نتایج جستجو برای: soil fixation
تعداد نتایج: 231700 فیلتر نتایج به سال:
Global climate change has accelerated the pace of glacial retreat in high-latitude and high-elevation environments, exposing lands that remain devoid of vegetation for many years. The exposure of 'new' soil is particularly apparent at high elevations (5000 metres above sea level) in the Peruvian Andes, where extreme environmental conditions hinder plant colonization. Nonetheless, these seemingl...
Microbial communities drive biogeochemical cycles in agricultural areas by decomposing organic materials and converting essential nutrients. Organic amendments improve soil quality by increasing the load of essential nutrients and enhancing the productivity. Additionally, fresh water used for irrigation can affect soil quality of agricultural soils, mainly due to the presence of microbial conta...
Cyanobacteria play an important role in increasing soil fertility as one of the biological soil crust in rangelands. They have a significant effect on improving soil fertility because of nitrogen and carbon fixation. In this study, the effect of different concentrations of cyanobacteria as one of the soil biomasses and finally to determine the best concentration for optimizing soil fertility in...
atmospheric nitrogen fixation as an exclusive phenomenon is accomplished by nitrogenase enzyme of prokaryotic microorganisms namely diazotrophs including bacteria, actinomycets and cyanobacteria. nitrogen fixation is accomplished as form of symbiotic, associative and free-living systems. in free-living systems nitrogen is fixed without the help of plants. azotobacter, the first diazotroph was d...
BACKGROUND Biological soil crusts are common components of desert ecosystem; they cover ground surface and interact with topsoil that contribute to desertification control and degraded land restoration in arid and semiarid regions. METHODOLOGY/PRINCIPAL FINDINGS To distinguish the changes in topsoil affected by biological soil crusts, we compared topsoil properties across three types of succe...
Increases in global temperature are likely to have effects on the nitrogen cycle, including thosemediated through effects on legumes, which have a role in the N cycle by fixing N2. These effects may alter plant functioning and community structure, especially in N-limited ecosystems.Wemanipulated temperature and plant diversity in the field to investigate the effects of elevated temperature on a...
Symbiotic nitrogen (N) fixing trees are absent from old-growth temperate and boreal ecosystems, even though many of these are N-limited. To explore mechanisms that could select against N fixation in N-limited, old-growth ecosystems, we developed a simple resource-based evolutionary model of N fixation. When there are no costs of N fixation, increasing amounts of N fixation will be selected for ...
That some of the potassium added in the form of fertilizers or otherwise becomes fixed in the soil had been known for a long time. With the clarification of the phenomena of base exchange in soils by Gedroiz it was revealed that the K-ion is fixed in the exchange complex not only in replaceable but also in non-replaceable form. A review of the work in this connection may be found in the paper b...
Initially after catastrophic disturbance ecosystems undergo a build-up phase but in the long term absence of catastrophic disturbance ecosystems can enter a phase of decline called ecosystem retrogression. It is characterised by reduced productivity, decomposition rates and rates of nutrient cycling as a consequence of nutrient limitation. Over the course of long-term soil development, phosphor...
Heavy metals have deleterious the effects on nodulation and N2 fixation of Rhizobium- Legume symbiosis, due to their inhibitory effects on the growth and activity of both symbionts. This research has been undertaken to evaluate the effect of Cd tolerance of native rhizobial strains on diminution of the Cd detrimental effects on Sinorhizobium meliloti-alfalfa symbiosis. For this purpose, a green...
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