Recovery of 15N-labelled fertilizers applied to bromegrass on a Thin Black Chernozem soil

1995 ◽  
Vol 75 (4) ◽  
pp. 539-542 ◽  
Author(s):  
S. S. Malhi ◽  
M. Nyborg ◽  
J. T. Harapiak
Keyword(s):  
Ammonium Nitrate ◽  
Early Spring ◽  
Late Spring ◽  
N Recovery ◽  
Chernozem Soil ◽  
Band Placement ◽  
Late Autumn ◽  
Time Of Application ◽  
Broadcast Application ◽  
Early Autumn

The availability of N fertilizers on established grass stands is a function of such processes as immobilization, gaseous loss, leaching and position of applied N. A field experiment was conducted on a Thin Black Chernozem soil at Crossfield, Alberta to determine the effect of source, time and method of application on the recovery of 15N-labelled fertilizers applied to smooth bromegrass (Bromus inermis Leyss.). The treatments included two sources of N [urea and ammonium nitrate (AN)], four application times (early autumn, late autumn, early spring and late spring) and two methods of placement (surface-broadcast and subsurface banding). In most cases the 15N recovery in soil did not differ much between urea and AN. However, when urea was surface-broadcast, there was, on average, 10.2% less 15N recovery in plants than AN. The N recovery for late spring > early spring > late autumn = early autumn. When urea was banded 4 cm deep into the soil, N recovery in plants increased significantly compared with its surface-broadcast application. However, this was not observed when the source of N was AN. Banding generally increased the amount of immobilized N present in the soil and N recovery. We concluded that the N recovery in plants and in plants plus soil was less for urea than for AN and was less with autumn broadcast N application than with spring broadcast application. Key words: Ammonium nitrate, band placement, bromegrass, recovery of N, surface-broadcast, time of application, urea

Ecology of lice on sheep. VII. Population dynamics of Damalinia ovis (Schrank)

1969 ◽  
Vol 17 (2) ◽  
pp. 179 ◽  
Author(s):  
MD Murray ◽  
G Gordon
Keyword(s):  
Population Dynamics ◽  
Matrix Model ◽  
Direct Relationship ◽  
Early Spring ◽  
Late Spring ◽  
Winter Period ◽  
Late Autumn ◽  
Early Autumn ◽  
Deterministic Matrix

The numbers of D. ovis decline in the spring, remain low during the summer, and increase during the winter. A density of two lice per square inch is necessary in the autumn if numbers are to increase during the winter to 200 per square inch, the density found on heavily infested sheep in the early spring. The time needed for this increase has been calculated using the deterministic matrix model ofpopulation increase described by Leslie (1945), and 4-5 months are required when there is only a small mortality. Thus, when the favourable winter period lasts only 3 months, the increase in louse numbers may be insufficient to sustain the losses which occur in late spring, summer, and early autumn. The factors responsible for these losses determine the density of the louse population at the commencement of winter. Should the winter period last c. 6 months there is usually a direct relationship between the number of lice on a sheep in the late autumn and in the following spring. However, should winter last 9 months it is suggested that other factors become increasingly significant, and determine the eventual size of the louse population.

TIME OF APPLICATION AND SOURCE OF NITROGEN FERTILIZER ON YIELD, QUALITY, NITROGEN RECOVERY, AND NET RETURNS FOR DRYLAND FORAGE GRASSES

1986 ◽  
Vol 66 (4) ◽  
pp. 915-931 ◽  
Author(s):  
C. A. CAMPBELL ◽  
A. J. LEYSHON ◽  
R. P. ZENTNER ◽  
H. UKRAINETZ
Keyword(s):  
Ammonium Nitrate ◽  
Early Spring ◽  
N Fertilizer ◽  
Grass Species ◽  
N Recovery ◽  
Brown Soil ◽  
Time Of Application ◽  
Net Returns ◽  
Soil Zone ◽  
Forage Yields

