Prediction of Emergent and Floating-Leaved Macrophyte Cover in Central Swedish Lakes

1986 ◽  
Vol 43 (12) ◽  
pp. 2519-2523 ◽  
Author(s):  
Val H. Smith ◽  
Maud Wasllsten
Keyword(s):  
Regression Analysis ◽  
Total Nitrogen ◽  
Nitrogen Concentration ◽  
Percent Cover ◽  
Lake Surface ◽  
Emergent Macrophytes ◽  
Factors Influencing ◽  
Total Nitrogen Concentration ◽  
Lake Surface Area ◽  
Macrophyte Cover

From multiple regression analysis of data from Central Swedish lakes, we suggest that the peak areal cover (hectares) of emergent vegetation is predictable from lake surface area, mean depth, and annual mean total nitrogen concentration in the lake water. The data also suggest that the percent cover of emergent macrophytes is predictable from mean depth and total nitrogen. However, the factors influencing floating-leaved macrophyte cover are not as clear.

Factors Influencing the Calibration of near Infrared Reflectometry Applied to the Assessment of Total Nitrogen in Potato. II. Operator, Moisture and Maturity Class

1995 ◽  
Vol 3 (3) ◽  
pp. 167-174 ◽  
Author(s):  
Mark W. Young ◽  
Donald K.L. MacKerron ◽  
Howard V. Davies
Keyword(s):  
Field Experiment ◽  
Spectral Data ◽  
Total Nitrogen ◽  
Near Infrared ◽  
Nitrogen Concentration ◽  
Moisture Contents ◽  
Factors Influencing ◽  
Maturity Class ◽  
The One ◽  
Low Nitrogen

Oven dried samples of leaf stem and tuber material taken from a nitrogen field experiment were analysed by Dumas combustion when fresh and by near infrared (NIR) then, and in the next two years, by a number of operators who made estimates of nitrogen concentration, [N]NIR, with differing degrees of error. The errors differed between years in the case of the one operator who made estimates in two years. Leaf, stem and tuber material of high and low nitrogen concentration were treated to produce samples at various moisture contents. These samples were scanned by NIR and the spectral data were examined. Higher moisture was found to decrease the reflectance at all the wavelengths used and would, therefore, introduce error into [N]NIR estimates. The NIR calibration used was found to be applicable to cultivars in a range of maturity classes. Several recommendations are made that will help to minimise the error introduced into [N]NIR estimates from various sources.

Total nitrogen concentration in leaves of potatoes (Solanum tuberosumL.) as an index of nutritional status

1976 ◽  
Vol 87 (2) ◽  
pp. 293-296 ◽  
Author(s):  
A. Gupta ◽  
M. C. Saxena
Keyword(s):  
Total Nitrogen ◽  
Tuber Yield ◽  
Critical Concentration ◽  
Nitrogen Concentration ◽  
Curvilinear Relationship ◽  
N Application ◽  
Total N ◽  
Potato Plants ◽  
N Concentration ◽  
Total Nitrogen Concentration

SummaryLeaf samples were collected, at weekly intervals, throughout the growing season, from potato (Solanum tuberosumL.) plants supplied with varying amounts of nitrogen (0, 60, 120, 180 and 240 kg N/ha) and analysed for total N. Application of nitrogen increased the N concentration in the green leaves at all stages of growth. There was a significant curvilinear relationship between the final tuber yield and the total N concentration in the leaves at 48–90 days after planting in 1968–9 and at 79–107 days after planting in 1969–70. The N concentration at 70–90 days after planting was consistently related to the final tuber yield in both years. Thus this period was ideal for assessing the nitrogen status of potato plants. The critical concentration of total nitrogen generally decreased with advance in age. It ranged from 4·65% at 76 days to 3·30% at 90 days during 1968–9, whereas in 1969–70 it ranged from 4·20% at 79 days to 3·80% at 93 days. During the period from 83 to 86 days the critical percentage was around 3·6% in both the years.

Impact of chloride on nitrate absorption and accumulation by broccoli (Brassica oleracea var. italica)

1996 ◽  
Vol 76 (2) ◽  
pp. 367-377 ◽  
Author(s):  
Liangxue Liu ◽  
Barry J. Shelp
Keyword(s):  
Brassica Oleracea ◽  
Total Nitrogen ◽  
Nitrogen Concentration ◽  
Xylem Sap ◽  
Phloem Exudate ◽  
Nitrate Accumulation ◽  
Total Nitrogen Concentration ◽  
Nitrate Absorption ◽  
Final Yield ◽  
Chloride Treatment

