Predicting Cyanobacteria dominance in lakes

2001 ◽  
Vol 58 (10) ◽  
pp. 1905-1908 ◽  
Author(s):  
John A Downing ◽  
Susan B Watson ◽  
Edward McCauley
Keyword(s):  
Field Experiments ◽  
Nutrient Concentrations ◽  
Strongly Correlated ◽  
Total N ◽  
Algae Biomass ◽  
Cyanobacteria Blooms ◽  
Freshwater Resource ◽  
Toxic Blooms ◽  
Total P ◽  
Controversial Concept

A controversial precept of aquatic ecology asserts that low ratios of nitrogen to phosphorus (N:P) lead to noxious and sometimes toxic blooms of Cyanobacteria. Cyanobacteria dominance is a major risk to human and ecosystem health. The stoichiometric control of Cyanobacteria therefore has become central to freshwater resource management. This controversial concept is based on observed Cyanobacteria dominance in lakes with low N:P and the results of lab and field experiments. Here we analyze data from 99 of the temperate zone's most studied lakes and show that this model is flawed. We show that the risk of water quality degradation by Cyanobacteria blooms is more strongly correlated with variation in total P, total N, or standing algae biomass than the ratio of N:P. Risks associated with Cyanobacteria are therefore less associated with N:P ratios than a simple increase in nutrient concentrations and algal biomass.

Constituents of Bull Seminal Plasma

1954 ◽  
Vol 31 (4) ◽  
pp. 561-572
Author(s):  
LORD ROTHSCHILD ◽  
H. BARNES
Keyword(s):  
Seminal Plasma ◽  
Freezing Point ◽  
Average Concentration ◽  
Alternative Methods ◽  
Strongly Correlated ◽  
Sodium Potassium ◽  
Total N ◽  
Electrometric Titration ◽  
Sodium And Potassium ◽  
Total P

1. The concentrations of the main inorganic and certain organic constituents of bull seminal plasma have been examined. The average concentrations, in mg./100 ml., were: Sodium 258 Chloride 175 Potassium 172 Citrate 620 Calcium 37 Fructose 460 Magnesium 8 Total N 877 Iron 2 Total P 57 2. Sodium and potassium were found to be inversely correlated, r= -0.86, p<0.001. 3. Calcium, chloride, fructose, citrate and total nitrogen were also strongly correlated (p<0.001), in such a way that a knowledge of the concentration of any one of the constituents enabled the average concentration of the other four in the sample to be predicted with considerable accuracy. 4. Sodium, potassium and chloride were estimated by standard chemical methods and with the flame photometer (sodium and potassium) and by electrometric titration (chloride). The applicability of the alternative methods of estimation, which require very small quantities of seminal plasma, has been examined and is discussed. 5. The freezing-point depression, Δ, of bull seminal plasma was -0.533, standard error of mean, 0.005. 6. The Δ's of a number of laboratory and field diluents were also examined; with two exceptions they were found to vary markedly from Δ for bull seminal plasma.

scholarly journals Window phase analysis of nutrient losses from a typical rice-planting area in the Yangtze river delta region of China

2020 ◽  
Author(s):  
Shuang He ◽  
Fayong Li ◽  
XINQIANG LIANG ◽  
Hua Li ◽  
Sheng Wang ◽  
...  
Keyword(s):  
Stream Water ◽  
Nutrient Loss ◽  
Nutrient Concentrations ◽  
Self Organizing Map ◽  
Delta Region ◽  
Observation Study ◽  
Total N ◽  
Nutrient Runoff ◽  
Runoff Losses ◽  
Total P

