Zone Of High Productivity Research Articles

The Impact of Crop Year and Crop Density on the Production of Sunflower in Site-Specific Precision Farming in Hungary

Sunflower is considered a plant with extraordinary adaptability. However, the conditions of growing sunflower function as a limiting factor in its production. The hybrids used in production tolerate weather variability to a different level and utilise the nutrient and water resources of the soil, while the yield is also affected by the number of plants per hectare. In this study, the authors attempted to observe the environmental effects influencing sunflower cultivation, the heterogeneous productivity zones of the given production site and the correlation of the number of seeding plants used under various farm practices. The average rainfall of 2021 and the dry weather of 2022 created suitable conditions for examining the yearly weather effect. In the selected experimental areas, three distinguishable zones were defined in terms of productivity. In each productivity zone, three crop density steps were used in four replicates. Based on the performed comparative tests, the rainy year of 2021 resulted higher yield than the drier year of 2022 in the average- and high productivity zones, while in the low-productivity zone, higher yields were harvested under the drier conditions of 2022 than in the rainy year of 2021. In 2021, with the improvement in productivity, the obtained yield was also higher. However, in 2022, this clarity could not be demonstrated. In the zones with low productivity, identical yield results were observed in both weather conditions. Based on the examination of the obtained results, it was shown that the effect of weather conditions and the given number of plants have a smaller influence on the yield results of low-productivity zones, while these factors have a greater influence on the yields of high-productivity zones.

Soil Quality Assessment of Sesame-Growing Soils with Different Productivity in the Northern Telangana Zone, India

Present study was carried out in major sesame growing areas of Northern Telangana zone in districts namely; Nizamabad, Jagtial, Nirmal and Kamareddy. The main objective of this study is to assess the soil quality and to find out the relation between sesame yield and soil quality index. Based on the seed yield data of sesame, the above-mentioned districts were divided into high, medium and low productivity zones. 50 samples from each productivity zone with a total of 150 surface soil samples (0-15 cm were collected and analysed for various physical, physico-chemical, chemical and biological properties. Physical properties included texture, bulk density and water holding capacity. Physico-chemical properties like pH, EC and organic carbon were analysed. Chemical properties of soil namely available nitrogen, available phosphorus, available potassium, available sulphur, exchangeable bases like exchangeable calcium and magnesium, potassium and sodium, available micronutrients like iron, copper, manganese and zinc were analysed. Biological properties like urease, acid and alkaline phosphatase and labile carbon were analysed. Principal component analysis, minimum dataset was derived which contained available nitrogen, sand, pH, available phosphorus, exchangeable calcium and magnesium and urease with 70.81% variance. These are identified as the key indicators of soil quality. Mean soil quality index values were 0.669, 0.549 and 0.443 for high, medium and low sesame productivity zones respectively and is in the order of high>medium>low sesame productivity zones. Percent contribution of MDS to SQI are in the order of, available nitrogen (44.44%> pH (16.85% >exchangeable calcium (9.87%> exchangeable magnesium (8.89%> urease (7.86%> available phosphorus (7.38% > sand (4.89%. This study concluded that the SQI was more significantly positively correlated with sesame yield, which revealed that soil variables from the minimum data set had biological significance and effectively evaluated the status of the sesame growing soils of Northern Telangana Zone.

Assessment of Soil Variables under Different Sesame Productivities of Northern Telangana Zone

