The Influence of Seasonal Variations On the Vertical Distribution of Meloidogyne Javanica in Sandy Soils

Nematologica ◽  
1966 ◽  
Vol 12 (2) ◽  
pp. 297-301 ◽  
Author(s):  
H. Koen
Keyword(s):  
Vertical Distribution ◽  
Seasonal Variations ◽  
Sandy Soils ◽  
Meloidogyne Javanica ◽  
The Vertical Distribution

scholarly journals Effects of DCD addition to slurry on nitrate leaching in sandy soils

1995 ◽  
Vol 43 (2) ◽  
pp. 195-204 ◽  
Author(s):  
W.J. Corre ◽  
K.B. Zwart
Keyword(s):  
Vertical Distribution ◽  
Nitrate Leaching ◽  
Soil Layer ◽  
Nitrification Inhibitor ◽  
Sandy Soils ◽  
Mineral Nitrogen ◽  
Cattle Slurry ◽  
Time Of Application ◽  
One Year ◽  
The Vertical Distribution

The effects of the addition of the nitrification inhibitor dicyandiamide (DCD) to cattle slurry, applied in autumn to an arable sandy soil, were investigated in a three-year field experiment in the Netherlands. Treatments included application of slurry with DCD in November and December, application of slurry without DCD in November, December and January, and an untreated (slurry or DCD) control. Degradation of DCD, changes in mineral nitrogen in the soil, and leaching of nitrate and DCD were measured. Degradation of DCD in the topsoil was complete in May after application in the autumn before. However, at a depth of 90 cm, DCD was found three months after application. DCD remained present in leachate sampled at this depth for more than one year after application. Most probably it was then leached to the groundwater. Application of DCD considerably delayed nitrification. It had a large effect on the vertical distribution of mineral nitrogen in spring; more mineral nitrogen was found in the 0-40 cm soil layer and less in the 40-100 cm soil layer. However, neither time of application of the slurry nor addition of DCD had a significant effect on nitrate leaching.

scholarly journals Vertical distribution and aggregation patterns of krill (Crustacea: Euphausiacea) in the Bay of Biscay: interannual and seasonal variability

2019 ◽  
Vol 97 (7) ◽  
pp. 619-630 ◽  
Author(s):  
M. Peña ◽  
R. González-Quirós ◽  
I. Munuera-Fernández ◽  
F. González ◽  
S. Romero-Romero ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Vertical Migration ◽  
Seasonal Variations ◽  
Seasonal Variability ◽  
Shelf Area ◽  
Bay Of Biscay ◽  
Acoustic Data ◽  
Epipelagic Zone ◽  
Acoustic Recording ◽  
The Vertical Distribution

Studies of krill (Crustacea: Euphausiacea) in oceanic waters of the Bay of Biscay are scarce and restricted to the epipelagic zone, overlooking vertical dynamics such as diurnal vertical migration (DVM). There is a growing interest in acoustically evaluating the biomass of krill in this area, but this requires a good knowledge of its vertical dynamics and aggregation patterns. In this work we employed acoustic data and net samples from two consecutive annual surveys covering a wide off-shelf area of the Bay of Biscay (JUVENA surveys of 2013 and 2014) and four seasonal surveys covering slope and oceanic waters in the Cantabrian Sea (SCAPA surveys of 2015). Vertical dynamics of krill were analyzed in the frame of the environmental seascape. High interannual and seasonal variations in the vertical distribution and aggregation patterns (small swarms, dense aggregations, or loose layers) of krill were observed. The vertical distribution covaried with dissolved oxygen and salinity. According to our findings, the best season to acoustically evaluate krill in the Bay of Biscay is spring, with the bulk of the biomass located above 600 m depth. Moreover, extending the acoustic recording beyond the epipelagic zone is mandatory for any season.

scholarly journals THE REDOX POTENTIALS IN SMALL OLIGO AND MEROMICTIC LAKES

1970 ◽  
Vol 1 (1) ◽  
pp. 56-65 ◽  
Author(s):  
JOHANNES KJENSMO
Keyword(s):  
Vertical Distribution ◽  
Redox Potential ◽  
Deep Water ◽  
Lake Water ◽  
Seasonal Variations ◽  
Redox Potentials ◽  
Ecological Significance ◽  
Meromictic Lakes ◽  
The Subject ◽  
The Vertical Distribution

The redox potentials of lake water have been the subject of several investigations (Kusnetzow 1935, Pearsall & Mortimer 1939, Hutchinson, Deevey & Wollack 1939, Deevey 1941, Allgeier, Hafford & Juday 1941, Mortimer 1941-42). The ecological significance of the redox potentials is stressed in several of these works. The work of Mortimer (1941-42) also shows the importance of the seasonal variations in redox potentials for the liberation from the sediments of different important nutrients. At present very little is known about the redox potential of the deep water in meromictic lakes. Allgeier, Hafford & Juday (1941) recorded vertical distribution of redox potential in one meromictic lake, Lake Mary, Wisconsin. The redox potential of the monimolimnion of Lake Mary varied from Eh = 0.140 volts at 8 m to Eh = 0.075 volts at 20.5 m. Hutchinson (1957) assumes it probable that other, but by no means all, meromictic lakes will be found to show a similar phenomenon. In the present paper the vertical distribution of redox potential of the water of three meromictic and one oligomictic lake is described.

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