Abstract Background: Rice paddy wetlands may serve as a nutrient source or sink in agricultural ecosystems. However, the pattern of nutrient loss on a watershed scale is not clear. A year-round on-site observation study based on 6-h intervals was conducted. Rainfall, temperature, runoff nutrient concentrations, and adjacent stream water samples were automatically monitored to uncover the temporal changes in the runoff losses of the predominant nutrient proxies (total N and total P) from a typical rice-planting area (120 ha) in the Yangtze delta region of China. Results: A high total N concentration in the rice-planting area was observed during the rice-planting season; however, significant fluctuation in the total P was evident throughout the year. The Δtotal N (drainage minus stream) parameter showed negative values with a mean of −0.25 mg L -1 , while Δtotal P showed positive values with a mean of 0.06 mg L −1 . The annual average N and P runoff from paddy field were 11.6 kg ha −1 and 1.5 kg ha −1 , respectively. The window phases for the total N loss were mainly concentrated in the rice-growing season. However, the window phase for the total P loss was more dispersive throughout the year. No apparent relationships were found between rainfall and N and P concentrations by self-organizing map analysis. Conclusions: The high-resolution monitoring, in this study, suggested that nutrient loss loading rather than nutrient concentration, was strongly related to surface runoff Therefore, fertilization before high-intensity rainfall should be avoided to mitigate the nutrient runoff losses and maintain the rice wetland eco-function.

scholarly journals Effects of boron and vermicompost on growth, yield and nutrient content of Chilli (Capsicum annum L.)

2021 ◽  
Vol 6 (1) ◽  
pp. 31-36
Author(s):  
KS Nawrin ◽  
MJ Uddin ◽  
AHMZ Ali ◽  
MK Rahman
Keyword(s):  
Leaf Area ◽  
Growth Yield ◽  
Dry Weight ◽  
Nutrient Content ◽  
Growth And Yield ◽  
Nutrient Concentrations ◽  
Nutrient Accumulation ◽  
Total N ◽  
Capsicum Annum ◽  
Total P

The effects of boron (B) and vermicompost (VC) on growth and yield of Chilli (Capsicum annum L.) and nutrient accumulation in its fruits was examined. The highest plant height (22 cm), leaf number per plant (73), leaf area (502.53 cm2/plant), dry weight (22.27g/plant), fruit length (8.97cm), fruit number per plant (6), fruit yield (11.76 g/plant) were recorded in B0.5 kg/ha + VC5 ton/ha at harvest. The results of growth and yield of Chilli varied significantly (p<0.05) and increased with time. The total nutrient concentrations in the fruits were measured and varied significantly (p<0.05). The highest concentration of total P (0.028 %), K (2.50%), S (0.20 %), Cu (8.0 mg/kg), Fe (410 mg/kg) and Mn (0.80 mg/kg) in the fruit were observed in B0.5 kg/ha +VC5 ton/ha treatment and total N (0.41 %) and Zn (3.50 mg/kg) were found in B1.5 kg/ha + VC5 ton/ha treatment. The overall best growth, yield and nutrient accumulation in the fruits of Chilli was achieved in B0.5 kg/ha + VC5 t/ha treatment. J. Biodivers. Conserv. Bioresour. Manag. 2020, 6(1): 31-36

Nutrient status of Lake Liddel, New South Wales: mass loadings of nitrogen and phosphurus, industrial modification, and trophic state

1992 ◽  
Vol 43 (2) ◽  
pp. 443 ◽  
Author(s):  
RN Royle ◽  
RJ King
Keyword(s):  
Point Source ◽  
New South ◽  
Nutrient Status ◽  
Nutrient Concentrations ◽  
Nitrogen And Phosphorus ◽  
Total N ◽  
South Wales ◽  
Annual Total ◽  
The Mean ◽  
Total P

