Low Nitrate Levels Research Articles

Effect of temperature, nitrate concentration, pH and bicarbonate addition on biomass and lipid accumulation in the sporulating green alga PW95

The mixed effects of temperature (20 °C, 25 °C and 30 °C), nitrate concentration (0.5 mM and 2.0 mM), pH buffer, and bicarbonate addition (trigger) on biomass growth and lipid accumulation were investigated in the environmental alga PW95 during batch experiments in standardized growth medium. PW95 was isolated from coal-bed methane production water and classified as a Chlamydomonas-like species by morphological characterization and phylogenetic analysis (18S, ITS, rbcL). A factorial experimental design tested the mixed effects on PW95 before and after nitrate depletion to determine a low cost, high efficiency combination of treatments for biomass growth and lipid accumulation. Results showed buffer addition affected growth for most of the treatments and bicarbonate trigger had no statistically significant effect on growth and lipid accumulation. PW95 displayed the highest growth rate and chlorophyll content at 30 °C and 2.0 mM nitrate and there was an inverse relation between biomass accumulation and lipid accumulation at the extremes of nitrate concentration and temperature. The combination of higher temperature (30 °C) and lower nitrate level (0.5 mM) without the use of a buffer or bicarbonate addition resulted in maximal daily biomass accumulation (5.30 × 106 cells/mL), high biofuel potential before and after nitrate depletion (27% and 20%), higher biofuel productivity (16 and 15 mg/L/d, respectively), and desirable fatty acid profiles (saturated and unsaturated C16 and C18 chains). Our results indicate an important interaction between low nitrate levels, temperature, and elevated pH for trade-offs between biomass and lipid production in PW95. This work serves as a model to approach and advance the study of physiological responses of novel microalgae to diverse culture conditions that mimic environmental changes for outdoor biofuel production. The most promising conditions for growth and biofuel production were identified for PW95 and this approach can be implemented for other microalgal production systems.

Functional growth, photosynthesis and nutritional property analyses of lettuce grown under different temperature and light intensity

ABSTRACT There is a growing interest in the impact of light intensity and temperature on vegetable growth and dietary quality characteristics. Lettuce (Lactuca sativa L.), as one of the model vegetables in plant factories, was grown under two light levels (G1: 160 µmol m–2 s–1, G2: 200 µmol m–2 s–1) with different day/night temperatures (T1: 20 ± 1°C/15 ± 1°C, T2: 24 ± 1°C/19 ± 1°C) to investigate mutual effects of light intensity and temperature on its growth and quality properties. The results revealed that the T2G2 treatment showed higher plant height, biomass and net photosynthetic rate, while T1G2 resulted in decreased leaf area and lower maximum photochemical efficiency of photosystem II (Fv/Fm) compared to T1G1. Simultaneous increases in light intensity and temperature based on T1G1 significantly increased the contents of anthocyanin, vitamin C (Vc) and soluble protein by 58%, 21% and 172%, respectively. The higher light intensity promoted the nutritional values of lettuce, characterised by lower nitrate level and soluble protein contents. Principal component analysis showed a negative collinearity between the nitrate content and soluble protein and Vc contents. In conclusion, light intensity and temperature co-regulated the lettuce’s growth and development, and their simultaneous increases better for growth and nutritional values of lettuce. These results provide a better understanding of the cultivation of plants in an artificial plant factory while maintaining yield and quality.

Nitrate Levels in Rural Drinking Water in Belize.