A survey was carried out in major sesame-growing areas of Northern Telangana Zone in high, medium and low productivity zones of districts namely Nizamabad, Jagtial, Nirmal and Kamareddy. 50 surface soil samples (0-15 cm) were collected from each zone and a total of 150 surface soil samples were analyzed for various physical, physicochemical and chemical properties the results showed that the bulk density ranged from 1.10 to 1.56 Mg m-3, from 1.20 to 1.60 Mg m-3 and from 1.20 to 1.63 Mg m-3 in high, medium and low productivity zones respectively. Water holding capacity ranged from 30.00 to 56.80%, from 20.80 to 56.50% and from 19.60 to 51.70% in high, medium and low productivity zones respectively. pH ranged from 7.11 to 7.82, from 6.45 to 8.51 and from 6.81 to 7.46 in high, medium and low productivity zones respectively. EC ranged from 0.32 to 0.46 d Sm-1, from 0.32 to 0.56 d Sm-1 and from 0.12 to 0.56 d Sm-1 in high, medium and low productivity zones respectively. Organic carbon ranged from 0.48 to 1.08%, from 0.23 to 0.72% and from 0.21 to 0.64% in high, medium and low productivity zones respectively. Available nitrogen ranged from 176.20 to 279.70 kg ha-1, from 116.50 to 261.50 kg ha-1 and from 76.40 to 139.80 kg ha-1 in high, medium and low productivity zones respectively. Available phosphorus ranged from 13.41 to 82.33 kg ha-1, from 11.81 to 64.71 kg ha-1 and from 19.98 to 49.06 kg ha-1 in high, medium and low productivity zones respectively. Available potassium ranged from 213.00 to 562.00 kg ha-1, from 126.25 to 585.00 kg ha-1 and from 182.50 to 562.50 kg ha-1 in high, medium and low productivity zones respectively.

Microbially induced sedimentary structures from the Ediacaran of Anti-Atlas, Morocco

The Eastern Anti-Atlas of Morocco hosts an early Ediacaran turbiditic series (Saghro Group) (630–600 Ma) unconformably overlain by thick late Ediacaran (580–550 Ma) terrestrial volcano-clastic formations (Ouarzazate Supergroup), with thin and geographically limited paralic shallow marine sedimentary rocks.This paper presents the first description of structures related to the former presence of extensive microbial mats developed in marine, fluvial, and lacustrine environments during the Ediacaran in the Eastern Anti-Atlas. These microbially induced sedimentary structures (MISS) are largely found in well-laminated fine- to coarse-grained sandstone and sandy-carbonate. They also cover vast bedding planes and occur in almost all sedimentary successions. MISS types include: gas domes, wrinkle structures, reticulate patterns, overflips and roll-ups, multidirectional linear ridges, sand cracks and biolaminated deposits. Based on morphology and petrographic macro and microfabrics, these microbially induced structures are very similar to those of modern photosynthetic cyanobacteria mats. Together with previously reported stromatolites, these newly reported microbial mat structures could have played an important ecological role in stabilizing siliciclastic sediments, as well as sustaining localized zones of high oxygen production in the Ediacaran marine and terrestrial paleoenvironments of the Anti-Atlas. The widespread geographic distribution and consistent occurrence of microbially induced sedimentary structures (MISS) in fluvial and lacustrine sediments present compelling paleontological evidence supporting the extensive greening of the land surface during the late Precambrian period.

Seismic characterization of fault and fractures in deep buried carbonate reservoirs using CNN-LSTM based deep neural networks

Geologic structures such as faults and fractures play a vital role in reservoir development studies. Fault and fracture identification requires high-quality seismic amplitude data with good resolution and a high signal-to-noise ratio (SNR). An anticline fault-controlled carbonate structure in North China contains significant reserves of hydrocarbons. However, the heterogeneity of deeply buried carbonates (burial depth > 4000 m) results in poor resolution and low SNR of seismic amplitude data, making it challenging to distinguish fault edge characteristics under the buried structures. In this study, we apply an inverse Q-filtering method based on the Gabor transform and structure-oriented filtering to compensate for the weak signal of the seismic events and enhance the SNR under the deep buried carbonate rocks. We investigated fault and adjacent fracture zones in structurally complex deeply buried carbonate reservoirs by extracting seismic fracture attributes (fault likelihood, eigenvalue coherence, and curvature) and feedforward neural network spatial fracture distribution from high-resolution seismic amplitude data. Moreover, a fracture density prediction model based on seismic attributes, CNN (convolutional neural network), and LSTM (long short-term memory) is developed to predict spatial fracture density. The predicted fracture density results are verified with seismic fracture attributes, geological modeling, and FMI (formation micro-imager) logs. This integrated workflow can assist in identifying high-production zones in structurally complex and deeply buried carbonates reservoirs.