The concentrations of nitratehitrite-N, Kjeldahl-N and total P in point-source additions to and losses from Lake Liddell (32° 22'S,150° 1'E) were measured fortnightly from September 1987 to September 1988. These data were used in conjunction with flow-rate data to construct a nitrogen and phosphorus budget from Lake Liddell. The annual net point-source loadings of nitrogen and phosphorus were 23 400 and 5700 kg, respectively. There was little relationship between changes in lake nutrient concentrations and fortnightly mass loadings. The mean molar N: P ratio for point source mass additions was 13: 1, whereas that within the lake was 33: 1. These features indicate that within-lake processes were the dominant processes in determining lake nutrient concentrations. Retention in the sediments of a greater proportion of the total P pool than of the total-N pool appeared to be one of these processes. The use of Lake Liddell water in power-station operations resulted in substantial increases in nitrate/ nitrite-N and total-P concentrations in waters returned to the lake. The use of Dillon's model to predict mean annual total-P concentrations from mass loadings indicates that Lake Liddell is on the border between mesotrophic and eutrophic states.

scholarly journals Effects of copper and vermicompost on growth and yield of cowpea (Vigna unguiculata L.) Walp and nutrient accumulation in its fruits

2020 ◽  
Vol 5 (2) ◽  
pp. 13-18
Author(s):  
AT Sharif ◽  
AHMZ Ali ◽  
MK Rahman
Keyword(s):  
Leaf Area ◽  
Plant Height ◽  
Vigna Unguiculata ◽  
Growth Yield ◽  
Dry Weight ◽  
Growth And Yield ◽  
Nutrient Concentrations ◽  
Nutrient Accumulation ◽  
Total N ◽  
Total P

The effects of copper (Cu) and vermicompost (VC) on growth and yield of cowpea (Vigna unguiculata L.) Walp and nutrient accumulation in its fruits was examined. Eight treatments of Cu and VC were used. The highest plant height (226.67 cm), leaf number per plant (86.33), leaf area (174.12 cm2/plant), dry weight (13.98 g/plant), fruit length (52.4 cm), fruit number per plant (6), and fruit yield (5.65 g/plant) were recorded in Cu0.5 kg/ha + VC5 ton/ha treatment at harvest. The results of growth and yield of cowpea varied significantly (p≤ 0.05) and increased with time. The total nutrient concentrations in the fruits were measured and varied significantly (p≤ 0.05). The highest concentration of total P (0.79%), K (4.14%), S (0.42%), Cu (27 mg/kg), Fe (640 mg/kg) and Mn (59 mg/kg) in the fruits were observed in Cu0.5 kg/ha + VC5 ton/ha treatment and total N (4.29%) and Zn (88 mg/kg) were found in Cu1.5 kg/ha + VC5 ton/ha treatment. The overall best growth, yield and nutrient accumulation in the fruits of cowpea were achieved in Cu0.5 kg/ha + VC5 treatment. J. Biodivers. Conserv. Bioresour. Manag. 2019, 5(2): 13-18

scholarly journals Scale issues for assessment of nutrient leaching from agricultural land in Latvia

2012 ◽  
Vol 43 (4) ◽  
pp. 383-399 ◽  
Author(s):  
Ainis Lagzdins ◽  
Viesturs Jansons ◽  
Ritvars Sudars ◽  
Kaspars Abramenko
Keyword(s):  
Water Quality ◽  
Classification System ◽  
Agricultural Land ◽  
Pollution Monitoring ◽  
Nutrient Concentrations ◽  
Total N ◽  
Small Catchment ◽  
Total P ◽  
Term Data

This paper deals with water quality assessment and recommendations for a classification system based on nitrogen (N) and phosphorus (P) concentrations. In order to evaluate the influence of agricultural intensity, climate and hydrology on water quality, the long-term data (from 1995 to 2009) collected in three Latvian diffuse pollution monitoring sites (Berze, Mellupite and Vienziemite) were analysed. Measurements were carried out within areas where agriculture was the main source of diffuse nutrient loading at four spatial scales, i.e. experimental plot, drainage field, small catchment and river. The available long-term data series shows large variations in nutrient concentrations, depending on the intensity of agricultural production system and the scale of measurements. The concentrations of total N are higher at the plot scale, decreasing when the spatial scale of measurements increase. The proposed simplified classification system (five classes) was based upon the assumption that good chemical status for rivers in agricultural areas represent concentrations of total N &lt; 1.5 mg L−1 and total P &lt; 0.075 mg L−1, while in small catchments total N &lt; 2.5 mg L−1 and total P &lt; 0.050 mg L−1 and in subsurface drainage water total N &lt; 5.5 mg L−1 and total P &lt; 0.020 mg L−1.

