Occurrence and simulation of nitrification in two contrasting sugarcane soils from the Australian wet tropics

Soil Research ◽  
2006 ◽  
Vol 44 (1) ◽  
pp. 1 ◽  
Author(s):  
E. A. Meier ◽  
P. J. Thorburn ◽  
M. E. Probert
Keyword(s):  
Incubation Period ◽  
Tropical Soils ◽  
Ammonium Nitrogen ◽  
Mineral N ◽  
Factors Affecting ◽  
Laboratory Conditions ◽  
Complex Processes ◽  
Nitrate N ◽  
Subtropical Soils ◽  
Wet Tropics

The concentration of ammonium-nitrogen (NH4+-N) frequently exceeds that of nitrate-N (NO3−-N) in Australian wet tropical sugarcane soils. The amount of mineral N in soil is the net result of complex processes in the field, so the objective of this experiment was to investigate nitrification and ammonification in these soils under laboratory conditions. Aerobic and saturated incubations were performed for 1 week on 2 wet tropical soils. Net NO3−-N increased significantly in both soils during both types of incubation. A second series of aerobic incubations of these soils treated with NH4+-N and inoculated with subtropical nitrifying soils was conducted for 48 days. Nitrification in the wet tropical soils was not significantly affected by inoculation, and virtually all added N was nitrified during the incubation period. Mineral N behaviour of the 48-day incubations was captured with the APSIM-SoilN model. As nitrification proceeded under laboratory conditions and was able to be captured by the model, it was concluded that nitrification processes in the wet tropical soils studied were not different from those in the subtropical soils. Processes that remove NO3− from the soil, such as leaching and denitrification, may therefore be important factors affecting the proportions of NH4+-N and NO3−-N measured under field conditions.

scholarly journals Assessment of Mesotrione Leaching Applied Alone and Mixed in Seven Tropical Soils Columns under Laboratory Conditions

Agriculture ◽  
2017 ◽  
Vol 8 (1) ◽  
pp. 1 ◽  
Author(s):  
Kassio Mendes ◽  
Marcelo dos Reis ◽  
Kurt Spokas ◽  
Valdemar Tornisielo
Keyword(s):  
Tropical Soils ◽  
Laboratory Conditions

Gamete biology of the new world marsupial, the grey short-tailed opossum, Monodelphis domestica

1996 ◽  
Vol 8 (4) ◽  
pp. 605 ◽  
Author(s):  
HD Moore
Keyword(s):  
Animal Model ◽  
New World ◽  
Monodelphis Domestica ◽  
Sperm Maturation ◽  
Developmental Changes ◽  
Gamete Fusion ◽  
Laboratory Conditions ◽  
Complex Processes ◽  
Gamete Biology

Mammalian gametes undergo a series of functional and developmental changes that culminate in fertilization. In order to appreciate the necessity for such complex processes as sperm maturation, capacitation and the intimate sperm-egg interactions leading to gamete fusion, it is important to understand how gametes may have evolved. In this respect, marsupials are particularly relevant since they exhibit features reminiscent of both non-mammalian vertebrates and eutherian mammals. The grey short-tailed opossum, Monodelphis domestica, is a New World marsupial from Brazil. It breeds well under laboratory conditions and is an excellent animal model to investigate marsupial gamete biology. As in other American marsupials, the spermatozoa of the opossum form pairs in the epididymis. Here, a number of studies carried out in this laboratory, related to sperm maturation, capacitation and fertilization in M. domestica, are reviewed and the gamete biology in this species is compared with what is known in other marsupials and eutherian mammals.

Some local factors affecting iridic lipid infiltration in hypercholesteremic rabbits

1959 ◽  
Vol 197 (4) ◽  
pp. 842-846 ◽  
Author(s):  
Meyer Friedman ◽  
Sanford O. Byers
Keyword(s):  
Cottonseed Oil ◽  
Aortic Tissue ◽  
Factors Affecting ◽  
Experimental Animals ◽  
Local Factors ◽  
Laboratory Conditions ◽  
Intermittent Exposure ◽  
Intense Light

The influence of various factors affecting the deposition of lipid and cholesterol in the iris of rabbits fed cholesterol and cottonseed oil was studied. It was observéd that this deposition could be increased by the intraocular implantation of either normal aortic tissue or polyethylene discs. In an additional study, it was found that intermittent exposure of the eyes of cholesterol-fed rabbits to intense light also provoked an earlier and more intense iris deposition of lipid and cholesterol than was observed in the eyes of similarly fed rabbits kept either in absolute darkness or under ordinary laboratory conditions. It was postulated that the factor responsible for the greater iridic deposition observed in all these experimental animals was the iridic vasodilatation effected by these experimental measures.

The Submerged Biofilm Process as a Pre-Treatment for Polluted Raw Water for Tap Water Supply

1990 ◽  
Vol 22 (1-2) ◽  
pp. 137-148 ◽  
Author(s):  
M. Takasaki ◽  
H. Kim ◽  
A. Sato ◽  
M. Okada ◽  
R. Sudo
Keyword(s):  
Tap Water ◽  
Ammonium Nitrogen ◽  
Raw Water ◽  
Factors Affecting ◽  
Treatment Performance ◽  
N Concentration ◽  
Pilot Plant Scale ◽  
Pre Treatment ◽  
Biofilm Process

The submerged biofilm process is a promising system for polluted raw water pre-treatment systems. General treatment performance and factors affecting treatment efficiency were investigated through pilot plant scale experiments using water from four different lakes. Regarding the quality of the raw waters, BOD was generally below 10 mg/l and the ammonium nitrogen (NH4-N) concentration was below 0.4 mg/l. The efficiency of removal of NH4-N was about 80% under complete mixing conditions and when the raw water quality did not fluctuate rapidly. Under the adverse conditions of the low water temperatures which occurred in winter and spring, the removal of NH4-N was 60 to 80%. The critical NH4-N concentration was observed to be approximately 0.01 to 0.02 mg/l, and a moderate decrease in E260 was also observed in the experiments. Overall treatment performance of the submerged biofilm process was superior in those systems with carriers which were not likely to become clogged.