Isotopes illustrate vertical transport of anthropogenic Pb by reversible scavenging within Pacific Ocean particle veils

Reversible scavenging, the oceanographic process by which dissolved metals exchange onto and off sinking particles and are thereby transported to deeper depths, has been well established for the metal thorium for decades. Reversible scavenging both deepens the elemental distribution of adsorptive elements and shortens their oceanic residence times in the ocean compared to nonadsorptive metals, and scavenging ultimately removes elements from the ocean via sedimentation. Thus, it is important to understand which metals undergo reversible scavenging and under what conditions. Recently, reversible scavenging has been invoked in global biogeochemical models of a range of metals including lead, iron, copper, and zinc to fit modeled data to observations of oceanic dissolved metal distributions. Nonetheless, the effects of reversible scavenging remain difficult to visualize in ocean sections of dissolved metals and to distinguish from other processes such as biological regeneration. Here, we show that particle-rich "veils" descending from high-productivity zones in the equatorial and North Pacific provide idealized illustrations of reversible scavenging of dissolved lead (Pb). A meridional section of dissolved Pb isotope ratios across the central Pacific shows that where particle concentrations are sufficiently high, such as within particle veils, vertical transport of anthropogenic surface-dissolved Pb isotope ratios toward the deep ocean is manifested as columnar isotope anomalies. Modeling of this effect shows that reversible scavenging within particle-rich waters allows anthropogenic Pb isotope ratios from the surface to penetrate ancient deep waters on timescales sufficiently rapid to overcome horizontal mixing of deep water Pb isotope ratios along abyssal isopycnals.

Enhancing sustainable agri-food systems using multi-nutrient fertilizers in Kenyan smallholder farming systems

Persistent food insecurity in the global south has triggered calls for sustainable development worldwide. Moreover, more than a quarter of the world's population suffers from micronutrient deficiencies or hidden hunger. The population bulge, declining soil fertility and inadequate/inappropriate use of farm inputs in Sub-Saharan Africa place it in a precarious position. Multi-nutrient fertilizer blends have been mooted as a key innovation in closing yield gaps and boosting food and nutrition security. This study assessed the extent of multi-nutrient fertilizer blends utilization and yield response across agroecological zones and their on-farm profitability under Kenyan smallholder farmer conditions. We collected data through a detailed household survey conducted in eight counties in Kenya representative of high, medium, and low productivity zones using a sample of 1094 smallholder farmers. Multi-nutrient fertilizers increased maize yields significantly (P < 0.05), eliciting a 400% yield increase compared to the control and 108% greater maize yield than conventional fertilizers in the high potential zone. Conversely, at 3.7 t/ha conventional fertilizers elicited a significant (P < 0.05) yield response in Irish potatoes in the high potential areas. Multi-nutrient fertilizers increased on-farm profitability of crops, specifically for potato production systems where a benefit: cost ratio (BCR) of more than 2 was observed. Farmers may break even when they use multi-nutrient fertilizers on maize particularly in the low potential areas. Therefore, there is considerable potential for multi-nutrient fertilizers to increase crop productivity while being economically viable across agroecological zones and cropping systems. However, the uptake of multi-nutrient fertilizers among farmers is quite low across the country, except for small pockets where limited interventions have been carried out. This calls for sustained efforts to scale multi-nutrient fertilizers with a focus on clear messaging that stresses the need to apply appropriate rates of various nutrients including the secondary nutrients and micro-nutrients.