Background.Health issues have been associated with the consumption of high levels of nitrates in drinking water. Rural agricultural communities in Belize play a large role in the economic growth of the country. These communities obtain drinking water directly from the ground and may be susceptible to nitrate consumption and at risk of developing diseases associated with nitrates.Objectives.The present study examined nitrate levels in Belize's rural water supply with the aim of assessing its suitability for human and livestock consumption. The study also provides baseline data for monitoring the concentration of nitrates to prevent public health hazards in Belize.Methods.Forty-three (43) water samples from reservoirs, wells, vats, and standpipes were collected from 40 villages in Belize and analyzed for nitrates using the cadmium reduction method. Nitrates were detected with an Orion® AquaMate® 8000 UV-Vis spectrophotometer at 520 nm. The Belize Coastal Zone Management Authority and Institute laboratory analyzed all water samples for nitrates.Results.Except for four water samples from four different sites, all analyzed water samples were found to contain nitrate levels below 10 mg/L. Nitrate levels above 10 mg/L were seen in a few samples in the northern part of the country, probably due to agricultural activities in these areas.Conclusions.Belize's rural drinking water contains low levels of nitrates, except for a few villages where the levels exceeded the acceptable limit of 10 mg/L. Higher levels of nitrates detected in a few villages need regular evaluation and monitoring to avoid public health issues as well as prevent harm to livestock.Competing Interests.The authors declare no competing financial interests.

Spatial Variability and Associated Risk Assessment of Nitrate and Ammonium Concentration in Hail Haor Wetland, Northeastern Bangladesh

Nitrate-nitrogen and ammonium-nitrogen concentration were evaluated to assess the current nutrient condition of an ecologically as well as economically important wetland of Bangladesh. The contamination condition of surface water nitrate and ammonium of Hail Haor wetland was assessed to understand its probable risk to human health using the water samples collected from total-fifty monitoring stations, 25 each for two different seasons within 2018 to 2019. Nitrate concentration was measured using the spectrophotometer by colorimetric method, whereas ammonium was quantified using the micro Kjeldahl's distillation method. Statistical and geo-spatial analysis revealed an extensive understanding of the temporal and spatial variability as well as possible source identification of the nutrients in the studied area. Medium to a low level of nitrate ranging from 0.95 up to 9.25 mg/L and high ammonium with values from 0.32 up to 1.92 mg/L was a sporadic trend observed in wetland water, with low water season having more concentration than that of wet high water season. Hazard quotients (HQ) obtained from wetland water for four individual age groups recognized wetland water to be safe for consumption (HQ<1) based on its nitrate level. Wetlands can provide valuable ecosystem services, conserve the native and exotic wetland inhabitants and mitigate flood along with their purifying properties of nutrient removal to lessen the public health concerns about nitrate-nitrogen in drinking water. Therefore, appropriate rein in measures, incentivizing water use efficiency, and continuous monitoring of water quality will ensure safety for wetland habitats, also may aware of the risks or opportunities associated with using wetland water for both drinking and agricultural use.

Soil nitrate leaching under grazed cool-season grass pastures of the North Central US.

Nitrate leaching from agricultural cropping systems contributes to widespread and devastating eutrophication of water bodies globally. In the North Central USA, this problem is acute, with millions of dollars spent annually in efforts to clean up recreational and drinking water. The frequent soil disturbance and exogenous nitrogen (N) amendments applied in annual cropping systems make them major sources of ground- and surface-water nitrate pollution. Perennial grasslands under managed livestock grazing have been touted for their ability to retain soils and nutrients while simultaneously providing milk and meat to society. The present study provides an evaluation of the peer-reviewed literature addressing nitrate leaching loads beneath corn, pasture and prairie in temperate humid and sub-humid regions of the US, with a focus on cool-season grass pastures. Inputs of exogenous N to these agroecosystems comes from wet and dry deposition, livestock manure from imported feed, biological fixation and inorganic N fertilizer. Nitrate loads were highest beneath corn and lowest beneath restored prairie and switchgrass managed for bioenergy. Cool-season grass pastures had relatively low levels of nitrate leaching loads where little or no N was applied. However, where grazed perennial grasslands had inorganic N applied, nitrate leaching loads rivaled those of corn in some cases. When producing milk and meat from livestock, grazed perennial cool-season grass pastures should reduce nitrate leaching loads compared to growing corn that is used to feed livestock in confinement. However, cool-season grass pastures can lose significant nitrate to leaching with moderate- to high-levels of exogenous N inputs. © 2020 Society of Chemical Industry.

