan City. The method used in the research is quantitative descriptive method by describing the content of Nitrogen (N) in sediments based on differences in depth at each research station and determining the location of sampling points for sampling using purposive sampling method. Sediment sampling was carried out at 3 station points, namely the Pamusian River flow area, the watchtower area and the area near residential areas. Sediment sample testing was carried out at the Soil Laboratory of the Faculty of Agriculture, Borneo University of Tarakan. The results of this study showed that the Nitrogen (N) content in sediments in the Mangrove and Crab Conservation Area of Pamusian Village at a depth of 10 cm ranged from 0.25 - 0.32%, a depth of 20 cm ranged from 0.19 - 0.24%, and a depth of 30 cm ranged from 0.14 - 0.20%. The highest total nitrogen content is at a depth of 10 cm and the station that has the highest total nitrogen content is station 3.

A hyperthermophilic anaerobic fermentation platform for highly efficient short chain fatty acids production from thermal hydrolyzed sludge

In this study, a carboxylate platform of hyperthermophilic (70 ℃) anaerobic fermentation (HAF) for short chain fatty acids (SCFAs) production from thermal hydrolyzed sludge (THS) was established. The long-term performance for SCFAs production and the microbial communities of this HAF under different SRTs were systematically investigated. Under the optimum SRT of 3 d, the HAF had the highest acetate production rate of 1.12 g COD/L/d which accounted for 60% in SCFAs. It also rendered a good performance in SCFAs production, with concentration, production rate and yield of 6.61 g COD/L, 1.86 g COD/L/d and 324 g COD/kg VSSin, respectively. Nearly no biogas produced from this system, which reduced the loss of carbon sources from the system. This was due to the inhibition of methanogenesis by the hyperthermophilic condition and the high content of total ammonia nitrogen (TAN) and free ammonia nitrogen (FAN). Tepidimicrobium, Bhargavaea and XBB1006 were the dominant genus-level biomarkers under the optimum SRT, which facilitated the decomposition of monosaccharides, amino acids, terpenoids and polyketides into SCFAs. This work provides an applicable anaerobic carboxylate platform for highly efficient SCFAs production from excess sludge.

Effect of microbial communities on nitrogen and phosphorus metabolism in rivers with different heavy metal pollution.

Small urban and rural rivers usually face heavy metal pollution as a result of urbanization and industrial and agricultural activities. To elucidate the metabolic capacity of microbial communities on nitrogen and phosphorus cycle in river sediments under different heavy metal pollution backgrounds, this study collected samples in situ from two typical rivers, Tiquan River and Mianyuan River, with different heavy metal pollution levels. The microbial community structure and metabolic capacity of nitrogen and phosphorus cycles of sediment microorganisms were analyzed by high-throughput sequencing. The results showed that the major heavy metals in the sediments of the Tiquan River were Zn, Cu, Pb, and Cd with the contents of 103.80, 30.65, 25.95, and 0.44 mg/kg, respectively, while the major heavy metals in the sediments of the Mianyuan River were Cd and Cu with the contents of 0.60 and 27.81 mg/kg, respectively. The dominant bacteria Steroidobacter, Marmoricola, and Bacillus in the sediments of the Tiquan River had positive correlations with Cu, Zn, and Pb while are negatively correlated with Cd. Cd had a positive correlation with Rubrivivax, and Cu had a positive correlation with Gaiella in the sediments of the Mianyuan River. The dominant bacteria in the sediments of the Tiquan River showed strong phosphorus metabolic ability, and the dominant bacteria in the sediments of the Mianyuan River showed strong nitrogen metabolic ability, corresponding to the lower total phosphorus content in the Tiquan River and the higher total nitrogen content in the Mianyuan River. The results of this study showed that resistant bacteria became dominant bacteria due to the stress of heavy metals, and these bacteria showed strong nitrogen and phosphorus metabolic ability. It can provide theoretical support for the pollution prevention and control of small urban and rural rivers and have positive significance for maintaining the healthy development of rivers.