In the present study, we tested the hypothesis that continuous chloride treatment decreases nitrate absorption and accumulation by broccoli (Brassica oleracea var. italica) plants. In a field experiment, both fresh and dry weights of shoot and inflorescence increased linearly with increasing nitrogen applied (70–130 kg ha−1). Chloride application (0–450 kg ha−1) did not significantly affect the final yield. In a greenhouse experiment in which the plants were grown in soilless culture and supplied with 10–18 mmol L−1 nitrate, only the fresh weights of shoot and inflorescence decreased linearly with increasing chloride application (0–45 mmol L−1). In both experiments, increasing chloride application slightly decreased the concentrations of nitrate nitrogen and total nitrogen in xylem sap, and increased the chloride concentrations of both xylem sap and phloem exudate and the total-nitrogen concentration of phloem exudate. The shoot-nitrate contents increased with increasing nitrogen application and decreased with increasing chloride application, whereas the shoot-chloride contents increased with increasing chloride application and decreased with increasing nitrate application. The total-nitrogen contents of the shoot were not affected by chloride application. These data are interpreted to suggest that nitrate absorption was not inhibited by the presence of chloride in the growing medium and that the decrease in nitrate accumulation of the shoot resulted from the stimulation of organic-nitrogen formation from absorbed nitrate. Key words: Antagonism, broccoli, chloride, interaction, nitrate

Influence of the Initial Nitrogen Concentration on Eliminating Nitrogen Load of Europhia Sediment Capping with Active Barrier System (ABS)

2011 ◽  
Vol 374-377 ◽  
pp. 498-503
Author(s):  
Jin Lan Xu ◽  
Lei Wang ◽  
Jun Chen Kang ◽  
Ting Lin Huang ◽  
Yu Hua Dong
Keyword(s):  
Total Nitrogen ◽  
Nitrate Nitrogen ◽  
Nitrogen Concentration ◽  
Ammonia Nitrogen ◽  
Overlying Water ◽  
Sediment Capping ◽  
Time Treatment ◽  
Total Nitrogen Concentration ◽  
Long Time ◽  
Active Barrier

Abstract: Active barrier system (ABS) capping zeolite with large surface area and strong adsorption ability is an effective way to control eutrophication of lake since it can remove ammonia in the lake released by sediment. Influence of the initial nitrogen concentration on eliminating nitrogen load of europhia sediment capping with active barrier system (ABS) were studied through an investigation of the repairment results of serious pollution period (total nitrogen concentration up to 25.33 mg/L), moderate pollution period (14.39 mg/L) and the slight pollution period (3.47 mg/L) of the ancient Canal of Yangzhou. The results showed that: (1) zeolite F1 inhibition effect is stronger than zeolite F2. More TN were removed as the initial TN concentration increased and longer rapid inhibit period were presented with the increased initial TN concentration. (2) The ammonia nitrogen in sediment could be rapidly released into the overlying water, and with lower initial TN concentration in source water, more ammonia would be released from the sediment. Long time treatment was necessary to inhibit the release of ammonia completely if the water showed a high initial TN concentration. (3) After covering zeolite, the total nitrogen in the overlying water were removed mainly through nitrification and denitrification. At the initial TN concentration of 3.47 mg/L, 14.39 mg/L, 25.88 mg/L, 61%, 45% and 52% of TN were removed by the conversion of ammonia to nitrogen gas, however, others left in water as nitrate nitrogen and nitrite residues, and 90% was nitrate nitrogen.

scholarly journals LEAF TOTAL NITROGEN CONCENTRATION AS AN INDICATOR OF NITROGEN STATUS FOR PLANTLETS AND YOUNG PLANTS OF EUCALYPTUS CLONES

2015 ◽  
Vol 39 (4) ◽  
pp. 1127-1140 ◽  
Author(s):  
Eric Victor de Oliveira Ferreira ◽  
Roberto Ferreira Novais ◽  
Bruna Maximiano Médice ◽  
Nairam Félix de Barros ◽  
Ivo Ribeiro Silva
Keyword(s):  
Total Nitrogen ◽  
Block Design ◽  
Nitrogen Concentration ◽  
Soil N ◽  
Total N ◽  
Chlorophyll Meter ◽  
N Concentration ◽  
Total Nitrogen Concentration ◽  
N Status ◽  
Leaf N

The use of leaf total nitrogen concentration as an indicator for nutritional diagnosis has some limitations. The objective of this study was to determine the reliability of total N concentration as an indicator of N status for eucalyptus clones, and to compare it with alternative indicators. A greenhouse experiment was carried out in a randomized complete block design in a 2 × 6 factorial arrangement with plantlets of two eucalyptus clones (140 days old) and six levels of N in the nutrient solution. In addition, a field experiment was carried out in a completely randomized design in a 2 × 2 × 2 × 3 factorial arrangement, consisting of two seasons, two regions, two young clones (approximately two years old), and three positions of crown leaf sampling. The field areas (regions) had contrasting soil physical and chemical properties, and their soil contents for total N, NH+4-N, and NO−3-N were determined in five soil layers, up to a depth of 1.0 m. We evaluated the following indicators of plant N status in roots and leaves: contents of total N, NH+4-N, NO−3-N, and chlorophyll; N/P ratio; and chlorophyll meter readings on the leaves. Ammonium (root) and NO−3-N (root and leaf) efficiently predicted N requirements for eucalyptus plantlets in the greenhouse. Similarly, leaf N/P, chlorophyll values, and chlorophyll meter readings provided good results in the greenhouse. However, leaf N/P did not reflect the soil N status, and the use of the chlorophyll meter could not be generalized for different genotypes. Leaf total N concentration is not an ideal indicator, but it and the chlorophyll levels best represent the soil N status for young eucalyptus clones under field conditions.