Organic Farming Sharpens Plant Defenses in the Field.

Plants deploy a variety of chemical and physical defenses to protect themselves against herbivores and pathogens. Organic farming seeks to enhance these responses by improving soil quality, ultimately altering bottom up regulation of plant defenses. While laboratory studies suggest this approach is effective, it remains unclear whether organic agriculture encourages more-active plant defenses under real-world conditions. Working on the farms of cooperating growers, we examined gene expression in the leaves of two potato (Solanum tuberosum) varieties, grown on organic vs. conventional farms. For one variety, Norkotah, we found significantly heightened initiation of genes associated with plant-defense pathways in plants grown in organic vs. conventional fields. Organic Norkotah fields exhibited lower levels of nitrate in soil and of nitrogen in plant foliage, alongside differences in communities of soil bacteria, suggesting possible links between soil management and observed differences in plant defenses. Additionally, numbers of predatory and phloem-feeding insects were higher in organic than conventional fields. A second potato variety, Alturas, which is generally grown using fewer inputs and in poorer-quality soils, exhibited lower overall herbivore and predator numbers, few differences in soil ecology, and no differences in gene-activity in organic and conventional farming systems. Altogether, our results suggest that organic farming has the potential to increase plants' resistance to herbivores, possibly facilitating reduced need for insecticide applications. These benefits appear to be mediated by plant variety and/or farming context.

Effects of Nitrate Enrichment on Respiration, Photosynthesis, and Fatty Acid Composition of Reef Coral Pocillopora damicornis Larvae

In the foreseeable future, coastal coral reef ecosystems are likely to face further increases in eutrophication. Lipids and fatty acids (FAs), as important components of corals, are becoming a hot topic to study the effects of eutrophication on corals. This study investigated the effects of nitrate (NO3-) enrichment (0, 5, 10, 20, and 40 μM) on the respiration, photosynthesis, and FA compositions of Pocillopora damicornis larvae. Our results showed that saturated fatty acids (SFAs) were the most abundant in P. damicornis larvae over all treatment groups, followed by polyunsaturated fatty acids (PUFAs). The unsaturated to saturated fatty acid ratio (U/S) and unsaturation index (UI) reduced at low nitrate concentrations (20 μM). The UI and U/S levels were elevated due to the increased PUFAs levels and decreased SFA levels at higher nitrate concentrations. Compared with the N5 and N10 groups, the fluidity of the biomembrane of the larvae did not continue to decrease but instead increased at higher nitrate concentrations, indicating that the biomembrane restructuring in the larvae may have become ineffective. Moreover, respiration increased and the consumption of numerous lipids led to a significant decrease in TFAs. These could adversely affect the dispersal, settlement, and development of larvae. Overall, P. damicornis larvae can adapt to low levels of nitrate (< 10 μM) due to biomembrane restructuring through changes in FA composition. However, negative effects occur in larvae when nitrate exceeds 20 μM.

Revealing the role of nitrate on sulfide removal coupled with bioenergy production in Chlamydomonas sp. Tai-03: Metabolic pathways and mechanisms

