Negative impacts of excessive nitrogen fertilization on the abundance and diversity of diazotrophs in black soil under maize monocropping

Geoderma ◽  
2021 ◽  
Vol 393 ◽  
pp. 114999
Author(s):  
La Chen ◽  
Ke Ke Li ◽  
Wen Jun Shi ◽  
Xiao Lin Wang ◽  
En Tao Wang ◽  
...  
Keyword(s):  
Nitrogen Fertilization ◽  
Black Soil ◽  
Negative Impacts ◽  
Abundance And Diversity

scholarly journals Negative impacts of excessive nitrogen fertilization on the abundance and diversity of diazotrophs in black soil with monocropping maize

2020 ◽  
Author(s):  
La Chen ◽  
Keke Li ◽  
Wenjun Shi ◽  
Xiaolin Wang ◽  
Entao Wang ◽  
...  
Keyword(s):  
Soil Ph ◽  
Nitrogen Fertilizer ◽  
Nitrogen Fertilization ◽  
Black Soil ◽  
Maize Rhizosphere ◽  
N Input ◽  
Use Efficiency ◽  
Abundance And Diversity ◽  
Diazotrophic Community

Abstract Background: Excessive nitrogen fertilizer input and low nitrogen fertilizer use efficiency in maize in China are serious ecological and economic problems, which might affect the procedures in the nitrogen cycle. To reveal the effects of long-term excessive nitrogen fertilization on diazotrophs in maize rhizosphere and bulk soil, we performed a long-term (five-year) N-input experiment (N rates from 0 to 300 kg N ha -1 ) in black soil maize in northeast China. The effect of N fertilizer application rates on the abundance, structure and compositions of diazotrophic community in both the bulk soil and rhizosphere of maize were investigated by Real-time quantitative PCR and high-throughput sequencing, and a structural equation model was constructed based on this study.Results: 1) Excessive N fertilization significantly reduced the abundance and diversity of diazotrophs. 2) The accumulation of Sphingobium was correlated positively with soil nitrate concentration and soil EC, and negatively with soil pH. The contrast correlation was found in Burkholderia . 3) Diazotrophs were enriched in maize rhizosphere, but the diversity and compositions of diazotrophic community were less affected by maize rhizosphere effect. 4) The enriched Bradyrhizobium and Methylobacterium in maize rhizosphere showed a significant positive correlation with of maize plant biomass. Conclusions: Our results suggest that through affecting soil pH, nitrate and EC values, long-term excessive N input increase Sphingobium accumulation and reduce the abundance of beneficial diazotrophs such as Bradyrhizobium and Burkholderia ，which contribute to the decreased nitrogen use efficiency.

scholarly journals Time-since-invasion increases native mesoherbivore feeding rates on the invasive alga, Sargassum muticum (Yendo) Fensholt

2017 ◽  
Vol 98 (8) ◽  
pp. 1935-1944 ◽  
Author(s):  
Martyn Kurr ◽  
Andrew J. Davies
Keyword(s):  
Invasive Plants ◽  
Enemy Release Hypothesis ◽  
Sargassum Muticum ◽  
Enemy Release ◽  
Feeding Rates ◽  
Herbivore Species ◽  
Feeding Trials ◽  
Negative Impacts ◽  
Abundance And Diversity ◽  
Invasive Alga

Invasive algae can have substantial negative impacts in their invaded ranges. One widely cited mechanism that attempts to explain how invasive plants and algae are often able to spread quickly, and even become dominant in their invaded ranges, is the Enemy Release Hypothesis. This study assessed the feeding behaviours of two species of gastropod herbivore from populations exposed to the invasive alga Sargassum muticum for different lengths of time. Feeding trials, consisting of both choice and no-choice, showed that the herbivores from older stands (35–40 years established) of S. muticum were more likely to feed upon it than those taken from younger (10–19 years established) stands. These findings provide evidence in support of the ERH, by showing that herbivores consumed less S. muticum if they were not experienced with it. These findings are in accordance with the results of other feeding-trials with S. muticum, but in contrast to research that utilizes observations of herbivore abundance and diversity to assess top-down pressure. The former tend to validate the ERH, and the latter typically reject it. The potential causes of this disparity are discussed, as are the importance of palatability, herbivore species and time-since-invasion when considering research into the ERH. This study takes an important, yet neglected, approach to the study of invasive ecology.