Studies were conducted in Saskatchewan for 4 yr at Swift Current (Brown soil zone) and 3 yr at Scott (Dark Brown soil zone) to assess the effect of time of application and source of N fertilizer on grass forage yields and N and P content, fertilizer N recovery and net returns. A single rate of N, 50 kg ha−1 was applied to established forage stands at three dates during the late fall to early winter period and one or two dates during the early spring period. Six grass species were grown at Swift Current and one at Scott. At Swift Current there were significant differences in dry matter yields between grass species but no species × fertilizer interactions. Fertilizer applied in April generally gave the highest forage yields and N concentration, N recovery, and net returns, but sometimes October and/or November applications provided as good or better results. At Swift Current relative yields (averaged over grass species and source of N) for the different application dates were: April, 158; late October, 154; late November, 145; and late December, 137; with the unfertilized control given a value of 100. At Scott, a similar rating of yields gave: mid-April, 225; mid-October, 219; mid-November, 216; mid-December, 213; and mid-March, 192. Nitrogen concentration in forages averaged 2.06% at Swift Current and 1.53% at Scott, and was mainly affected (increased) by the April fertilizer application date. Yields were 11–13% greater when ammonium nitrate was used compared to when urea was used. Because the N was broadcast and yields were small, recoveries of N by the crop were low, variable due to weather, and averaged 21% at both sites. In most years N fertilizer increased yields, but net returns varied depending on the occurrence of early spring precipitation and on whether the forage was sold for hay or fed on the farm. Fertilization was profitable in the wetter years, but in dry years money was lost irrespective of the N source or site. Net returns favored the ammonium nitrate source of N.Key words: Grass species, grass yield, urea, ammonium nitrate, net returns

Cycles of reproduction and condition in Tasmanian blue mussels, Mytilus edulis planulatus

1984 ◽  
Vol 35 (3) ◽  
pp. 307 ◽  
Author(s):  
TG Dix ◽  
A Ferguson
Keyword(s):  
Mytilus Edulis ◽  
Early Spring ◽  
Late Winter ◽  
Reproductive Condition ◽  
Late Autumn ◽  
Blue Mussels ◽  
Early Autumn ◽  
Condition Indices ◽  
One Year ◽  
Autumn And Winter

Major spawning by M. e. planulatus occurred in the late winter or early spring at Hinders Reef, Margate and Birchs Bay in 1980 and 1981. Spawning occurred also over the summer and early autumn although a major spawning was indicated during this period at only one site in one year. At the two sites where temperatures were recorded, the major spring spawning occurred at about or just above 10�C. Gonads built up reproductive condition during late autumn and winter at all sites in 1980 and 1981. Condition indices were highest at these times and fell when spring spawning occurred.

scholarly journals Measurement report: characteristics of clear-day convective boundary layer and associated entrainment zone as observed by a ground-based polarization lidar over Wuhan (30.5° N, 114.4° E)

2021 ◽  
Vol 21 (4) ◽  
pp. 2981-2998
Author(s):  
Fuchao Liu ◽  
Fan Yi ◽  
Zhenping Yin ◽  
Yunpeng Zhang ◽  
Yun He ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Convective Boundary Layer ◽  
Growth Stage ◽  
Late Spring ◽  
Atmospheric Measurements ◽  
Convective Boundary ◽  
Late Autumn ◽  
Early Autumn ◽  
Entrainment Zone ◽  
Aerosol Backscatter