Recently, simultaneous sulfide removal and bioenergy production by microalgal treatment have attracted growing attention. However, the response of nitrogen metabolism to the sulfide-removal process has yet to be explored. Here, variable levels of sulfide could be completely removed by Chlamydomonas sp. Tai-03 under both high and low nitrate conditions in synthetic wastewaters. The highest sulfide removal rate of 5.56 mg-S L−1 h−1 was achieved with the addition of 100 mg L−1 sulfide in the presence of high nitrate. Meanwhile, sulfide was chemically oxidized to sulfate and then ingested by microalgae. Interestingly, sulfide-removal efficiency critically depended on nitrate concentration. Sulfide can also enhance the ability of microalgae to assimilate nitrogen. Based on the analysis of sulfur- and nitrogen-related metabolic profiling, serine as a precursor decreased by 94 % under low levels of nitrate, which induced the significant inhibition of cysteine and methionine biosynthesis. The results indicated that nitrogen source played a critical role in the sulfur cycle because of the positive relationship between the aforementioned metabolic processes and nitrate concentration. Additionally, sulfide can improve lipid and carbohydrate productivity under high levels of nitrate. This study enhances our understanding of the mechanisms underlying the simultaneous removal of sulfide and alternative bioenergy production.

First Records of Morphological Diversity and Ecology of Periphytic Cyanobacteria from Tukun River, Penang Forest Reserve, Malaysia.

Despite the abundance of streams and rivers in Malaysia, the algal communities of these lotic ecosystems have remained largely unstudied. In a one-year floristic survey conducted from December 2014, 24 cyanobacterial morphospecies were identified for the first time from Tukun River, Penang Forest Reserve. Ten morphospecies were identified directly from field specimens while the remaining 14 morphospecies were identified only in cultures derived from the field samples. A total of 17 morphospecies; Leptolyngbya cf. boryana, L. cf. foveolarum, L. valderiana, Chroococcus cf. cohaerens, C. cf. disperses, C. cf. membraninus, C. cf. minutus, C. cf. varius, Gloeocapsopsis cf. crepidinum, Geitlerinema cf. tenuius, Phormidium simplicissimum, Dolichospermum sp., Fischerella sp., Homoeoptyche repens, Nematoplaca inscrustans, Scytonema hofmanii and S. stuposum are new records for Malaysia. Crusts were the most dominant macroscopic forms (seven morphospecies) followed by mats (three morphospecies). Scytonema was the most frequently encountered genus, occurring at 8/9 sampling sites. The presence of heterocytous cyanobacteria (S. stuposum, S. hofmanni) in 8/9 sampling sites is consistent with the low nitrate levels (< 0.74 mg/L) recorded throughout the study stream. Chroococcales were dominant in both upper and middle parts of the stream. The morphospecies present showed distinct distribution patterns despite apparently minimal variations in ecological parameters such as temperature, dissolved oxygen, pH and conductivity between the sampling sites. This study provides important new baseline information in understanding the diversity of periphytic cyanobacteria not only in Penang Island but more widely in Malaysia. This information can make a useful contribution in biomonitoring stream health.

Community composition and photosynthetic physiology of phytoplankton in the western subarctic Pacific near the Kuril Islands with special reference to iron availability.

The western subarctic Pacific (WSP) is known as one of the most productive regions among the world's oceans in spring. However, its oceanic waters are also known as a High Nutrient, Low Chlorophyll (HNLC) region during summer due to low iron (Fe) availability in seawater. Indeed, recent studies have demonstrated that the distribution of Fe in the WSP is complex and heterogeneous. This study thus investigated the effects of Fe availability on the community composition and photophysiology of surface phytoplankton from coastal to offshore waters in the WSP in the summer of 2014. Although relatively high concentrations (>2 mg m-3) of chlorophyll (chl) a were found in the Sea of Okhotsk and some coastal waters, low chl a concentrations (<1 mg m-3) were commonly observed in offshore waters. Based on dissolved Fe and macronutrient concentrations, we deduced that low Fe availability limited phytoplankton growth in offshore waters, whereas low silicate and/or nitrate levels limited growth in the shelf areas. Scanning electron microscopy also revealed that the centric diatom Chaetoceros exclusively dominated the diatom assemblages in the shelf and coexisted with pennate diatoms in offshore waters, respectively. Primary productivity in surface waters was negatively correlated with the bottom of the euphotic layer or the light saturation index of the photosynthesis-irradiance curve, which indicates that the phytoplankton assemblages were well acclimated to in situ light conditions regardless of the water masses.