Detrital U–Pb rutile and zircon data show Indus River sediment dominantly eroded from East Karakoram, not Nanga Parbat

Rapid uplift and exhumation is hypothesized to occur within focused zones of orogenic syntaxes which may dominate sediment flux from a mountain belt. The Namche Barwa-Gyala Peri Massif (NBGPM) in the Himalayan Eastern syntaxis is an example of such a high sediment production zone. Here we apply detrital zircon and rutile U–Pb dating to modern river sediments sampled up- and downstream of the Nanga Parbat-Haramosh Massif (NPHM) in the Western Himalayan syntaxis. Mass balancing of these data show that the total amount of sediment contributed to the trunk Indus from NPHM is relatively small, accounting for 9–10% of the total zircons reaching the Arabian Sea, and potentially much less when source fertility is taken into account. The sediment productivity of NPHM is high but likely less than half of that seen at NBGPM (30–56 Mt/yr vs. 72–211 Mt/yr). This discrepancy may be explicable by the drier climate, less prominent syntaxial knick-zone, and weaker spatial relationship between NPHM and the Indus River compared to its eastern twin. Our revised sediment flux estimate for NPHM implies regional modern exhumation rates of ∼3–5 mm/y, lower than estimated from the core massif since 1.7 Ma.

Delineation of nutrient management zones for precise fertilizer management in wheat crop using geo‐statistical techniques

AbstractUnderstanding the variability in crop yield in relation to the spatial variations in soil properties can help to more efficiently apply agricultural inputs on a site‐specific basis. This study was designed to characterize and quantify the spatial variation in soil properties and wheat yield and to delineate prescription maps for site‐specific fertilization. A wheat field was selected at the research farm of the University of Agriculture, Faisalabad, Pakistan, and a grid pattern (30 m * 30 m) was established at the experimental sites to collect soil and crop yield samples at two sampling depths (0–15 &amp; 15–30 cm). The soil samples were analysed for soil nitrogen (N), phosphorus (P), potassium (K), pH, electrical conductivity (EC), soil organic matter (SOM) and saturation (S) at both sampling depths. The locations of the sampling points and field boundary were marked with a GPS receiver. Results of classical, geo‐statistical and interpolated maps revealed significant spatial variability in soil properties and crop yield, demanding for site‐specific nutrient management. The cluster analysis was performed to group the soil and yield data into five productivity zones termed as ‘very low’, ‘low’, ‘medium’, ‘high’ and ‘very high’ without prior knowledge of productivity potential with the internal homogeneity and external heterogeneity at a similarity level of greater than 70%. Results of correlation matrix suggested significant relationships among the crop yield and the soil properties. Results of means comparison in different productivity zones indicated that the crop yield and soil properties were significantly different in developed management zones except ‘low’ and ‘very low’ zones. Significant variation of soil nutrients in very low‐to‐very high productivity zones at both sampling depths suggested that the soil nutrients in combination with soil pH and organic matter can be used to develop prescription maps for site‐specific fertilization. Furthermore, the results of this study emphasize the need to predict soil and crop variables using sensors, in future studies, to delineate prescription maps, as soil sampling and analysis is expansive and time consuming. Site‐specific fertilization based on soil and crop needs can improve economic and environmental efficiency.

Алюминий в кварце месторождения золота Дарасун (Восточное Забайкалье, Россия)

Quartz samples taken from the ore veins of the Darasun gold deposit (Eastern Transbaikalia, Russia) were studied using electron paramagnetic resonance (EPR) and laser ablation (LA) methods. The purpose of the research was to clarify the behavior of the Al impurity during quartz crystallization and its subsequent recrystallization. The results of the research were used to determine the genetic informativeness of the Al impurities concentration in ore quartz. A separate study of the regularities of the distribution of Al impurity in the regions of crystalline structure and in the zones of crystal lattice distortions was carried out. In the regions of crystalline structure, the Al impurity concentration NAL was determined by the concentration of paramagnetic Al–O–-centers associated with the presence of substitutional Al3+ ions. The content of the Al impurity in the zones of crystal lattice distortions was judged by the difference between the gross concentrations of aluminum CAl and the values of NAL. It was taken into account that the intensity and direction of the studied processes can be influenced by the temperature of quartz formation and the degree of its recrystallization. The temperature of quartz formation was estimated by the values of Ti impurity concentration, and the degree of recrystallization was estimated by the content of Li impurity CLi in the mineral. It was found that the amount of Al impurity localized in the zones of crystal lattice distortions is an order of magnitude higher than that present in the zones of crystalline structure. It is shown that this phenomenon is explained by the high ability of the zones of crystal lattice distortions to capture of Al impurity during quartz crystallization. The amount of Al impurity trapped by quartz increases sharply with an increase in the temperature of the mineral formation. In areas of regions of crystalline structure, a different picture is observed − impurity capture during crystallization proceeds with low intensity and is not so critically dependent on temperature. It was found that the Al impurity in the considered zones behaves differently during quartz recrystallization. If Al impurity capture continues in the regions of crystalline structure, then Al impurity removal from quartz can occur in the zones of crystal lattice distortions at high CAl values. Based on the data obtained, the areas of use of aluminum impurity contents as a typomorphic feature of ore quartz were determined. The Al impurity concentrations proved to be suitable for use in cases of low ore formation temperatures, and its gross CAl contents have the prospect of wider use. It is noted that a characteristic feature for quartz from high productivity zones is a negative angle of slope of the CAl(CLi) dependence plot.