Eutrophication of agricultural streams: defining nutrient concentrations to protect ecological condition

2008 ◽  
Vol 58 (11) ◽  
pp. 2203-2210 ◽  
Author(s):  
Patricia A. Chambers ◽  
C. Vis ◽  
R. B. Brua ◽  
M. Guy ◽  
J. M. Culp ◽  
...  
Keyword(s):  
Management Practices ◽  
Ecological Condition ◽  
Agricultural Landscapes ◽  
Nutrient Concentrations ◽  
Total N ◽  
Beneficial Management Practices ◽  
Agricultural Streams ◽  
Abundance And Diversity ◽  
Total P

Inputs of nutrients (phosphorus, P, and nitrogen, N) to coastal and fresh waters can accelerate eutrophication, resulting in excessive aquatic plant growth, depletion of oxygen, and deleterious changes in abundance and diversity of organisms. Using long-term (∼1995–2005) monitoring data from agriculturally-dominated watersheds in southern Ontario and Quebec, Canada, we developed and tested several approaches for setting targets for N and P. Our research showed that it is possible to set scientifically-credible targets for total P and total N to protect ecological condition of streams in agricultural landscapes, and define achievable targets attainable following adoption of beneficial management practices.

scholarly journals The impact of intensive dairy farming on the leaching losses of nitrogen and phosphorus from a mole and pipe drained soil

2003 ◽  
pp. 179-184 ◽  
Author(s):  
D.J. Houlbrooke ◽  
D.J. Horne ◽  
M.J. Hedley ◽  
J.A. Hanly ◽  
V.O. Snow
Keyword(s):  
Dairy Farming ◽  
Drainage Water ◽  
Nutrient Concentrations ◽  
Dairy Effluent ◽  
Total N ◽  
Artificial Drainage ◽  
Effluent Irrigation ◽  
Farm Dairy Effluent ◽  
The Impact ◽  
Total P

While it is widely believed that intensive dairy farming is a major contributor to the increased nutrient loads in surface waters, there is little current research quantifying the magnitude of nutrient loss from dairy farms to waterways, particularly from artificial drainage. An experimental site has been established on a Pallic soil (Tokomaru silt loam) to measure the impacts of intensive dairying on the quality and quantity of drainage water exiting from an artificial drainage system. A key component of this study is the development and evaluation of a land-based treatment system for farm dairy effluent (deferred irrigation). The research site has eight replicated plots, each with an isolated mole and pipe drain network. All the plots are subjected to the farm's standard grazing management. Four of the plots receive fer tiliser according to the farm's fertiliser programme, while the other four plots receive applications of farm dairy effluent. Measurements of drainage flows during year one of this study showed that the average concentrations of total nitrogen (12.9 mg N/L) and total phosphorus (0.15 mg P/L) in drainage water for the winter of 2002 under standard dairy farming practices were all well above the levels necessary to prevent aquatic weed growth in fresh water bodies. Adherence to the scheduling criteria prescribed by the 'deferred irrigation' system prevented the direct loss of nutrients during irrigation of farm dairy effluent in the summer of 2001/2002. Summer applications of farm dairy effluent did not increase N loss in subsequent winter drainage. Effluent irrigation increased P loss during the subsequent winter drainage period by 0.52 kg total-P/ha (0.38 kg P/ha as DIP). However, this increase in total loss corresponds to less than 4% of the P (16 kg/ha) applied as effluent. Deferred irrigation proved to be a very successful tool for minimising nutrient losses from effluent irrigated areas in direct drainage of effluent at the time of irrigation and subsequent winter drainage. Dairy cattle grazing events also increased nutrient concentrations in drainage waters following grazing by approximately 5 mg total-N/L (nearly all in the nitrate form) and 0.1 mg total-P/L (nearly all in the DIP form). The effect of an application of urea in spring on nitrate-N concentrations in drainage water was minimal. Keywords: dairying, effluent irrigation, mole and pipe drainage, nitrogen, nutrient leaching phosphorus, water quality