Ammoniacal and Nitrate Nitrogen Release Pattern from Biochar and Biochar Blended Urea Fertilizers in Sandy Soil

Biochar, an organic product of thermal decomposition of biomass in an oxygen limited environment can be used as a nutrient carrier to delay the release of nutrients into the soil, reduce nutrient leaching, and improve the nutrient utilization efficiency of fertilizers. Nutritional enhancement of biochar through fertilizer blending could be a low cost but high efficiency solution compared to non-blended fertilizers. However, the rate of nutrient release from the blended biochar fertilizer in different soils is ambiguous. Hence a 12 month incubation study was conducted in sandy soil (ultisol) of Thiruvananthapuram district of Kerala to elucidate the ammoniacal and nitrate nitrogen release rate and pattern from the produced paddy husk biochar, biochar and biochar bentonite (1:1) each blended with urea fertilizer in different ratios (1:0.5, 1:1, 1:2) including an absolute control. The individual effects of biochar, biochar-bentonite and urea were also studied. Paddy husk biochar was produced by the process of slow pyrolysis and biochar- blended urea fertilizers by the adsorbent process. To evaluate the influence of bentonite clay on the nutrient release pattern of biochar, it was blended with biochar and urea fertilizer. The highest total nitrogen content among the produced fertilizers was recorded in biochar: urea in 1:2 (33.04%) followed by biochar-bentonite: urea in a 1:2 ratio (31.13%). The incubation study revealed that the maximum release of ammoniacal nitrogen from soil+ urea fertilizer was at 30 days (115.73 mg kg-1) followed by a sharp decline, maintaining a low value till the end of incubation, whereas the release was sustained and gradually increased to reach a maximum at the 180th day (117.6 mg kg-1) for soil+ biochar: urea in 1:1 ratio. Nitrate nitrogen also followed the same trend with the maximum release observed for biochar: urea in 1:1 on the 150th day (151.2 mg kg-1). The release of nitrate nitrogen was more than that of ammoniacal nitrogen throughout the incubation period for all the treatments. Among the blended fertilizers, content of both ammoniacal and nitrate nitrogen were comparatively less for biochar –bentonite blended urea fertilizers. Thus, blending of urea with biochar/ biochar-bentonite prolonged the duration of maximum nutrient release.

Annual burying of straw after pelletizing: A novel and feasible way to improve soil fertility and productivity in Northeast China

Increasing the amount of straw returning has the potential to improve soil fertility, but is not widely accepted due to yield reductions in regions with low temperatures and precipitation. Thus, annual straw burying with large amounts after pelletizing was established considering soil fertility, crop yield and economic income. A three-year field trial with a large amount (75 Mg ha−1 year−1) of pelletized straw (PS75) and chopped straw (CS75), normal amount (15 Mg ha−1 year−1) of chopped straw (CS15), and no straw returning (CK) was conducted for spring maize. PS75 increased the soil total carbon content by 8–17 % and 29–51 % as compared to the other treatments between 0–20 and 20–40 cm respectively. PS75 also had a higher total nitrogen content, moderate soil C/N ratio, lower bulk density, and comparable soil pH in the third year. Specifically, PS75 increased grain yield by 5–7 % relative to CK, and 6–21 % relative to CS15 in the second and third years. PS75 also increased grain yield by 5–28 % than CS75 in the three years with higher kernel number and 100-kernel weight. This was partly attributed to a longer grain filling period due to higher soil carbon and nitrogen contents for PS75 than others. Notably, PS75 exhibited increased trends in grain yield and economic income with experimental year compared to CK. Overall, annual pelletized straw burying with a large amount is a feasible pathway for improving the soil fertility and crop yield in Northeast China.

Co-composting poultry carcasses with wood-based, distillers’ grain and cow manure biochar to increase core compost temperatures and reduce leachate's COD