Geographical and economic assessment of feedstock availability for biomass gasification in Burkina Faso

The crop production of Burkina Faso generates a large amount of residues that can be used for energy production. In the high crops production zone, people face low access to energy for household use and productive activities. Due to the widespread inefficient production and use of traditional energy sources, technologies as gasification have been implemented in rural areas for productive activities. One of the issues of implementing gasification in this country is the securing of biomass supply. This paper aims at assessing the availability of residues that could be used for gasification. Three levels of potential for plant and agro-industrial residues are estimated based on product-to-residue ratios and crop production. The results show that the theoretical agricultural residue pool is about 8 million tonnes. Sustainable recovery rates have been considered to protect soil fertility, human and animal consumption. Only cotton stalks and rice husks are recoverable at 75% and 20%. The mobilizable potential for bioenergy is 723,260 tonnes of cotton stalks and 6,497 tonnes of rice husks. These residues have an energy potential of 44,638 toe and 253 toe, respectively. The agricultural residues can therefore contribute sustainably to satisfy the bioenergy needs of the country's agro-industrial sector.

Analysis of fractures in the Dalan and Kangan carbonate reservoirs using FMI logs: Sefid-Zakhur gas field in the Fars Province, Iran

Fracture evaluation is very important in the carbonate reservoirs, particularly fractured reservoir, due to the high impact of fractures on the reservoir permeability. Assessment of fracture parameters of reservoirs is necessary to optimize oil production. Image logs are regarded the best methods for this aim. This study aims to use electrical image logs in the Dalan and Kangan Formations reservoir in the Zagros Basin, SW Iran. This paper presents the new findings of analysis of the effective structures on reservoir quality of the Dalan and Kangan Formations in one of the Iranian gas fields by using FMI image logs. Formation micro-imager (FMI) was taken along with petrophysical logs from depth 4677–5253. FMI data were processed and evaluated. Through this assessment, different types of natural structures such as the fracture (open, close) and bedding planes were identified. The data analysis presented different fracture sets that have a different orientation to the anticline axis. All identified bed contacts were used to determine the structural dip. The general structural dip is interpreted to be 40 degrees toward N15E, with a corresponding strike of N75W-S75E. The total fractures encountered are in three categories: major-conductive, medium-conductive, and minor-conductive fractures. Fracture apertures with values more than 0.01 cm can be the highest value of fracture aperture with a value of more than 0.1 cm, which can be observed at 5013–5015 m, 5023 m, and 5065–5070 m. The range of fracture porosity from conductive fractures is computed to be 0–0.6%. Fractures with porosity range of more than 0.4% can be observed at 4953–4960 m, 4966 m, 4973–4980 m, 5020 m, 5113 m, and 5153 m (Lower Dalan). The highest fracture porosity can be observed at 4954 and 5020 m (close to 0.6%). The main productive zones appear to be 5160–5110 m, 5030–5000 m, 4980–4910 m, and 4830–4770 m. In this section of the reservoir, the high density, porosity, and aperture of the natural conductive/open fractures at certain intervals may indicate high productivity zones at these particular places. Considering the conductive/open fracture apertures, a production profile for a reservoir can be predicted from the fracture-enhanced permeability, with the assumption that the production of the reservoir is fracture-controlled. With the same assumption for the reservoirs within the 5.875-in. section of the well, a predictive production profile was constructed by integrating the fracture apertures.

