Soils, crop nutrient status and nutrient dynamics on small-holder farms in central Tibet, China

2011 ◽  
Vol 348 (1-2) ◽  
pp. 219-229 ◽  
Author(s):  
Nicholas G. Paltridge ◽  
Samantha P. P. Grover ◽  
Liu Gouyi ◽  
Jin Tao ◽  
Murray J. Unkovich ◽  
...  
Keyword(s):  
Nutrient Dynamics ◽  
Nutrient Status ◽  
Central Tibet ◽  
Small Holder

DairyMod and EcoMod: biophysical pasture-simulation models for Australia and New Zealand

2008 ◽  
Vol 48 (5) ◽  
pp. 621 ◽  
Author(s):  
I. R. Johnson ◽  
D. F. Chapman ◽  
V. O. Snow ◽  
R. J. Eckard ◽  
A. J. Parsons ◽  
...  
Keyword(s):  
New Zealand ◽  
Nutrient Dynamics ◽  
Irrigation Management ◽  
Management Strategies ◽  
Simulation Models ◽  
Nutrient Status ◽  
Pasture Management ◽  
Management Options ◽  
Recent Developments ◽  
Fertiliser Application

DairyMod and EcoMod, which are biophysical pasture-simulation models for Australian and New Zealand grazing systems, are described. Each model has a common underlying biophysical structure, with the main differences being in their available management options. The third model in this group is the SGS Pasture Model, which has been previously described, and these models are referred to collectively as ‘the model’. The model includes modules for pasture growth and utilisation by grazing animals, water and nutrient dynamics, animal physiology and production and a range of options for pasture management, irrigation and fertiliser application. Up to 100 independent paddocks can be defined to represent spatial variation within a notional farm. Paddocks can have different soil types, nutrient status, pasture species, fertiliser and irrigation management, but are subject to the same weather. Management options include commonly used rotational grazing management strategies and continuous grazing with fixed or variable stock numbers. A cutting regime simulates calculation of seasonal pasture growth rates. The focus of the present paper is on recent developments to the management routines and nutrient dynamics, including organic matter, inorganic nutrients, leaching and gaseous nitrogen losses, and greenhouse gases. Some model applications are presented and the role of the model in research projects is discussed.

scholarly journals Stable Isotopic Evidence for Nutrient Rejuvenation and Long-Term Resilience on Tikopia Island (Southeast Solomon Islands)

2021 ◽  
Vol 13 (15) ◽  
pp. 8567
Author(s):  
Jillian A. Swift ◽  
Patrick V. Kirch ◽  
Jana Ilgner ◽  
Samantha Brown ◽  
Mary Lucas ◽  
...  
Keyword(s):  
Land Use ◽  
Nutrient Dynamics ◽  
Solomon Islands ◽  
Isotope Analysis ◽  
Nutrient Status ◽  
Nitrogen Isotope ◽  
External Support ◽  
Deep Time ◽  
Human Land Use

Tikopia Island, a small and relatively isolated Polynesian Outlier in the Southeast Solomon Islands, supports a remarkably dense human population with minimal external support. Examining long-term trends in human land use on Tikopia through archaeological datasets spanning nearly 3000 years presents an opportunity to investigate pathways to long-term sustainability in a tropical island setting. Here, we trace nutrient dynamics across Tikopia’s three pre-European contact phases (Kiki, Sinapupu, Tuakamali) via stable carbon and nitrogen isotope analysis of commensal Pacific rat (Rattus exulans) and domestic pig (Sus scrofa) bone and tooth dentine collagen. Our results show a decline in δ15N values from the Kiki (c. 800 BC-AD 100) to Sinapupu (c. AD 100–1200) phases, consistent with long-term commensal isotope trends observed on other Polynesian islands. However, increased δ15N coupled with lower δ13C values in the Tuakamali Phase (c. AD 1200–1800) point to a later nutrient rejuvenation, likely tied to dramatic transformations in agriculture and land use at the Sinapupu-Tuakamali transition. This study offers new, quantifiable evidence for deep-time land and resource management decisions on Tikopia and subsequent impacts on island nutrient status and long-term sustainability.

scholarly journals Assessment of Soil Nutrient Status under Different Cropping Systems in Khotang, Nepal

2019 ◽  
Vol 7 (3) ◽  
pp. 341-346
Author(s):  
Pawan Devkota ◽  
Dipendra Aryal ◽  
Baburam Khanal
Keyword(s):  
Nutrient Dynamics ◽  
Cropping Systems ◽  
Block Design ◽  
Cropping System ◽  
Soil Nutrient ◽  
Nutrient Status ◽  
Available Phosphorus ◽  
Land Use Pattern ◽  
P Content ◽  
Huge Impact

Availability of plant nutrients in rhizosphere is directly influenced by types of crop grown and land use pattern. The experiment was conducted in Diktel Rupakot Majhuwagadhi Municipality, Khotang, Nepal to assess the soil nutrients dynamics as influenced by different cropping system. Five different cropping systems (Rice – Wheat, Maize – Millet, Maize – Vegetables, Ginger and Cardamom) were selected as treatments and all treatments were replicated for five times for blocking in Randomized Complete Block Design. Soil samples from 0-15 cm depth were collected from each site and evaluated for soil pH, soil organic carbon (SOC), total nitrogen (N), available phosphorus (P), and available potassium (K). All the tested parameters except N were found to be significantly affected by cropping system. Soil in all five cropping systems were found acidic (pH<6.5) in nature with pH ranging from 5.180-6.640. The SOC was recorded highest (3.102%) from Cardamom based system and lowest amount of SOC was observed in Ginger based system. The highest amount of P (32.14 mg/kg) was reported in Maize – Vegetables cropping system and lowest P content (5.72 mg/kg) was recorded from Cardamom based system. P content in Ginger based system (31.51 mg/kg) was statistically at par with that of Rice – Wheat system. The highest K content (306.50 mg/kg) was recorded from Maize – Vegetable cropping system and lowest K content (34.80 mg/kg) was observed in Cardamom based system which is statistically similar to Rice –Wheat (35.70 mg/kg) and Maize –Millet systems (77.20 mg/kg). The result indicated that cropping systems have huge impact on plant nutrient dynamics in soil. Int. J. Appl. Sci. Biotechnol. Vol 7(3): 341-346  

scholarly journals Impact of Dinophysis acuminata Feeding Mesodinium rubrum on Nutrient Dynamics and Bacterial Composition in a Microcosm