Composting has been recognized as a viable method to dispose of animal carcasses. Common concerns related to the composting process include low core temperatures, leachate generation, and ammonia emissions. This study tested co-composting full-size poultry carcasses with commercially available biochars at an aeration rate of 0.8 L∙min−1. Biochars prepared by gasifying wood pallets, distillers’ grains, and cow manure were added to the composting bins at the 13% rate (by volume). Results showed that poultry carcasses with wood-based and cow manure biochar increased temperatures by 2.0 to 3.3 °C. All biochar-amended bins met the time–temperature criteria to eliminate avian influenza (H7N1) viruses, which could not be achieved without biochar addition. Wood-based biochar amendment lowered the cumulative chemical oxygen demand of the leachate samples by 87% (P = 0.02). At the rate studied, the biochar amendment did not significantly affect ammonia emissions (P = 0.56). BET surface area of wood-based biochar was 1.4 and 28 times greater than that of cow manure and distillers’ grain biochar, respectively. Compared to no biochar addition, wood-based biochar resulted in significantly higher compost temperatures (P = 0.02), lower leachate COD values (P = 0.02), and a higher total nitrogen content (P = 0.01) while it did not cause an increase in sodium content (P = 0.94) of the finished compost. In conclusion, amending the poultry carcass composting process with wood-based biochar (13% by volume) is recommended, especially to eliminate disease-causing agents.

The Soil Environment of Abandoned Charcoal Kiln Platforms in a Low-Altitude Central European Forest

This study examines the soil environment of eight charcoal kiln platforms and the neighboring soil in Czech and Bohemian low-altitude forest stands. Both mixed and undisturbed soil samples were used to assess the hydrophysical soil properties, nutrient content, cation exchange capacity, enzyme activity, and soil active carbon content, while soil color, stoniness, root density, and horizon thickness were estimated in the field. Charcoal-rich horizons had high total organic carbon concentrations and total nitrogen content (about 150% and 40% higher than in the organomineral horizons of the control plot, respectively), with total carbon stocks being higher than those in neighboring forest soils. Fine root density was highest in the charcoal-rich horizons, encouraged by high soil porosity, aeration, and favorable chemical properties. Enzyme group activity differed between individual soil horizons and kiln and control plots, with depolymerization enzyme activity highest in charcoal-rich horizons and humification enzyme activity highest in mineral horizons. Phosphatase, chitinase, and phenoloxidase activity were highest in charcoal-rich horizons, while β-glucosidase activity remained similar across horizons. After long-term abandonment, kiln sites shift from inhospitable sites to localized hotspots for plant and microbial growth, having more favorable physical, enzymatic, and chemical soil properties than the surrounding areas. This study confirmed that kiln production platforms act as microhabitat hotspots, also providing information on a wide spectrum of soil properties linked with soil microorganisms and root growth.

Plant types shape soil microbial composition, diversity, function, and co‐occurrence patterns in cultivated land of a karst area

AbstractPlants can alter microbial communities through root exudates, and change the characteristics of the soil. However, the relationship between soil microbial communities and environmental factors is not well understood. Here, we studied bacterial and fungal communities and their relationships with environmental factors. We integrated data of environmental factors, microbial composition, diversity, functional prediction, and co‐occurrence network from uncultivated, maize, cabbage, and cocozelle soils in a karst area of Southwest China. Soil bacterial and fungal community composition differed with plant types. Maize soil had more taxa and greater alpha diversity of bacteria and fungi than other soils. In maize soil, the relative abundance of Actinobacteria and Ascomycota was significantly lower than that in uncultivated soil, while its contents of soil organic matter (OM), alkali‐hydrolyzable nitrogen, and total nitrogen (TN) showed the opposite trend. These indicators were not significantly different between cabbage and cocozelle soils. The results of the Mantel test and the RDA analysis indicated that TN and OM were important drivers of bacterial and fungal communities. Functional prediction and network analysis showed that maize soil had a high nitrogen fixation capacity and a complex and stable network. To summarize, maize soil not had a low relative abundance of Ascomycota and high content of TN and OM, nitrogen fixation ability, and a rich microbial community. Therefore, cultivating maize is suitable for improving soil microbial community. These findings might help in formulating a reasonable cultivation management program to prevent land degradation in the karst areas.

Melon/cowpea intercropping pattern influenced the N and C soil cycling and the abundance of soil rare bacterial taxa.

