Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
15,753
result(s) for
"Nitrogen cycle"
Sort by:
Microbial roles in the terrestrial and aquatic nitrogen cycle—implications in climate change
Abstract
Nitrogen, as an essential component for living organisms, is the primary limiting nutrient on Earth. The availability and effective utilization of nitrogenous compounds for metabolic and other essential biochemical reactions are dependent on the myriad and phylogenetically diverse microbial communities. The microorganisms harmoniously interact and participate in every reaction of the nitrogen cycle to continuously transform nitrogen into its various bio-available forms. Research on the nitrogen cycle continues to disclose that there are many reactions that remain unknown. In this review, we summarize the recent discoveries that have contributed to advancing our understanding of the microbial involvement in reactions of the nitrogen cycle in soil and aquatic systems that influence climate change. Additionally, the mini-review highlights, which anthropogenic activities cause disturbances in the nitrogen cycle and proposes how beneficial microbes may be harnessed to replenish nitrogen in agricultural ecosystems.
Soil Microorganisms regulate the nitrogen cycle and influence climate change.
Journal Article
The nitrogen cycle
\"Nitrogen is a common element found as a gas in the air we breathe as well as in other forms in water and soil. Nitrogen is essential for all life on Earth. This informative book explains how the Earth's supply of nitrogen moves in different forms in a cycle from the air to the soil to living things. Highly readable text and supportive images help explain such processes as fixation, nitrification, and dentrification, as well as the important role of bacteria in the nitrogen cycle. Feature boxes highlight examples of the ways in which human activity, such as adding more nitrogen to the soil to make plants grow faster, releases harmful greenhouse gases into the air interfering with the nitrogen cycle. Readers are encouraged to find ways to take action and find solutions\"-- Provided by publisher.
Book
Dynamic carbon-nitrogen coupling under global change
Carbon-nitrogen coupling is a fundamental principle in ecosystem ecology. However, how the coupling responds to global change has not yet been examined. Through a comprehensive and systematic literature review, we assessed how the dynamics of carbon processes change with increasing nitrogen input and how nitrogen processes change with increasing carbon input under global change. Our review shows that nitrogen input to the ecosystem mostly stimulates plant primary productivity but inconsistently decreases microbial activities or increases soil carbon sequestration, with nitrogen leaching and nitrogenous gas emission rapidly increasing. Nitrogen fixation increases and nitrogen leaching decreases to improve soil nitrogen availability and support plant growth and ecosystem carbon sequestration under elevated CO
2
and temperature or along ecosystem succession. We conclude that soil nitrogen cycle processes continually adjust to change in response to either overload under nitrogen addition or deficiency under CO
2
enrichment and ecosystem succession to couple with carbon cycling. Indeed, processes of both carbon and nitrogen cycles continually adjust under global change, leading to dynamic coupling in carbon and nitrogen cycles. The dynamic coupling framework reconciles previous debates on the “uncoupling” or “decoupling” of ecosystem carbon and nitrogen cycles under global change. Ecosystem models failing to simulate these dynamic adjustments cannot simulate carbon-nitrogen coupling nor predict ecosystem carbon sequestration well.
Journal Article
Effects of different nitrogen applications and straw return depth on straw microbial and carbon and nitrogen cycles in paddy fields in the cool zone
Straw is an important source of organic fertilizer for soil enrichment, however, the effects of different nitrogen(N) application rates and depths on straw decomposition microorganisms and carbon and nitrogen cycling under full straw return conditions in cool regions of Northeast China are not clear at this stage. In this paper, we applied macro-genome sequencing technology to investigate the effects of different N application rates (110 kg hm
−2
, 120 kg hm
−2
, 130 kg hm
−2
, 140 kg hm
−2
, 150 kg hm
−2
) and depths (0–15 cm, 15–30 cm) on straw decomposing microorganisms and N cycling in paddy fields in the cool zone of Northeast China. The results showed that (1) about 150 functional genes are involved in the carbon cycle process of degradation during the degradation of returned straw, of which the largest number of functional genes are involved in the methane production pathway, about 42, the highest abundance of functional genes involved in the citric acid cycle pathway. There are 22 kinds of functional genes involved in the nitrogen cycle degradation process, among which there are more kinds involved in nitrogen fixation, with 4 kinds. (2) High nitrogen application (150 kg hm
−2
) inhibited the carbon and nitrogen conversion processes, and the abundance of straw-degrading microorganisms and nitrogen-cycling functional genes was relatively high at a nitrogen application rate of 130 kg hm
−2
. (3) Depth-dependent heterogeneity of the microbial community was reduced throughout the vertical space. At 71 days of straw return, the nitrogen cycling function decreased and some carbon functional genes showed an increasing trend with the increase of straw return depth. The nitrogen cycle function decreased with the increase of straw returning depth. The microbial community structure was best and the abundance of functional genes involved in the nitrogen cycling process was higher under the conditions of 0–15 cm of returning depth and 130 kg hm
−2
of nitrogen application.