EFFECT OF UREA AND AMMONIUM NITRATE ON YIELDS AND NITROGEN CONCENTRATION OF TIMOTHY AND BROMEGRASS AND LOSS OF AMMONIA FROM UREA SURFACE APPLICATIONS

1987 ◽  
Vol 67 (1) ◽  
pp. 185-192 ◽  
Author(s):  
H. T. KUNELIUS ◽  
J. A. MACLEOD ◽  
K. B. MCRAE
Keyword(s):  
Ammonium Nitrate ◽  
Total Nitrogen ◽  
Dry Matter ◽  
Field Experiments ◽  
Nitrogen Concentration ◽  
Secondary Growth ◽  
Nitrogen Sources ◽  
Primary Growth ◽  
Total Nitrogen Concentration ◽  
Harvest Year

Urea and ammonium nitrate were applied at 30, 60, 90 and 120 kg N ha−1 in spring and after cutting the primary growth of timothy and bromegrass in three field experiments. Dry matter yields of timothy and bromegrass and total nitrogen concentration of tissue and nitrogen yields of timothy were determined. Loss of nitrogen as ammonia was monitored on microplots between the end of May and early July. Primary growth yields were usually similar for ammonium nitrate and urea but in the secondary growth timothy fertilized with ammonium nitrate outyielded timothy fertilized with urea in four out of six harvest years. Dry matter response to applied nitrogen was usually curvilinear in primary growth but linear in secondary growth over the nitrogen rates studied. Total nitrogen concentration in primary and secondary growths of timothy increased linearly with nitrogen rate during the initial 2–3 yr; ammonium nitrate and urea were equally effective in all but one harvest year. Total nitrogen production of timothy also increased linearly over the range of 30–120 kg N ha−1, while ammonium nitrate outyielded urea-fertilized timothy during one season in primary and two seasons out of four in secondary growth. Nitrogen losses increased from spring to summer, in general, with 68–75% of the variation explained by air temperature. Urea and ammonium nitrate were considered equivalent nitrogen sources for the primary growth of timothy but urea was less efficient in the secondary growth under summer conditions.Key words: Urea, ammonium nitrate, timothy, bromegrass, ammonia losses

Spectrometric prediction of secondary metabolites and nitrogen in fresh Eucalyptus foliage: towards remote sensing of the nutritional quality of foliage for leaf-eating marsupials

2002 ◽  
Vol 50 (6) ◽  
pp. 761 ◽  
Author(s):  
M. J. H. Ebbers ◽  
I. R. Wallis ◽  
S. Dury ◽  
R. Floyd ◽  
W. J. Foley
Keyword(s):  
Total Nitrogen ◽  
Near Infrared ◽  
Leaf Surface ◽  
Nitrogen Concentration ◽  
Near Infrared Reflectance ◽  
Ecological Attributes ◽  
Total Nitrogen Concentration ◽  
Volatile Terpene ◽  
Water Absorbance

Near-infrared reflectance spectroscopy provides an excellent means of assessing the chemical composition of Eucalyptus foliage but the standard methods of drying and grinding the samples limit the speed at which spectra can be collected and thus are unsuitable for measurements in the field. We investigated whether reliable spectra could be collected from whole fresh and dry leaves of E. melliodora and E. globulus and whether we could predict the concentration of total nitrogen, the volatile terpene, 1,8 cineole and the phenolic antifeedant compound, sideroxylonal A, from these spectra. Water absorbance peaks did not obscure the absorption spectrum of 1,8 cineole and so cineole concentration was readily predicted from spectra of whole, fresh E. melliodora leaves. Similarly, both total nitrogen and sideroxylonal A could be predicted from spectra of fresh leaf in E. melliodora even though water absorption obscured some spectral features. The predictions of cineole and total nitrogen concentration in E. globulus were not as good as those in E. melliodora, possibly due to interference from waxes on the leaf surface of E. globulus juvenile foliage. Overall, these results suggest that certain important ecological attributes of Eucalyptus foliage can be predicted from spectra of whole fresh leaves. Thus, it is feasible to investigate the collection of spectra by portable or airborne spectrophotometry.

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