Toxins ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 443 ◽  
Author(s):  
Han Gao ◽  
Chenfeng Hua ◽  
Mengmeng Tong
Keyword(s):  
Bacterial Community ◽  
Nutrient Dynamics ◽  
Environmental Changes ◽  
Prey Availability ◽  
Feeding Activity ◽  
Nutrient Status ◽  
Prey Cell ◽  
Mesodinium Rubrum ◽  
Dinophysis Acuminata ◽  
Study Laboratory

The development of Dinophysis populations, producers of diarrhetic shellfish toxins, has been attributed to both abiotic (e.g., water column stratification) and biotic (prey availability) factors. An important process to consider is mixotrophy of the Dinophysis species, which is an intensive feeding of the Mesodinium species for nutrients and a benefit from kleptochloroplasts. During the feeding process, the nutritional status in the environment changes due to the preference of Mesodinium and/or Dinophysis for different nutrients, prey cell debris generated by sloppy feeding, and their degradation by micro-organisms changes. However, there is little knowledge about the role of the bacterial community during the co-occurrence of Mesodinium and Dinophysis and how they directly or indirectly interact with the mixotrophs. In this study, laboratory experiments were performed to characterize the environmental changes including those of the prey present, the bacterial communities, and the ambient dissolved nutrients during the co-occurrence of Mesodinium rubrum and Dinophysis acuminata. The results showed that, during the incubation of the ciliate prey Mesodinium with its predator Dinophysis, available dissolved nitrogen significantly shifted from nitrate to ammonium especially when the population of M. rubrum decayed. Growth phases of Dinophysis and Mesodinium greatly affected the structure and composition of the bacterial community. These changes could be mainly explained by both the changes of the nutrient status and the activity of Dinophysis cells. Dinophysis feeding activity also accelerated the decline of M. rubrum and contamination of cultures with okadaic acid, dinophysistoxin-1, and pectenotoxin-2, but their influence on the prokaryotic communities was limited to the rare taxa (<0.1%) fraction. This suggests that the interaction between D. acuminata and bacteria is species-specific and takes place intracellularly or in the phycosphere. Moreover, a majority of the dominant bacterial taxa in our cultures may also exhibit a metabolic flexibility and, thus, be unaffected taxonomically by changes within the Mesodinium-Dinophysis culture system.

Lhasa and Central Tibet.—III

1905 ◽  
Vol 59 (1524supp) ◽  
pp. 24420-24422
Author(s):  
G. Ts. Tsybikoff
Keyword(s):  
Central Tibet

Sidrophore Production and Phosphate Solubilization by Bacillus cereus and Pseudomonas fluorescens Isolated from Iraqi Soils and Soil Characterization

2018 ◽  
Vol 9 (4) ◽  
Author(s):  
Zaid Raad Abbas ◽  
Aqeel Mohammed Majeed Al-Ezee ◽  
Sawsan H
Keyword(s):  
Bacillus Cereus ◽  
Pseudomonas Fluorescens ◽  
Phosphate Solubilization ◽  
Bacterial Species ◽  
Nutrient Status ◽  
Bacterial Count ◽  
Soil Samples ◽  
Phosphate Solubilizing Bacteria ◽  
Clear Zone ◽  
Zone Formation

This study was conducted to explore the ability of Pseudomonas fluorescens and Bacillus cereus to solubilizing a phosphate in soil for enhancing the planting growth and, its relation with soill characterization. The isolates were identified as P.fluorescens and B. cereus using convential analysis and, its phosphate solubilization ability and sidrophore was shown by the clear zone formation on National Botanical Research Institute���s Phosphate medium. Moreover, Pseudomonas fluorescens isolates (n = 9) and three of B. cereus isolated from agricultural area in Baghdad university, Mustansiriyah university and Diyala bridge. Results displayed that bacterial count were varied in soil samples according to their region, and ranging from 30 to 60 *10 2 CFU/g in Baghdad university soil to 10���20 *10 2 CFU/g in Mustansiriyah university soil, the Baghdad soil macronutrient which included: NH4, NO3, P, and K were, 8.42, 20.53, 19.09, 218.73 respectively, While the physio analysis revealed that the mean of pH was 7.3 and EC was 8.63. on the other hand the micronutrient analysis indicated that the soil samples were included Ca, Fe, Mn, Zn and Cu which gave their mean 5025.9, 8.9, 4.9, 0.5 and 1.5 respectevily. Results revealed that all isolated bacteria (9 isolates of P.fluorescens and three isolates of B. cereus gave ahalo zone which mean their ability to be phosphate solubilizing bacteria at 100%. Results revealed that all isolated bacteria were detected a ability to produce high levels from chelating agents (siderophores)) by P.fluorescens and. B cereus at 100%, when appeared ahalo clear zone. Furthermore, the high levels of phosphate solubilization and siderophore production were grouped in bacterial species isolated from Iraqi soils. might be attributed to many soil factors such as soil nutrient status, soil acidity, water content, organic matter and soil enzyme activities.

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