scholarly journals Modeled contributions of three types of diazotrophs to nitrogen fixation at Station ALOHA

2007 ◽  
Vol 1 (7) ◽  
pp. 606-619 ◽  
Author(s):  
Nicole L Goebel ◽  
Christopher A Edwards ◽  
Matthew J Church ◽  
Jonathan P Zehr
2016 ◽  
Vol 62 (1) ◽  
pp. 200-216 ◽  
Author(s):  
Daniela Böttjer ◽  
John E. Dore ◽  
David M. Karl ◽  
Ricardo M. Letelier ◽  
Claire Mahaffey ◽  
...  

2004 ◽  
Vol 61 (4) ◽  
pp. 457-463 ◽  
Author(s):  
Cecelia C Sheridan ◽  
Michael R Landry

Abstract Mesozooplankton biomass in the North Pacific Subtropical Gyre (NPSG), as measured by the Hawaii Ocean Time-series program at Station ALOHA (22.45°N 158°W), increased significantly from 1994 to 2002. The changes occurred at a rate of 60 mg DW m−2 yr−1 for night-time collections and 45 mg DW m−2 yr−1 for daytime collections. Principal components analysis indicates that the 9-year trend was driven by an increase in small (0.5–2.0 mm) zooplankton that do not migrate on a diel cycle. This plankton class is known to increase during the summer at Station ALOHA when the water column is most stratified, and a strong summertime response is also apparent within the long-term trend from 1998 through 2002. Both long-term and seasonal changes in zooplankton biomass at Station ALOHA can be linked to an enhanced role of nitrogen fixation in ecosystem productivity. Climate forcing from El Niño–Southern Oscillation (ENSO) events may have influenced nitrogen fixation, general ecosystem productivity, and thus zooplankton biomass in the NPSG. However, it is difficult to evaluate the effect of climate cycles in this region without the benefit of a longer time-series at Station ALOHA. Because biomass trends in higher-level consumers like mesozooplankton can have cascading influences on lower levels, understanding the relative roles of bottom-up climate influences and top-down trophic processes will be important in resolving long-term trends in community composition and structure in the subtropical North Pacific Ocean.


2015 ◽  
Vol 525 ◽  
pp. 41-51 ◽  
Author(s):  
PLM Cook ◽  
V Evrard ◽  
RJ Woodland

Author(s):  
S.F. Ledgard ◽  
G.J. Brier ◽  
R.N. Watson

Clover cultivars grown with ryegrass were compared in an establishment year under dairy cow grazing. There was no difference in total annual productton but summer production was greater with Pawera red clover and with Kopu or Pitau white clovers. Clovers differed little in the proportion of nitrogen fixed, except during summer when values were highest for Pawera. Pawera was less prone to nematode attack than white clover cultivars but was more susceptible to clover rot. Resident clovers and high buried seed levels (e.g., 11-91 kg/ha) made introduction of new clover cultivars difficult. Sown clovers established best (50-70% of total clover plants) when drilled into soil treated with dicamba and glyphosate. Keywords: white clover, red clover, nematodes. nitrogen fixation, pasture renovation


GIS Business ◽  
2019 ◽  
Vol 14 (6) ◽  
pp. 425-431
Author(s):  
Subin Thomas ◽  
Dr. M. Nandhini

Biofertilizers are fertilizers containing microorganisms that promote plant growth by improving the supply of nutrients to the host plant. The supply of nutrients is improved naturally by nitrogen fixation and solubilizing phosphorus. The living microorganisms in biofertilizers help in building organic matter in the soil and restoring the natural nutrient cycle. Biofertilizers can be grouped into Nitrogen-fixing biofertilizers, Phosphorous-solubilizing biofertilizers, Phosphorous-mobilizing biofertilizers, Biofertilizers for micro nutrients and Plant growth promoting rhizobacteria. This study conducted in Kottayam district was intended to identify the awareness and acceptance of biofertilizers among the farmers of the area. Data have been collected from 120 farmers by direct interviews with structured questionnaire.


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