scholarly journals Wildlife and Ecotourism Contributions for Sustainable Natural Resource Management In and Around Bale Mountains National Park, Southeastern Ethiopia

2020 ◽  
Author(s):  
Sefi Mekonen Ertiban ◽  
Belay Maru
Keyword(s):  
Natural Resources ◽  
National Park ◽  
Sustainable Use ◽  
Secondary Data ◽  
Local Communities ◽  
Cultural Resources ◽  
Job Opportunities ◽  
Sustainable Natural Resource Management ◽  
Negative Impacts ◽  
Abundance And Diversity

Abstract Wildlife and ecotourism resources were assessed in and around Bale Mountains National Park (BMNP) to examine their contribution for sustainable use of natural resources which will improve the livelihood of local communities and conservation of park. Survey questionnaires, interview, field observation and literature reviews were employed to collect primary and secondary data. The analyses of the study revealed that natural and cultural resources such as abundance and diversity of mammals and birds, scenic landscape, cultural and historical attractions and some hotels or lodges at nearby areas are the main ecotourism potential in BMNP. The study also revealed some income generating alternatives or ecotourism potentials which could help to reduce the present degradations of natural resources of the park. About 37.2% of sampled households expressed their interests for diversified livelihood or ecotourism activities. Offering tourist facilities and services and creating job opportunities for members of local communities are the positive impacts of the tourism activities whereas, cutting trees, occurrences of seasonality and leakages are the negative impacts. Reinforcing existing off-agricultural livelihoods, introducing additional alternative options or ecotourism are important strategic directions for sustainable management of natural resources for BMNP and related protected areas.

INFLUENCE OF VARIETY, NITROGEN FERTILIZATION, LOCATION AND YEAR OF GROWTH ON THE NUTRITIVE VALUE OF WHEAT AS DETERMINED BY RAT GROWTH

1963 ◽  
Vol 43 (1) ◽  
pp. 22-30 ◽  
Author(s):  
R. S. Bhatty ◽  
J. P. Bowland ◽  
C. F. Bentley ◽  
S. Zalik
Keyword(s):  
Nitrogen Fertilization ◽  
Nutritive Value ◽  
Wheat Gluten ◽  
Inverse Correlation ◽  
Black Soil ◽  
Food Utilization ◽  
Mineral Supplement ◽  
Wheat Varieties ◽  
Rat Growth ◽  
Feeding Value

The influence of variety, nitrogen fertilization, location (Grey Wooded vs. Black soil) and year of growth on the nutritive value of wheat fed to weanling rats was studied. Methods of dietary supplementation were: (a) no protein or amino acid supplement; (b) 0.6 per cent L-lysine — HCl; (c) wheat gluten to raise the total protein to 20 per cent. A complete vitamin and mineral supplement was added to all diets.Food intake was not influenced by any of the variables. Weight gains for a 2-week period were higher for rats fed Thatcher than for those fed Kenhi wheat (independent of protein content). Location and year of growth also influenced rate of gain. When lysine supplement was added, rats fed fertilized grain grew more rapidly than those fed unfertilized grain. Efficiency of food utilization followed a similar pattern to rate of gain, but varietal differences were less evident.Fifty to eighty per cent of the variation obtained in rat gain was associated with the protein or lysine content of the wheat. An inverse correlation of 0.72 was obtained between the level of protein in the wheat and the percentage of lysine in the protein. As there were no interactions between variety and the other variables, a biological assay with rats could yield useful information on the feeding value of wheat varieties, over and above information obtained from chemical analyses.