Abstract. Knowledge of the convective boundary layer (CBL) and associated entrainment zone (EZ) is important for understanding land–atmosphere interactions and assessing the living conditions in the biosphere. A tilted 532 nm polarization lidar (30∘ off zenith) has been used for the routine atmospheric measurements with 10 s time and 6.5 m height resolution over Wuhan (30.5∘ N, 114.4∘ E). From lidar-retrieved aerosol backscatter, instantaneous atmospheric boundary layer (ABL) depths are obtained using the logarithm gradient method and Harr wavelet transform method, while hourly mean ABL depths are obtained using the variance method. A new approach utilizing the full width at half maximum of the variance profile of aerosol backscatter ratio fluctuations is proposed to determine the entrainment zone thickness (EZT). Four typical clear-day observational cases in different seasons are presented. The CBL evolution is described and studied in four developing stages (formation, growth, quasi-stationary and decay); the instantaneous CBL depths exhibited different fluctuation magnitudes in the four stages and fluctuations at the growth stage were generally larger. The EZT is investigated for the same statistical time interval of 09:00–19:00 LT. It is found that the winter and late autumn cases had an overall smaller mean (mean) and standard deviation (SD) of EZT data compared to those of the late spring and early autumn cases. This statistical conclusion was also true for each of the four developing stages. In addition, compared to those of the late spring and early autumn cases, the winter and late autumn cases had larger percentages of EZT falling into the subranges of 0–50 m but smaller percentages of EZT falling into the subranges of > 150 m. It seems that both the EZT statistics (mean and SD) and percentage of larger EZT values provide measures of entrainment intensity. Common statistical characteristics also existed. All four cases showed moderate variations of the mean of the EZT from stage to stage. The growth stage always had the largest mean and SD of the EZT and the quasi-stationary stage usually the smallest SD of the EZT. For all four stages, most EZT values fell into the 50–150 m subrange; the overall percentage of the EZT falling into the 50–150 m subrange between 09:00 and 19:00 LT was > 67 % for all four cases. We believe that the lidar-derived characteristics of the clear-day CBL and associated EZ can contribute to improving our understanding of the structures and variations of the CBL as well as providing a quantitatively observational basis for EZ parameterization in numerical models.

Seasonal distribution of loline alkaloid concentration in meadow fescue infected with Neotyphodium uncinatum

2011 ◽  
Vol 62 (7) ◽  
pp. 603 ◽  
Author(s):  
Brian Patchett ◽  
Ravi Gooneratne ◽  
Lester Fletcher ◽  
Bruce Chapman
Keyword(s):  
Late Summer ◽  
Seasonal Distribution ◽  
Late Spring ◽  
Selected Lines ◽  
Meadow Fescue ◽  
Late Autumn ◽  
Early Autumn ◽  
Harvest Dates ◽  
Loline Alkaloids ◽  
First Time

Loline alkaloids are present in meadow fescue containing the endophyte (Neotyphodium uncinatum Gams, Petrini and Schmidt) (Clavicipitacae). Root, crown and shoot loline alkaloid concentrations in 10 selected lines from meadow fescue ecotypes are reported for the first time, from a Canterbury farm during 2004–05. The concentrations of four loline alkaloid derivatives, N-formyl loline (NFL), N-acetyl loline (NAL), N-acetyl norloline (NANL) and N-methyl loline (NML), in these lines (each line represented by one genotype) were determined at four harvest dates during late spring, late summer, and early and late autumn. There were marked differences in loline alkaloid concentration between lines and seasons. Maximum shoot loline concentration was recorded in summer (up to 2860 µg/g in Fp408). Root loline alkaloid concentration was substantially higher in late autumn (up to 790 µg/g in Fp408) and the shoot concentration correspondingly lower than in spring, summer and early autumn suggesting loline alkaloid transportation from shoots to roots. In the lines tested at each of the four harvest dates in spring, summer, and autumn, the root, crown, and shoot alkaloid concentration with minor exceptions was NFL > NAL > NANL > NML.