Proximate Analysis and Safety Profile of Farmed Edible Bird's Nest in Malaysia and Its Effect on Cancer Cells.

Edible bird's nest (EBN) which is solidified swiftlet's saliva contains high nutritional value. It is widely consumed in countries like Malaysia, Indonesia, and Thailand. However, previous proximate analysis of Malaysia EBN was not representative of all the regions in Malaysia. In recent years, safety issues such as high nitrate and nitrite contents, presence of heavy metal, adulteration, fungal infection, and cancer cell stimulation were associated with EBN. Hence, this study aimed to determine the proximate analysis, safety profile during normal weather and hazy periods, and its effect on cancer cells stimulation in Malaysia-farmed EBN. Seven raw cleaned EBN samples were sourced from 6 different regions in Malaysia. Proximate analysis and safety profile were performed using official AOCA methods and Malaysian Standard. High protein (53.03–56.37%) and carbohydrate content (27.97–31.68%) with an acceptable level of moisture (10.8–14.04%) and ash (2.22–3.38%) were reported. A good safety profile was obtained with low nitrite and nitrate levels, with undetectable heavy metals and no significant growth of pathogenic microorganism except mould. Epidermal growth factor was detected but below the quantification level with the chicken EGF ELISA kit. The microculture tetrazolium (MTT) assay was performed for growth stimulation assessment comparing human EGF and EBN. There was no significant cell growth observed in cancer cells after EBN treatment. In conclusion, EBN Malaysia has a good nutritional profile, free of heavy metals, and an acceptable level of nitrate, nitrite, and microorganism profile except for mould contents. Furthermore, the in vitro study indicated that EBN was not associated with cancer cell growth.

Nitrates in Groundwater of Small Shallow Aquifers in the Western Side of Hoya de Huesca (NE Spain)

Nitrate is one of the most common groundwater contaminants in rural areas. In this work, the presence of high levels of nitrate in groundwater of the aquifers of the west part of Hoya de Huesca County (NE Spain) has been studied by coupling hydrogeological information with water sampling techniques through a wide areal sampling of 90 surface water and groundwater points belonging to several aquifers. The results showed a general hydrochemistry of calcium carbonate to calcium sulfate waters. Unlike other case studies in Mediterranean areas, in which nitrate pollution was associated with irrigated crops, the highest concentrations in the present study were found in dry farming areas in which winter cereal is grown. A monthly nitrate level monitoring, conducted in 21 selected points between 2016 and 2017, showed that the nitrate evolution pattern followed the N fertilizer application schedules in the sampling points in which the highest concentrations were recorded, whereas an annual regularity could be observed in the sampling points with low nitrate levels. The compilation of data for 16 selected points since 1990 shows that the problem is persistent and points to the need of implementing new aquifer pollution control measures, since the ones currently in force have not been successful.

Are macroinvertebrate traits reliable indicators of specific agrichemicals?