scholarly journals Abundance and Diversity of Soybean-Nodulating Rhizobia in Black Soil Are Impacted by Land Use and Crop Management

2014 ◽  
Vol 80 (17) ◽  
pp. 5394-5402 ◽  
Author(s):  
Jun Yan ◽  
Xiao Zeng Han ◽  
Zhao Jun Ji ◽  
Yan Li ◽  
En Tao Wang ◽  
...  
Keyword(s):  
Land Use ◽  
Bradyrhizobium Japonicum ◽  
Crop Management ◽  
Black Soil ◽  
Soil Parameters ◽  
Available Phosphorus ◽  
Content Type ◽  
Rhizobial Diversity ◽  
Abundance And Diversity ◽  
Effects Of Land Use

ABSTRACTTo investigate the effects of land use and crop management on soybean rhizobial communities, 280 nodule isolates were trapped from 7 fields with different land use and culture histories. Besides the knownBradyrhizobium japonicum, three novel genospecies were isolated from these fields. Grassland (GL) maintained a higher diversity of soybean bradyrhizobia than the other cultivation systems. Two genospecies (Bradyrhizobiumspp. I and III) were distributed widely in all treatments, whileBradyrhizobiumsp. II was found only in GL treatment. Cultivation with soybeans increased the rhizobial abundance and diversity, except for the soybean monoculture (S-S) treatment. In monoculture systems, soybeans favoredBradyrhizobiumsp. I, while maize and wheat favoredBradyrhizobiumsp. III. Fertilization decreased the rhizobial diversity indexes but did not change the species composition. The organic carbon (OC) and available phosphorus (AP) contents and pH were the main soil parameters positively correlated with the distribution ofBradyrhizobiumspp. I and II andBradyrhizobium japonicumand negatively correlated withBradyrhizobiumsp. III. These results revealed that different land uses and crop management could not only alter the diversity and abundance of soybean rhizobia, but also change interactions between rhizobia and legume or nonlegume plants, which offered novel information about the biogeography of rhizobia.

scholarly journals Habitat diversity and type govern potential nitrogen loss by denitrification in coastal sediments and differences in ecosystem-level diversities of disparate N2O reducing communities

2020 ◽  
Vol 96 (9) ◽  
Author(s):  
Lea Wittorf ◽  
Fabian Roger ◽  
Christian Alsterberg ◽  
Lars Gamfeldt ◽  
Stefan Hulth ◽  
...  
Keyword(s):  
Nitrogen Loss ◽  
Habitat Type ◽  
Habitat Diversity ◽  
Coastal Sediments ◽  
N2o Reduction ◽  
Filter Function ◽  
Denitrification Activity ◽  
Ecosystem Level ◽  
Negative Impacts ◽  
Abundance And Diversity

ABSTRACT In coastal sediments, excess nitrogen is removed primarily by denitrification. However, losses in habitat diversity may reduce the functional diversity of microbial communities that drive this important filter function. We examined how habitat type and habitat diversity affects denitrification and the abundance and diversity of denitrifying and N2O reducing communities in illuminated shallow-water sediments. In a mesocosm experiment, cores from four habitats were incubated in different combinations, representing ecosystems with different habitat diversities. We hypothesized that habitat diversity promotes the diversity of N2O reducing communities and genetic potential for denitrification, thereby influencing denitrification rates. We also hypothesized that this will depend on the identity of the habitats. Habitat diversity positively affected ecosystem-level diversity of clade II N2O reducing communities, however neither clade I nosZ communities nor denitrification activity were affected. The composition of N2O reducing communities was determined by habitat type, and functional gene abundances indicated that silty mud and sandy sediments had higher genetic potentials for denitrification and N2O reduction than cyanobacterial mat and Ruppia maritima meadow sediments. These results indicate that loss of habitat diversity and specific habitats could have negative impacts on denitrification and N2O reduction, which underpin the capacity for nitrogen removal in coastal ecosystems.

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