Journal Article
The California nitrogen assessment : challenges and solutions for people, agriculture, and the environment
\"Nitrogen is indispensable to all life on Earth. However, humans now dominate the nitrogen cycle and nitrogen emissions resulting from human activity involve real costs: water and air pollution, climate change, and detrimental effects for human health, biodiversity, and natural habitat. Too little nitrogen limits ecosystem processes, while too much nitrogen transforms ecosystems profoundly. The California Nitrogen Assessment is the first comprehensive accounting of nitrogen flows, practices, and policies for California; encompassing all nitrogen flows--not just those associated with agriculture--and their impacts on ecosystem services and human wellbeing. How California handles issues of nitrogen will be of interest nationally and internationally, and the goal of the assessment is to more effectively link science with action and to produce information that informs both future policy and solutions to nitrogen pollution. This book also provides a model for application of integrated ecosystem assessment methods at regional and state (sub-national) levels.\"--Provided by publisher.
Book
Adjustment of microbial nitrogen use efficiency to carbon:nitrogen imbalances regulates soil nitrogen cycling
Microbial nitrogen use efficiency (NUE) describes the partitioning of organic N taken up between growth and the release of inorganic N to the environment (that is, N mineralization), and is thus central to our understanding of N cycling. Here we report empirical evidence that microbial decomposer communities in soil and plant litter regulate their NUE. We find that microbes retain most immobilized organic N (high NUE), when they are N limited, resulting in low N mineralization. However, when the metabolic control of microbial decomposers switches from N to C limitation, they release an increasing fraction of organic N as ammonium (low NUE). We conclude that the regulation of NUE is an essential strategy of microbial communities to cope with resource imbalances, independent of the regulation of microbial carbon use efficiency, with significant effects on terrestrial N cycling.
Nitrogen availability in soils is predominantly controlled by microorganisms, yet our understanding of their organic nitrogen use is limited. Mooshammer
et al.
show that microbial nitrogen use efficiency is dependent on resource stoichiometry and substrate type.
Journal Article
high-resolution assessment on global nitrogen flows in cropland
Crop production is the single largest cause of human alteration of the global nitrogen cycle. We present a comprehensive assessment of global nitrogen flows in cropland for the year 2000 with a spatial resolution of 5 arc-minutes. We calculated a total nitrogen input (IN) of 136.60 trillion grams (Tg) of N per year, of which almost half is contributed by mineral nitrogen fertilizers, and a total nitrogen output (OUT) of 148.14 Tg of N per year, of which 55% is uptake by harvested crops and crop residues. We present high-resolution maps quantifying the spatial distribution of nitrogen IN and OUT flows, soil nitrogen balance, and surface nitrogen balance. The high-resolution data are aggregated at the national level on a per capita basis to assess nitrogen stress levels. The results show that almost 80% of African countries are confronted with nitrogen scarcity or nitrogen stress problems, which, along with poverty, cause food insecurity and malnutrition. The assessment also shows a global average nitrogen recovery rate of 59%, indicating that nearly two-fifths of nitrogen inputs are lost in ecosystems. More effective management of nitrogen is essential to reduce the deleterious environmental consequences.
Journal Article