Abstract Determining the extent of freshwater contamination by agrichemicals is a major challenge. Biological indicators have been proposed as indirect measures of contaminants that can be used to reduce chemical monitoring costs by identifying pollution hotspots that warrant thorough chemical testing. Many general indicators are based on taxonomic properties of aquatic macroinvertebrate communities. However, it has been suggested that metrics based on traits, rather than taxa, can be used to develop more chemical-specific and efficient indicators. Here, we investigate whether macroinvertebrate family-level traits can be used as simple indicators of elevated levels of specific pollutants in farmland drainage ditches, to reveal areas in need of further chemical monitoring. We selected seven traits—body size, body armouring, feeding guild, habit, oxygen acquisition, dispersal mode, and voltinism—that we predicted would influence sensitivity to nitrate, to the two herbicides atrazine and glyphosate, and to neonicotinoid insecticides, and tested whether any trait-chemical relationships were strong enough to be reliable bioindicators. We collected macroinvertebrate samples and water samples for agrichemical analyses from 27 farmland ditches in Eastern Ontario, Canada. We indexed the sensitivity of each sampled macroinvertebrate family to the concentration of each agrichemical, using coefficients from multiple logistic regressions of family absence/presence on the concentrations of the four agrichemicals. We reduced the seven traits predicted to influence sensitivity to four—body armouring, oxygen acquisition, dispersal mode, and voltinism—after examining their inter-dependencies. We then tested for cross-family relationships between sensitivity to each chemical and the trait categories for each macroinvertebrate family. Two traits, oxygen acquisition and dispersal mode, were significantly associated with two agrichemical sensitivity coefficients: nitrate sensitivity was associated with mode of oxygen acquisition, with atmospheric breathers having a higher mean sensitivity coefficient than dissolved-oxygen breathers, and glyphosate sensitivity was related to dispersal mode, with passive dispersers having a higher mean sensitivity coefficient than active dispersers. However, inspection of these relationships revealed that the responses lacked enough consistency across families to be reliable, chemical-specific indicators. Instead, a taxa-level, post-hoc analysis indicated that further work should be conducted to determine whether there are individual taxa whose presence at a site is a strong indicator of a lack or low levels of certain contaminants. In particular, the presence of Corixidae appears to indicate low ditch nitrate levels. Overall, however, our results combined with previous work suggest that we are unlikely to find chemical-specific macroinvertebrate indicators that are more efficient than a rigorous chemical sampling scheme.

Do NH4:NO3 ratio and harvest time affect celery (Apium graveolens) productivity and product quality?

Abstract Due to the remarkable health benefits of celery (Apium graveolens), its consumption has increased over time. A partial substitution of NO3 − with NH4 + is recommended to limit the accumulation of NO3 − in leafy vegetables. Hence, a factorial experiment with two factors, consisting of six treatments as combinations of three NH4:NO3 ratios (0:100, 20:80 and 40:60) in nutrient solutions and two harvesting times (in the morning and in the evening), was conducted on celery plants in a soilless culture system. The results showed that 100% NO3 as a sole N source significantly increased plant height, leaf number, chlorophyll, fresh weight, N, K, Ca, Mg, Fe, Mn, Zn, protein, dietary fibre, soluble sugars, nitrate, vitamin C, α-carotene, β-carotene and lutein of celery plants compared to either 80 or 60% NO3. However, this increase was not significant compared to 20% NH4:80% NO3 in terms of leaf number, fresh yield, N, Mg, Mn, protein, soluble sugars, vitamin C and α-carotene. Harvesting in the evening significantly increased K, Mg, Fe, soluble sugars, α-carotene and β-carotene, and lowered the nitrate level in celery plants. In conclusion, partial replacement of 20% NO3-N with 20% NH4-N and evening harvesting are recommended for a greater fresh yield, higher quality, and lower nitrate level.

Utilizing genome-scale models to optimize nutrient supply for sustained algal growth and lipid productivity

Nutrient availability is critical for growth of algae and other microbes used for generating valuable biochemical products. Determining the optimal levels of nutrient supplies to cultures can eliminate feeding of excess nutrients, lowering production costs and reducing nutrient pollution into the environment. With the advent of omics and bioinformatics methods, it is now possible to construct genome-scale models that accurately describe the metabolism of microorganisms. In this study, a genome-scale model of the green alga Chlorella vulgaris (iCZ946) was applied to predict feeding of multiple nutrients, including nitrate and glucose, under both autotrophic and heterotrophic conditions. The objective function was changed from optimizing growth to instead minimizing nitrate and glucose uptake rates, enabling predictions of feed rates for these nutrients. The metabolic model control (MMC) algorithm was validated for autotrophic growth, saving 18% nitrate while sustaining algal growth. Additionally, we obtained similar growth profiles by simultaneously controlling glucose and nitrate supplies under heterotrophic conditions for both high and low levels of glucose and nitrate. Finally, the nitrate supply was controlled in order to retain protein and chlorophyll synthesis, albeit at a lower rate, under nitrogen-limiting conditions. This model-driven cultivation strategy doubled the total volumetric yield of biomass, increased fatty acid methyl ester (FAME) yield by 61%, and enhanced lutein yield nearly 3 fold compared to nitrogen starvation. This study introduces a control methodology that integrates omics data and genome-scale models in order to optimize nutrient supplies based on the metabolic state of algal cells in different nutrient environments. This approach could transform bioprocessing control into a systems biology-based paradigm suitable for a wide range of species in order to limit nutrient inputs, reduce processing costs, and optimize biomanufacturing for the next generation of desirable biotechnology products.