Time of application and chemical form of potassium, phosphorus, magnesium and sodium fertilizers and effects on the growth, yield and quality of sugarbeet (Beta vulgaris)

1994 ◽  
Vol 123 (1) ◽  
pp. 61-70 ◽  
Author(s):  
M. F. Allison ◽  
K. W. Jaggard ◽  
M. J. Armstrong
Keyword(s):  
Field Experiments ◽  
Growth Yield ◽  
Early Spring ◽  
Late Spring ◽  
Low Fertility ◽  
Processing Quality ◽  
Time Of Application ◽  
Economic Significance ◽  
The Uk

SummarySummary Between 1985 and 1988, 14 field experiments at different sites in the UK assessed the effect of applying P, K, Na and Mg in autumn, early spring, late spring or as a split application in both autumn and late spring on the growth, yield and processing quality of sugarbeet. Supplementary experiments compared Kaynitro and Chilean nitrate of soda. None of the treatments had any effect on plant population densities, and any differences in sugar yield could be explained by the leaching of Na. The effects on processing quality were inconsistent and unlikely to be of agronomic or economic significance. Generally, Kaynitro and Chilean nitrate of soda performed no better than the other fertilizers so it is unlikely that their extra cost would be justified. Apart from Na, the timing of nutrient application appeared to be unimportant, even on soils of low fertility. However, Na, being very mobile, was best applied in spring.

STUDIES OF THE TOMATO IN RELATION TO ITS STORAGE: I. A SURVEY OF THE EFFECT OF MATURITY AND SEASON UPON THE RESPIRATION OF GREENHOUSE FRUITS AT 12.5 °C.

1938 ◽  
Vol 16c (2) ◽  
pp. 65-83 ◽  
Author(s):  
E. J. M. Walford
Keyword(s):  
Low Temperature ◽  
Respiration Rate ◽  
Stable State ◽  
Early Spring ◽  
Late Spring ◽  
Red Pigment ◽  
External Appearance ◽  
Late Autumn ◽  
Different Seasons

Tomatoes were grown in the greenhouse at different seasons of the year, individual fruits were picked at various stages of maturity and continuous records of their respiration obtained at 12.5 °C. It was found that the fruits of the late spring and summer went through the customary series of extensive changes in respiration rate as they ripened at the low temperature, and exhibited the lack of durability normal to this fruit. In contrast to this, the fruits of the late autumn, winter and early spring, if picked before the external appearance of red pigment, passed into a stable state in which ripening proceeded with but little change in respiration rate and with greatly enhanced duration of life at 12.5 °C.

Effect of nitrogen source, placement and time of application on winter wheat production in Saskatchewan

1991 ◽  
Vol 71 (2) ◽  
pp. 177-187 ◽  
Author(s):  
C. A. Campbell ◽  
F. Selles ◽  
W. Nuttall ◽  
T. Wright ◽  
H. Ukrainetz
Keyword(s):  
Winter Wheat ◽  
Ammonium Nitrate ◽  
Protein Concentration ◽  
Triticum Aestivum L ◽  
Early Spring ◽  
The Other ◽  
Grain Protein ◽  
Grain Protein Concentration ◽  
Brown Soil ◽  
Time Of Application

Saskatchewan producers growing primarily spring-seeded cereals may be interested in diversifying their cropping alternatives. Winter wheat (Triticum aestivum L.) could provide one possible option, but its management could cause conflict with the busy fall and early spring activities for spring-seeded crops. A study was conducted at five sites (Swift Current, 4 yr; Melfort, 4 yr; and Scott, Lashburn, and Loon Lake, 1 yr each) in four soil zones (Brown, Dark Brown, and Black Chernozems and Gray Luvisol). The effect of time of application of N (seeding to early spring), source of N (ammonium nitrate vs. urea), and method of application (broadcast, midrow band, and seed-placed) on yield and grain protein concentration were investigated. The results varied with site and year (weather). Time of N application only influenced yields at Swift Current (Brown soil) where application on cool unfrozen soil in mid-October was as good as application in early spring and better than at other times, and application onto frozen, snow-covered soil in December was least effective. At Swift Current and Melfort, grain protein concentration did not respond to time of application; however, at Scott, Lashburn and Loon Lake, protein was highest for spring-applied N, followed by mid-October, and lowest when N was applied on frozen snow-covered soil. The effect of N source rarely affected grain yield or protein and was dependent on site and method of placement. The dangers of seed-placing N, especially urea, on overwinter survival and yields were evident in 2 yr at Swift Current. There was rarely any difference in yield or grain protein concentration when N was banded or broadcast at seeding time. Taking into account convenience of operation, the most opportune time for Saskatchewan producers involved in growing both spring and winter wheat to apply N would be mid-October in the Brown soil zone. In the other soil zones, early spring would be best. Broadcasting the N was the most appropriate method of application at all sites. Urea would be chosen over ammonium nitrate because there was little advantage of one source over the other and urea is generally cheaper. Key words: Urea, ammonium nitrate, protein, grain yields, plant population