Variability of Net Primary Productivity and Associated Biophysical Drivers in Bahía de La Paz (Mexico)

The use of information of net primary productivity (NPP) from remote ocean color sensors is increasingly common in marine sciences. The resulting information has been used to explain variations in productivity at different spatio-temporal scales and in the presence of climate phenomena, such as the El Niño Southern Oscillation, and global warming. Satellite remote sensing data were analyzed in Bahía de La Paz (BLP), Mexico, to determine the spatio-temporal variation in NPP. In addition, in situ hydrographic data were obtained to characterize the water properties in the bay. The satellite data agree with in situ measurements, validating the satellite observations over this region. The NPP generally presented seasonal variation with maximum values in winter-spring and minimum values in summer–autumn. The variance explained by NPP from the measured variables was ranked as Chl-a &lt; DEN &lt; SST &lt; PAR &lt; WSC. The highest NPP values generally occurred when subtropical subsurface (SsStW) water was relatively shallow. Due to divergence and mixing processes, this water provided nutrients to the euphotic zone, and consequently an increase in NPP and changes in plankton biomass were observed. The annual trends of the variation in hydrographic data with respect to that of remote sensing data were similar; however, it is necessary to increase the number of data validation studies. The remote sensing and in situ measurements allowed for the main biophysical variables that modulate NPP in different time scales to be identified. The satellite-derived NPP data classifies the BLP as a high productivity zone with 432 g C m−2 year−1. The use of satellite NPP data is satisfactory and should be incorporated into marine primary productivity studies.

Satellite-based observation of ocean productivity in southeast Arabian Sea using chlorophyll, sea surface temperature and wind datasets

The phytoplankton variability and ocean productivity have been studied with the retrieval of chlorophyll concentration (CC) from various satellite ocean colour missions. The phytoplankton distribution is related to ocean processes and physical parameters such as temperature, wind speed, currents, etc., at regional and global scales. In the current study, the phytoplankton productivity has been observed in the southeast Arabian Sea during southwest (SW, June–September) and northeast (NE, October–December) monsoon seasons using merged chlorophyll product datasets during the years 2017 and 2018. There has been an observation of high chlorophyll concentration (~5.0 mg m−3) in the southeast Arabian Sea (southern tip of India) during SW monsoon and less in NE monsoons (~1.0 mg m−3). The spread in CC has been observed maximum during July–September. High anomaly of CC was observed along north-eastern Arabian Sea during northeast monsoon months of 2017 due to the very severe cyclonic storm Ockhi. Similarly, during August 2018, high chlorophyll concentration was observed (18.8 mg m−3) in south-eastern tip as a result of heavy rainfall and discharge of nutrient rich riverine water. The sea surface temperature (Modis-Aqua SST) has been observed to be cooler (26–27°C) in the SE Arabian Sea coastal waters during July–August as compared to warmer (28–30°C) surrounding waters. During the SW monsoon (June–August), the wind speed has been observed to be of high magnitude (~10 m/s), which was not evident during September. The alongshore (north-westerly) wind has been observed during July–September in the near coastal water that causes coastal to offshore moving Ekman mass transport (EMT). Similarly, the alongshore (north-easterly) wind has been observed during December in the southern tip of India and off Sri Lankan west coast. The strong zonal EMT (–1500 to –500 kg/m/s) has been observed in the southeast Arabian Sea during July–September 2017 and 2018 which is weak to moderate (> –500 kg/m/s) in NE monsoon months. Statistical analysis has been made between SST, wind speed and CC which shows significant correlation coefficient (r > 0.6, p < 0.001). Hence, the present study confers that the alongshore wind and high wind speed regions are favourable to upwelling events and have been responsible for cooling of SST resulting in high productivity zones in the southeast Arabian Sea, which is important from the point of view of marine fishery and ecosystem assessment.