Biological potency of soil, yelding ability and quality of potato depending on the use of microbiologic specimen

The article presents the results of research on the effectiveness of microbiologic specimen against the background of various doses of mineral fertilizers, and without them. The results were obtained in two short-term experiments for the period from 2015 to 2018.Goal of research: to increase the productivity and quality of potatoes with the integrated use of full and reduced by 30 and 50% doses of mineral fertilizers in combination with various microbiologic specimen by increasing the biological activity of the soil and better nutrient absorption.In the field test (2015-2016, sod-podzolic sandy soil), the yield of potatoes was 24.1-27.9 t / ha (when using mineral fertilizers N45-90P45-90K60-120). When N45P45K60 was combined with preplant treatment of tubers with microbiologic specimen (Azolen, Agrinos «1» and Biocomposite-correct), it increased by 27.6-28.5%, including the increase from microbiologic specimen - 3.5-4.4 t / ha or 14.5-18.3%. In the field test (2016 and 2017-2018, sod-podzolic sandy soil), the maximum yield of potatoes (34.0-35.7 t / ha) was obtained using the microbiologic specimen Extrasol both separately for preplant treatment of tubers, and in combination with foliar application of Agrinos «2» and Extrasol on the background of the full dose of fertilizers N90P90K90. In this case, the yield increase from the biologic specimen was 6.5-8.2 t / ha or 23.6-29.8%.In the variant with a 30% reduced NPK dose and the use of Agrinos [N60P60K60 + Agrinos 1+2 (5+2.5 l / ha)]: the yield level was 4.6 t / ha (17%) higher a full dose of NPK. At the same time high starchiness and vitamin C content, excellent culinary qualities, low levels of nitrates in products; conditional income was 42.3 thousand rubles / ha higher than NPK background, low cost (6.8 rubles / kg), high cost recovery (3.25) and profitability of production 64% were observed.

Use of raw and composted poultry litter in lettuce produced under field conditions: microbiological quality and safety assessment

Lettuce (Lactuca sativa L.) constitutes one the most important vegetable crops worldwide. Poultry litter is being applied as an economically suitable alternative to nitrogen fertilizers in lettuce cultivation. However, little is known about the effects of this practice over this fresh product safety that is usually consumed as a salad. The aim of this work was to determine the microbiological quality and the nitrate content in lettuce produced, under field conditions, using either raw or composted poultry litter, coming from the same original batch. Two experiments were conducted in the experimental field of Facultad de Ciencias Agrarias (UNL, Santa Fe, Argentina) to assess the effects of recently extracted poultry litter that consisted of broiler chicken manure plus rice husk, or composted for 12 mo. The application amounts were: 20 T ha-1 (T1); 40 T ha-1 (T2); and no application of manure (T). Increasing the applied quantities had also increased the health risk associated with lettuce consumption, due to higher nitrate levels and microbial contamination. However, these risks were reduced by composting the material. Even when lettuce contamination with faecal bacteria was mainly due to the use of poultry litter, the number and incidence of pathogens were reduced when properly composted manure was applied instead of raw one. Increasing the dose of poultry litter applied also increases the health risk in lettuce. Though, when the material is properly composted, its fertilizing capacity is maintained, giving proper yields with lower nitrate levels and microbial contamination by enterobacteria.