The high use of pesticides, herbicides, and unsustainable farming practices resulted in losses of soil quality. Sustainable farming practices such as intercropping could be a good alternative to traditional monocrop, especially using legumes such as cowpea (Vigna unguiculata L. Walp). In this study, different melon and cowpea intercropping patterns (melon mixed with cowpea in the same row (MC1); alternating one melon row and one cowpea row (MC2); alternating two melon rows and one cowpea row (MC3)) were assayed to study the intercropping effect on soil bacterial community through 16S rRNA region in a 3-year experiment. The results indicated that intercropping showed high content of total organic carbon, total nitrogen and ammonium, melon yield, and bacterial diversity as well as higher levels of beneficial soil microorganisms such a Pseudomonas, Aeromicrobium, Niastella, or Sphingomonas which can promote plant growth and plant defense against pathogens. Furthermore, intercropping showed a higher rare taxa diversity in two (MC1 and MC2) out of the three intercropping systems. In addition, N-cycling genes such as nirB, nosZ, and amoA were more abundant in MC1 and MC2 whereas the narG predicted gene was far more abundant in the intercropping systems than in the monocrop at the end of the 3-year experiment. This research fills a gap in knowledge about the importance of soil bacteria in an intercropping melon/cowpea pattern, showing the benefits to yield and soil quality with a decrease in N fertilization.

Effects of the Different Loading Characters of Cattle Manure as Inoculum Towards the Composting Process of Coconut Pulp Waste

The current study evaluated the effects of loading characters of cattle manure as inocula on the composting of coconut pulp residue. A series of experiments were carried out to evaluate characteristics of compost generated from the different treatments. Results showed that total organic carbon of both finished compost T1 (56%) and T2 (57%) were close to that of the normal compost. The results of the study showed that that composts T2 had higher total nitrogen content (1.53%) than that of compost T1 which contained around 1.34%, and both are still in the normal range of total nitrogen of the finished composts. The electrical conductivity of compost T2 (625 mS/m) was about two times higher than that of compost T1 (296 mS/m) suggesting that the compost T1 was feasible used as a fertilizer in agriculture.

Characterization of lignocellulosic crop residues for potential biogas production in Zimbabwe

AbstractLignocellulosic biomass is considered to be an abundant and cheap resource for biogas plants. Efficient production of biogas from lignocelluloses depends upon its proximate composition. This short communication characterizes the proximate composition of locally available lignocellulosic crop residues (LCRs) – wheat straw, maize stover and soybean straw – as potential feedstocks for biogas production. Standard Methods for the Examination of Water and Wastewater were used to determine its physicochemical characteristics. Cellulose, lignocellulose and lignin content of the biomass were evaluated after Soxhlet ectraction. Results show that proximate composition varied widely amongst LCRs. Lignocellulosic crop residues were acidic in nature with high total nitrogen (TN) content, hence the need for some buffering in anaerobic digestion (AD). Soybean straw and wheat straw showed the highest pH and TN content, respectively. However, all LCRs contained more than 30% cellulose, suggesting their potential use in AD. Wheat straw reported the highest cellulose (37.8%) and hemicellulose (28.2%) content, and it was thus considered to be the most competitive feedstock for AD. Soybean straw had the lowest cellulose and hemicellulose content but it was found to have the highest lignin content (23.5%). The findings imply that soybean straw will have the lowest AD efficiency. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.

Atténuation de l'impact du déficit hydrique sur une culture de petit pois par la combinaison d'amendements organiques et de systèmes d'irrigation localisés

Cette recherche visait à évaluer l’impact de deux systèmes d'irrigation combinés à un amendement organique du sol, sur les paramètres hydrodynamiques et chimiques du sol et sur la productivité d'une culture de petit pois "Pisum sativum L. " soumise à des conditions de stress hydrique. Les résultats obtenus ont montré que les rampes poreuses permettent une meilleure stabilité du stock d'eau avec une amplitude de 30 mm contre 50,7 mm pour le système au goutte à goutte et un développement racinaire de petit pois plus intéressant avec une différence d'environ 2,5 cm par rapport au système de goutte à goutte. Le rendement n'a pas été significativement affecté et nous avons enregistré une différence de 3,43% en faveur des rampes poreuses. En revanche, la nodulation des racines et la fixation symbiotique de l'azote dépendaient du système d'irrigation, et nous avons trouvé une teneur en azote total plus élevée pour les sols irrigués par des rampes poreuses qui a atteint 1,4 g/kg. Les amendements organiques ont augmenté la teneur en humidité du sol à 24 et 25% pour la tourbe et le biochar respectivement par rapport au témoin. La croissance végétative de la plante a également été améliorée avec les amendements.