Representative Sector Modeling and Waterflooding Performance in Rumaila Oilfield

Rumaila supergiant oilfield, located in Southern Iraq has a huge footprint and is considered as the second largest oilfield in the world. It contains many productive reservoirs, some known but without produced zones, and significant exploration potential. A fault divides the field into two domes to the north and south. Mishrif reservoir is the main producing reservoir in the North Rumaila oilfield. It has been producing for more than 40 years and is under depletion. However, it was subjected to water injection processes in 2015, which assisted in recovery and pressure support. Thus, requirements of managing flooding strategies and water-cut limitations are necessary in the next stages of the field life.&#x0D; In this paper, sector modeling was applied to a specific portion of the field, rather than full-field modeling, to accelerate history matching strategy and correlate static to dynamic models’ efficiently, with a minimum level of tolerance. The sector was modeled by surrounding with additional grid blocks and two pseudo wells to achieve a good matching with actual available data.&#x0D; PVT data were used for fluid modeling of a well contained in the sector, and two rock functions were inserted to the model to achieve acceptable history matching. Twelve wells were considered in this research, two of them were injectors and the remaining are producers. For future performance, some of these wells were subjected to new completion and workover processes for field development and pressure maintenance. The importance of the development plan is to represent a way for field development without new wells to be drilled. This was conducted by adding perforations to some wells, plugging the high water-cut production zones, changing production and injection rates, and converting the producers to injectors.

Recent Ostracoda from the shelf sediments of Southwestern part of Bay of Bengal: Implication on Microenvironments

A detailed study on Recent Ostracoda was carried out in twenty-six surface sediment samples collected from shelf region of the Southwestern part of Bay of Bengal. A total of 21 species of Ostracoda belonging to 18 genera have been identified, of which, seven species are abundant (>5%). The Q-mode and R-mode cluster analyses of the abundant species resulted in two assemblage defining different microenvironments. The shallowest assemblage (I) from 10 to 80 m water depth is characterised by Hemikrithe Orientalis, Pterygocythereis chennaiensis and Lankacythere multifora which are associated with sand to slightly muddy sand. The second assemblage (II) from 80 to 200 m water depth is associated by Keijella reticulata, Bairdoppilata paraalcyonicola, Actinocythereis scutigera and Stigmatocythere indica and the nature of sediments varies from slightly muddy sand to slightly sandy mud. The sediments from 50-100 m water depth are foundto contain higher concentration of organic matter (TOC and TN) suggesting the high productivity zone. The C/N ratio value ranges from 4 to 8 in 52% of sediment samples indicating both marine and terrestrial source. The shallower part of the seafloor up to 30 m depth is dominated by sandysediments, reflecting the occurence of high-energy conditions. The higher mud content in the deeper part is due to the prevalance of low energy condition. The carapace-valve ratio (1:9) indicates that the study area experiencing a slower rate of sedimentation. Our study results revealed that the distribution of Ostracoda in the Southwestern part of Bay of Bengal is controlled by the type of sediment, depth and physicochemical parameters of the bottom water.

Cocoa Production and Forest Dynamics in Ivory Coast from 1985 to 2019

The cocoa economy of Ivory Coast started in the eastern part of the country in the 1970s and spread to the central-western and then south-western regions. For nearly a decade, it has been in the West of Ivory Coast with a population increase caused by large waves of migration. This study aims to determine different factors explaining dynamics of the cocoa economy from the East to West of Ivory Coast. The method adopted consisted of processing Landsat images from 1985–2018 and an individual survey of 278 heads of households. The results obtained showed that the development of the cocoa economy led forest cover degradation with a total loss estimated at 60.80%, 46.39%, 20.76% and 51.18% of forest area in the East, Centre-West, South-West and West, respectively. The creation of new cocoa farms in the West of Ivory Coast is governed by non-native people (51.13%) settled between 2010 and 2018. About 41% of these producers come mainly from the Centre-West (25%) and the South-West (16%). In addition, 29% of producers come from the West of Ivory Coast. Despite the abiotic characteristics being considered unfavourable, the west of Ivory Coast is in the process of becoming the country’s new zone of high cocoa production.