Physical factors limiting access to clean groundwater in Tanzania villages

Abstract Low yield, poor water quality, and nonfunctional infrastructure impede physical access to clean groundwater in rural Tanzania. We studied boreholes in 45 villages as part of a rehabilitation program led by the Global Water Institute at The Ohio State University. Villages were chosen because their groundwater supply systems were inoperative or unsustainable. The most common cause was pump failure, which occurred in more than half of the villages. Even if broken pumps were repaired or replaced, low pump capacities and potential yields would limit physical access in many villages. Low potential yield is often mistaken for a broken pump, but easily diagnosed with a pump test. Pump test records were available for only eight villages, highlighting the need for more testing and data accessibility. One-third of the villages had low water quality. In comparison to secondary water sources such as springs, impoundments, and dug wells, boreholes tended to have lower levels of nitrate and fecal coliform, greater total dissolved solids, and similar fluoride levels. In many villages, groundwater is the only viable water resource to support development, but drilling records and hydrogeologic data are sparse. We recommend better digital data archiving with governmental water supply authorities and the assessment of potential well yields and sustainable yields.

Proteomic Profiling for Metabolic Pathways Involved in Interactive Effects of Elevated Carbon Dioxide and Nitrogen on Leaf Growth in a Perennial Grass Species

Elevated atmospheric CO2 and nitrogen are major environmental factors affecting shoot growth. The objectives of this study are to determine the interactive effects of elevated CO2 and nitrogen on leaf growth in tall fescue ( Festuca arundinacea) and to identify major proteins and associated metabolic pathways underlying CO2-regulation of leaf growth under insufficient and sufficient nitrate conditions using proteomic analysis. Plants of tall fescue treated with low nitrate level (0.25 mM, LN), moderate nitrate level (4 mM, MN) and high nitrate level (32 mM, HN) were exposed to ambient (400 μmol mol-1) and elevated (800 μmol mol-1) CO2 concentrations in environment-controlled growth chambers. Increased atmospheric CO2 concentration increased leaf length and shoot biomass, which corresponded to increased content of indo-acetic acid, gibberellic acid, cytokinins and reduced content of abscisic acid under sufficient nitrate conditions (MN and HN conditions). Low nitrate supply limited shoot growth and hormonal responses to elevated CO2. Proteomic analysis of plants exposed to elevated CO2 under LN and MN conditions demonstrated the increases in the abundance of many proteins due to elevated CO2 under MN condition involved with cell cycle and proliferation, transcription and translation, photosynthesis (ribosomal and chlorophyll a/b-binding proteins), amino acids synthesis, sucrose and starch metabolism, as well as ABA signaling pathways (ABA-induced proteins). Our results revealed major proteins and associated metabolic pathways associated with the interactive effects of elevated CO2 and nitrate regulating leaf growth in a perennial grass species.

Spatiotemporal Sediment Nutrient Dynamics of Kware Lake, Nigeria

Kware Lake provides life to various forms of aqua flora and fauna, livelihood for fishermen community and food for the local populace. The study was conducted to evaluate nutrient dynamics of the lake’s sediment for a period of 12 months (June 2014 to May 2015). Results reveal that some of the variables studied did not show any variation due to space and time but electrical conductivity (EC), phosphate (PO43-), potassium, sodium and clay texture were able to vary according to months, seasons and stations. They recorded range of 101.3-113 µs/cm, 0.97-1.24 g/Kg, 0.29-0.37 g/kg, 0.62-0.77 g/kg, and 13-14 g/kg respectively. Results therefore suggest and confirmed that sediment has a high accumulation of phosphate, due to decomposition on the sediment bed and low nitrate level in sediment than in surface water.