LAND USE TYPES AND SOIL CHARACTERISTICTS: A CASE STUDY IN HUONG VINH COMMUNE, HUONG TRA TOWN, THUA THIEN HUE PROVINCE

2017 ◽  
Vol 126 (4B) ◽  
Author(s):  
Trần Thanh Đức
Keyword(s):  
Land Use ◽  
Sweet Potato ◽  
Soil Analysis ◽  
Soil Characteristics ◽  
Low Ph ◽  
Clay Loam ◽  
Total N ◽  
Land Use Types ◽  
Total P

This research carried out in Huong Vinh commune, Huong Tra town, Thua Thien Hue province aimed to identify types of land use and soil characteristics. Results showed that five crops are found in Huong Vinh commune including rice, peanut, sweet potato, cassava and vegetable. There are two major soil orders with four soil suborders classified by FAO in Huong Vinh commune including Fluvisols (Dystric Fluvisols<em>, </em>Gleyic Fluvisols and Cambic Fluvisols) and Arenosols (Haplic Arenosols). The results from soil analysis showed that three soil suborders including Dystric Fluvisols<em>, </em>Gleyic Fluvisols and Cambic Fluvisols belonging to Fluvisols were clay loam in texture, low pH, low in OC, total N, total P<sub>2</sub>O<sub>5</sub> and total K<sub>2</sub>O. Meanwhile, the Haplic Arenosols was loamy sand in texture, poor capacity to hold OC, total N, total P<sub>2</sub>O<sub>5</sub> and total K<sub>2</sub>O

scholarly journals Genetic variation of seed phosphorus concentration in winter oilseed rape and development of a NIRS calibration

Euphytica ◽  
2021 ◽  
Vol 217 (4) ◽  
Author(s):  
Jakob Eifler ◽  
Jürgen Enno Wick ◽  
Bernd Steingrobe ◽  
Christian Möllers
Keyword(s):  
Genetic Variation ◽  
Field Experiments ◽  
Seed Quality ◽  
Rapeseed Meal ◽  
Quality Analysis ◽  
Phosphorus Concentration ◽  
Genotypic Differences ◽  
Organic P ◽  
P Concentration ◽  
Total P

AbstractPhytic acid is the major organic phosphorus storage compound in rapeseed. Following oil extraction, the defatted meal is used in feed mixtures for livestock. However, monogastric pigs and chickens can only poorly metabolize phytate. Hence, their excrements are rich in phosphorus (P), which when applied as manure may lead to eutrophication of surface waters. The aim of the present study was to analyze the genetic variation for total and organic P concentration (i.e. mainly phytate) in rapeseed and to compare the results with soybean. Two sets of rapeseed material were tested in field experiments in different environments with varying soil P levels and harvested seeds were used for seed quality analysis. Results revealed significant genotypic differences in total seed P concentration, which ranged from 0.47 to 0.94%. Depending on the experiment, the heritability for total P concentration ranged from 52 to 93%. The organic P portion of total P concentration was above 90% for current rapeseed hybrids. In both sets, there was a significant positive correlation between seed protein and P concentration. A NIRS calibration for total P concentration in intact seeds showed in cross validation a standard error of 0.05% and a coefficient of determination of R2 = 0.83. Total P concentration of soybean seeds and meal was between 0.55 and 0.65%, and around 1.1% for rapeseed meal. Rapeseed meal had a twofold higher ratio of total P to nitrogen concentration as compared to soybean which could be considered adverse when the meal is used for feeding livestock.

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