Nutripriming with ammonium nitrate improves emergence and root architecture and promotes an increase in nitrogen content in upland rice seedlings

Nitrogen (N) is a highly important macronutrient in the control of several plant development processes. This study was conducted to analyze the nutripriming potential using ammonium nitrate (NH4NO3) to reinforce the emergence and initial development of rice seedlings. Priming treatments included hydropriming and nutripriming using 2, 4 and 6 mM NH4NO3 (−0.01, - 0.02, and −0.03 MPA, respectively) for 16 h at 25 °C. Dry (untreated) seeds were kept as control. All priming treatments reduced the mean emergence time of rice seedlings, including hydropriming. Nevertheless, nutripriming at 6 mM provided an earlier onset of emergency among all the applied treatments. On the other hand, nutripriming with 2 mM NH4NO3 provided greater root length and N–NH4+content in the roots, besides a higher total nitrogen content and glutamine synthetase activity in the aerial part. The parameters related to the architecture of the root system were also influenced by priming, where 2 and 6 mM of NH4NO3 promoted an increase in crossings, length, volume, project area, and tips. Based on the results obtained in this experiment, it can be concluded that nutripriming with NH4NO3 in rice seeds was an effective technique to improve the emergence and initial growth of rice seedlings.

Nitrogen and Phosphorus Accumulation in Horizontal Subsurface Flow Constructed Wetland

The article presents the results of studies aimed at determining the level of accumulation of total nitrogen and total phosphorus in parts of reeds (Phragmites australis (Cav.) Trin. ex Steud.), as well as in a constructed wetland bed. The influence of the vegetative phase and dormancy of plants on the level of accumulation of biogenes in plant parts and in the bed of constructed wetland was investigated. Young plants at the stage of intensive growth were found to contain the most total nitrogen and total phosphorus. The leaves of the common reed, on the other hand, revealed the highest ability for the phytoaccumulation of nitrogen (32.21 gN/kg d.m.). Accumulation of total phosphorus in the leaves of reeds was, on average 1.54 gP/kg d.m. The results of studies on the filtration material filling the beds showed that the surface layer of up to 20 cm in depth was characterized by the highest total nitrogen content and total phosphorus content (average: 12.53 gN/kg d.m. and 3.01 gP/kg d.m.). The accumulation of these compounds decreased along with the depth of the deposit as well as in the direction of the outflow of sewage from the constructed wetland.

Amino acid and chlorin based degradation indicators in freshwater systems

Lakes cover a global area that is about 35 times smaller than the oceans, but carbon burial in lakes and oceans are on the same order of magnitude. Hence, understanding the processes for such high organic carbon burial in lacustrine systems is essential. We applied proxies typically used for marine environments including amino acid (AA) content and their nitrogen stable isotope composition to the water columns and sediments of three lakes that differ in their trophic states and depositions rates of sedimentary terrestrial organic matter. Additionally, we used carbon isotope fingerprinting of AAs to characterise their sources and fates. We show that this set of proxies tracks sources and degradation processes in eutrophic lakes with high sedimentary total organic carbon and nitrogen content. Those lakes also have a high total hydrolysable amino acid (THAA) content as well as higher pigment concentrations. While the Chlorin degradation Index (CI) showed increasing values with depth, the patterns were less consistent for the Degradation Index (DI). In general, all parameters failed to describe degradation in the most oligotrophic lake due to the very low organic carbon and nitrogen content in the sediment. We show that AAs are mostly of autochthonous origin and that AA contribute 5–45% to the organic material in plankton, POM, and sediment. Proxies based on AA for bacterial reworking (ΣV) or trophic level (TL) showed increasing values in the water column but relatively stable values in the sediments. Furthermore, we show that methanotrophic bacteria led to increased values for the bacterial reworking proxy (ΣV) and extraordinarily low δ13C AA values (−30 to −60‰).