scholarly journals Do applications of systemic herbicides when green fruit are present prevent seed production or viability of Alliaria petiolata (garlic mustard)?

2021 ◽  
pp. 1-17
Author(s):  
Leo Roth ◽  
José Luiz C. S. Dias ◽  
Christopher Evans ◽  
Kevin Rohling ◽  
Mark Renz
Keyword(s):  
Seed Production ◽  
Seed Viability ◽  
Early Spring ◽  
Alliaria Petiolata ◽  
Late Spring ◽  
Garlic Mustard ◽  
Viable Seed ◽  
Application Timing ◽  
Control Seed ◽  
Second Year

Garlic mustard [Alliaria petiolata (M. Bieb.) Cavara & Grande] is a biennial invasive plant commonly found in the northeastern and midwestern United States. Although it is not recommended to apply herbicides after flowering, land managers frequently desire to conduct management during this timing. We applied glyphosate and triclopyr (3% v/v and 1% v/v using 31.8% and 39.8% acid equivalent formulations, respectively) postemergence to established, second-year A. petiolata populations at three locations when petals were dehiscing, and evaluated control, seed production and seed viability. Postemergence glyphosate applications at this timing provided 100% control of A. petiolata by 4 weeks after treatment at all locations whereas triclopyr efficacy was variable, providing 38-62% control. Seed production was only reduced at one location, with similar results regardless of treatment. Percent seed viability was also reduced, and when combined with reductions in seed production, we found a 71-99% reduction in number of viable seed produced plant-1 regardless of treatment. While applications did not eliminate viable seed production, our findings indicate that glyphosate and triclopyr applied while petals were dehiscing is a viable alternative to cutting or hand-pulling at this timing as it substantially decreased viable A. petiolata seed production. Management Implications Postemergence glyphosate and triclopyr applications in the early spring to rosettes are standard treatments used to manage A. petiolata. However, weather and other priorities limit the window for management, forcing field practitioners to utilize more labor-intensive methods such as hand-pulling. It is not known how late in the development of A. petiolata these herbicides can be applied to prevent viable seed production. Since prevention of soil seedbank replenishment is a key management factor for effective long-term control of biennial invasive species, we hypothesized late spring foliar herbicide applications to second year A. petiolata plants when flower petals were dehiscing could be an effective management tool if seed production or viability is eliminated. Our study indicated that glyphosate applications at this timing provided 100% control of A. petiolata plants by 4 weeks after treatment at all locations, whereas triclopyr efficacy was inconsistent. Although both glyphosate and triclopyr decreased viable seed production to nearly zero at one of our three study locations, the same treatments produced significant amounts of viable seed at the other two locations. Our findings suggest late spring glyphosate and triclopyr applications should not be recommended over early spring applications to rosettes for A. petiolata management, as our late spring application timing did not prevent viable seed production, and may require multiple years of implementation to eradicate populations. Nonetheless, this application timing holds value in areas devoid of desirable understory vegetation compared to no management practices or mechanical management options including hand-pulling when fruit are present, as overall viable seed production was reduced to similar levels as these treatments.

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