Mechanism of Rubber Cracking

1946 ◽  
Vol 19 (2) ◽  
pp. 406-416 ◽  
Author(s):  
E. F. Powell ◽  
V. E. Gough
Keyword(s):  
Laboratory Tests ◽  
Surface Film ◽  
Factors Affecting ◽  
Laboratory Conditions ◽  
Service Conditions ◽  
Exposure Conditions

Abstract Rubber and rubberlike polymers, in common with other materials which deteriorate on exposure to oxidizing or similar agents, eventually crack under normal atmospheric service conditions. The present paper confines itself to the factors affecting the type and appearance of the cracking which eventually occurs when a surface film of a rubber object (particularly when stressed) hardens and deteriorates in strength from any cause whatsoever. The importance of an understanding of the effects of exposure conditions on the character of the cracking produced cannot be too highly emphasized. This is so even if interest is confined solely to simple tests on new protective paints on an acceptance basis rather than research into surface deterioration. It is probable that many protective agencies have been accepted or rejected for extensive production tests because the initial laboratory tests have either not been representative of service or have been inadequate in scope. This still remains a major problem. The theory presented here has gradually taken shape over a period of some ten years and appears to describe adequately the general findings on the whole gamut of cracking, viz., fine check cracking and isolated deep cracks produced under service and laboratory conditions, the latter covering flexing, roof exposure, ozone and similar tests.

The nitrogen status of red and yellow earths in the semiarid tropics as influenced by Caribbean stylo (Stylosanthes hamata) grown at various rates of applied phosphorus

Soil Research ◽  
1986 ◽  
Vol 24 (3) ◽  
pp. 405 ◽  
Author(s):  
ME Probert ◽  
J Williams
Keyword(s):  
Room Temperature ◽  
Soil Analysis ◽  
Nitrogen Supply ◽  
Early Years ◽  
Nitrogen Status ◽  
Mineral N ◽  
Stylosanthes Hamata ◽  
Nitrate N ◽  
Red Earth ◽  
Semiarid Tropics

Changes in the nitrogen status of a red and a yellow earth in the semi-arid tropics of central north Queensland were examined following five years' growth of Stylosanthes hamata pasture under a range of phosphorus inputs. The results highlight the importance of leaching of nitrate-N in these environments. This could be accounted for satisfactorily by a simple water and solute exchange model. Small increases in organic carbon and total nitrogen in soil were restricted to the early years of the pasture phase but were not significantly related to the phosphorus treatments. The nitrogen supply to a test crop of millet, both in the field and for surface 0-10 cm samples cropped in the glasshouse, was enhanced by previous growth of legume, and the magnitude of the effect depended upon the yields of legume grown as influenced by its phosphorus nutrition. In terms of freshly applied ammonium nitrate, the contribution from the legume measured in the field was equivalent to 33 kg N ha-1 for an annual production of 1 t ha-1 of legume dry matter on the red earth, and similarly 38 kg N ha-1 on the yellow earth. Of several methods of soil analysis studied, mineral-N extracted with 1 M KCl, either at room temperature or at boiling point, were the best single predictors of the nitrogen supply as measured by the nitrogen uptake of millet. Evidence is provided to show that forms other than mineral-N also contributed to the nitrogen supply, but none of the methods of soil analysis used was able to quantify this nitrogen arising from mineralisation.

scholarly journals Breeding Biology of Gray-Crowned Tyrannulet in the Monte Desert, Argentina

The Condor ◽  
2000 ◽  
Vol 102 (1) ◽  
pp. 205-210 ◽  
Author(s):  
Eduardo T. Mezquida ◽  
Luis Marone
Keyword(s):  
Incubation Period ◽  
Breeding Season ◽  
Nesting Success ◽  
Nest Failure ◽  
East Central ◽  
Male And Female ◽  
Monte Desert ◽  
Present Information ◽  
Nestling Period ◽  
Wet Tropics

Abstract We present information from 75 nests of Gray-crowned Tyrannulet (Serpophaga griseiceps) found in open Prosopis woodlands of the central Monte desert between 1995 and 1997 and compare it with information corresponding to other species of the genus. Breeding occurred from October to January. Nests are small open cups. Both parents participated in nest building, which lasted 4–7 days. In the Prosopis woodland, 98% of the nests were built in chañar (Geoffroea decorticans), which also is commonly used as a nest plant by S. subcristata in east-central Argentina. Mean clutch size did not vary among years nor within the breeding season, and it was similar to that observed in other Serpophaga. Both male and female shared the 13–15 day incubation period. Hatching was asynchronous. Nestling period lasted 13–14 days, during which both parents reared the chicks. Nesting success (26%) appeared to be less than that previously reported for Nearctic open-nesters (50–60%), and Neotropical open-nesters in dry (50%) and wet tropics (35%). Egg and nestling predation were the main cause of nest failure.

Fate of14C-Labeled Soybean and Corn Pesticides in Tropical Soils of Brazil under Laboratory Conditions

2002 ◽  
Vol 50 (16) ◽  
pp. 4619-4627 ◽  
Author(s):  
Volker Laabs ◽  
Wulf Amelung ◽  
Gunnar Fent ◽  
Wolfgang Zech ◽  
Roland Kubiak
Keyword(s):  
Tropical Soils ◽  
Laboratory Conditions
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