Restoration thinning reduces bush encroachment on freehold farmlands in north-central Namibia

Abstract Bush encroachment affects ~45 million ha of Namibia and, without appropriate restoration measures, it negatively affects rangeland productivity and biodiversity. Thinning is a common method to counteract bush encroachment. The thinning strategy applied in north-central Namibia was assessed to examine how effective it has been in reducing bush encroachment. Trees/shrubs were selectively thinned manually, targeting all height classes, except individuals with stem diameters ≥18 cm. We investigated the effects on the vegetation and soil properties using surveys on three freehold farms (in 2016 and 2017) in bush-encroached and previously thinned habitats. Our results revealed significant differences in the mean total nitrogen (TN) content between the treatments; thinned areas had higher TN content which would be beneficial for fast-growing grasses. In the thinned plots, the occurrence probability of red umbrella thorn (Vachellia reficiens Warwa) was significantly reduced, indicating that it was the most harvested species; and umbrella thorn (Vachellia tortilis (Burch.) Brenan spp. heteracantha) was increased, indicating that it favoured reduced densities of dominant species. Natural regeneration was rapid; the tree/shrub abundance in the 0–1-m height class in the thinned area surpassed those in the non-thinned by 34 per cent, ~7.2 years since thinning. Thinning significantly reduced tree/shrub abundances of the 1–3- and >3-m height classes, which was still evident 7.2 years since thinning. Based upon the generalized linear mixed-effects model, tree/shrub counts between treatments may equalize in ~14 and 15 years for the 1–3- and >3-m height classes, respectively. Thinning was effective in reducing tree/shrub abundances and can be used to restore wildlife habitat on the Namibian farmland: however, post-thinning management is required to maintain an open savannah vegetation structure as the 0–1-m height class cohort will eventually grow into mature trees/shrubs.

Unusual green Type Ib–Iab Dniester–type diamond from Ukrainian placers

Among placer diamond occurrences in Ukraine, a group of microdiamonds have been distinguished that have specific morphological, color and spectral characteristics, not observed in other natural diamonds. These diamonds, termed “Dniester–type diamonds”, have tetrahexahedroidal and rhombododecahedroidal morphologies, green coloration, and high concentrations of single–atom, unaggregated nitrogen in the form of C–centers (66–74% of all N atoms), along with low ratios of nitrogen aggregation (0–13% agrregation ratio) and high total nitrogen content (892–1493 atomic ppm). With these characteristics, Dniester–type diamonds are approximate the Type Ib-Iab classification. The predominance of single–atom, unaggregated nitrogen indicates a short residence time under high–temperature conditions. These Dniester–type diamonds have a narrow range of carbon isotopic compositions, from δ13С = -10.52‰ VPDB tо -12.82‰ VPDB (average δ13С = -11.85‰ VPDB). They are distributed in Quaternary and Neogene sediments of the southwestern part of the Ukrainian Shield. This distribution forms a local halo within the Dniester and Southern Bug rivers interfluve and Black Sea beach sediments, approximately 650 km in length. This implies their endemic character and the likely nearby presence of primary source(s) of unknown, possibly non–kimberlitic type.

Kinetics and catalytic efficiency of soil fluorescein diacetate hydrolase under the pesticide parathion stress

Fluorescein diacetate hydrolase (FDA–H) is an accurate biochemical method measuring the total microbial activity in soil, which indicates soil quality under ambient environmental changes such as pesticide parathion (PTH). However, the influence of PTH on the kinetics of FDA–H is still unknown. In this study, fifteen farmland soils were exposed to acute PTH pollution to investigate how the kinetic characteristics of FDA–H change with PTH concentration. Results showed that PTH strongly inhibited the FDA–H activities. The values of maximum reaction velocity (Vmax) ranged from 0.29 to 2.18 × 10−2 mM g−1 soil h−1 and declined by 42.30%–71.01% under PTH stress. The Michaelis constant (Km) values ranged between 2.90 and 14.17 × 10−2 mM and exhibited three forms including unchanged, increased (38.16–242.65%) and decreased (13.41–39.23%) when exposed to PTH. Based on the changes in two kinetic parameters, the inhibition of PTH on FDA–H was classified as three types, i.e., noncompetitive, linear mixed and uncompetitive inhibition. The competitive inhibition constant (Kic) and noncompetitive constant (Kiu) ranged from 0.064 to 0.447 mM and 0.209 to 0.723 mM, respectively, which were larger than the Km in values. The catalytic efficiency (Vmax/Km) of FDA–H is a sensitive integrated parameter to evaluate the PTH toxicity due to the higher inhibition ratio than the Vmax. The PTH toxicity to FDA–H decreased with increase of soil organic matter and total nitrogen contents. This implied that the PTH toxicity could be alleviated by an increasing content of soil organic matter due to its buffering capacity to PTH. Besides, soils with a higher content of total nitrogen could provide stable environment for FDA–H to maintain its functionality under PTH pollution. Thus, the results of this study have great implications to the risk assessment of parathion in soils.

Circulation patterns of biogenic ions in Young Glacial areas.

The paper focuses on the effect of ponds (geographically isolated wetlands) on water quality within internally drained areas in a river catchment. The important part of the study was the point of formation of a periodic hydrographic network of internally drained areas linked with a main river as well as the identification of the circulation pattern of ions in such a system. The aim of the study was to examine the extent to which ponds pollute the main river upon physical connection with it. Research has shown that ponds participate actively in material circulation-including that of water and biogenic ions. The hydrographic network in Young Glacial areas is subject to very large seasonal changes. In the study area, the total length of the stream network in the dry season equaled 12 km, while in the wet season almost 75 km. At the same time, almost 50% of the internally drained areas in the catchment became connected with the surface runoff network. Such large seasonal changes in the hydrographic network yield large changes in stream water chemistry. In the study area, only 6 ponds were linked to the stream network during the dry season, while in the wet season, this number increased to 125. The parts of catchments featuring the largest changes in the hydrographic network as well as the largest number of ponds temporarily linked with surface runoff networks were characterized by a high content of total nitrogen and phosphorus-up to 244.2 kg N km2 per month and 26.2 kg P km2 per month.

Carbon, nitrogen, and aggregation index in Ultisol with 11 years of application of animal manures and mineral fertilizer

Soil erosion in Brazil is very high, and there is need to promote aggregate stability technics to increase the soil organic matter and the soil water infiltration, with a consequent decrease in erosion processes. Applications of animal manure on sandy loam soil may increase carbon (C) and nitrogen (N) contents in soil aggregates, causing increased aggregate stability. This study aimed to evaluate the contents of total organic carbon (TOC) and total nitrogen (TN) as well as the physical properties of a sandy loam soil subjected to 11 years of application animal manure and mineral fertilizer. The experiment was conducted under no-tillage (NT) system with corn (<i>Zea mays</i> L.)/black oat (<i>Avena strigose</i> Schreb.), bean (<i>Phaseolus vulgaris</i> L.)/black oat, and corn/wheat (<i>Triticum</i> spp.) crops. The following treatments were used: control (no fertilization), pig slurry (PS), pig deep litter (DL), cattle slurry (CS), and mineral fertilizer (NPK). Soil aggregates were obtained from undisturbed soil samples collected at soil depths of 0 to 5, 5 to 10, and 10 to 20 cm. Applications of PS, DL, and CS on soil increased TOC and TN contents, and increasing weighted mean diameter (WMD) and geometric mean diameter (GMD) in the topsoil. Use of DL and CS increased TOC at 0 to 5 cm in comparison to PS, NPK, and control. The use of animal manure also resulted in higher TN contents at 0 to 5 and 10 to 20 cm compared to control. The use of animal manure for 11 years under NT reduced the amount of mesoaggregates (2.0 &gt; Ø ≥ 0.25 mm) and microaggregates (Ø &lt; 0.25 mm) and increased GMD in the topsoil in comparison to the NPK and control. The animal manure promoted the dispersion of clays at 5 to 10 and 10 to 20 cm, resulting in lower soil aggregation in depth. Principal component analysis confirmed that animal manure reduced the degree of flocculation, with a consequent decrease in aggregation indexes, as it grouped the manure treatments in opposition to the NPK and control treatments.