Geochemical Features of Redox-Sensitive Trace Metals in Sediments under Oxygen-Depleted Marine Environments

Organic- and sulfide-rich sediments have formed in oxygen-depleted environments throughout Earth’s history. The fact that they are generally enriched in redox-sensitive elements reflects the sedimentary environment at the time of deposition. Although the modern ocean is well oxidized, oxygen depletion occurs in certain areas such as restricted basins and high-productivity zones. We measured bulk chemical compositions (major and trace elements, total organic carbon, and total sulfur) of organic- and sulfide-rich sediments collected from eight areas having oxygen-depleted water to discuss relationships between geochemical features and sedimentary environments. Major elemental compositions generally show mixtures of terrigenous detritus and biogenic carbonate. Some redox-sensitive elements might be controlled by organic matter content, whereas others could be contained in sulfide minerals in sediments. In particular, Mo and U show a characteristic trend; areas with higher Mo and U—at least partially owing to a depositional process called the “particulate shuttle”—generally correspond to regions influenced by the open ocean. In contrast, areas with lower Mo and U are more restricted marine environments. This suggests that the degree of Mo and U enrichment reflects the geography in terms of proximity to the open ocean, or the degree of the supply of these elements from the open ocean.

Development of a Polyacrylamide-Based Mud Formulation for Loss Circulation Treatments

Abstract Loss circulation materials in the last two decades have witnessed a lot of developments and implementations. New technologies and materials are introduced to treat various types of loss zones. However, the success rate is still very low due to many uncertainties in the selection of types and particle size of the bridging materials. In addition, there are many operational restrictions such as the risk of plugging and pumping difficulties when large size of particle is needed, especially in deep-water drilling. In this study, polyacrylamide (PAM) crosslinked with polyethylenimine (PEI) is introduced as polymer-based mud for loss circulation treatment. The PAM/PEI systems have wide applications in water shutoff for high water production zones and are known for their strong gel and exceptional rheological properties. This study provides a rheological method for screening of PAM/PEI-based drilling formulation with optimized molecular weight and concentrations. Comparative analysis of rheology of non-crosslinked and crosslinked polyacrylamide with other drilling fluids additives as well as proper mixing procedures are provided. The results achieved in this study are used as a strong tool to design a polymer-based mud with competitive rheological properties which achieved an 80% reduction in fluid loss when compared with other conventional loss circulation materials.

Variable Rate Nitrogen and Water Management for Irrigated Maize in the Western US

Nitrogen (N) and water continue to be the most limiting factors for profitable maize (Zea Mays L.) production in the western US Great Plains. Precision application of N and water has the potential to significantly enhance input use efficiency without impairing yields. The overall objective of this study was to determine the most productive and efficient nitrogen and water management strategy for irrigated maize by using site-specific management zones and a proximal remote sensing approach. This study was conducted over 2016, 2017, 2018 and 2019 crop growing seasons near Fort Collins, Colorado, USA. Six nitrogen rates (0, 56, 112, 168, 224, and 280 kg N ha−1) were applied along experimental strips across three delineated management zones (low, medium, and high productivity). Four rates of irrigation were applied to maize (60%, 80%, 100%, and 120% of evapotranspiration) using a center pivot precision irrigation system equipped with zone control. Optical proximal sensor readings were acquired on all experimental strips four times during the growing season to assess four nitrogen management strategies (uniform, management zone (MZ), remote sensing (RS), and management zone remote sensing (MZRS)) on grain yield and nitrogen use efficiency (NUE). Results from this three-year study showed the significant interaction (p = 0.05) of zone vs. irrigation and irrigation vs. nitrogen across all years. In two of the three years (2016 and 2018), the high productivity zone benefitted from high irrigation rates, demonstrated by 16% and 18% yield increase from the lowest irrigation rate. In 2016, yield plateau was reached at 168 kg N ha−1 with 80% and 100% irrigation rates, whereas the plateau was reached at 112 kg N ha−1 in the 120% irrigation rate. These results demonstrate the possibility of fine-tuning zones, irrigation, and nitrogen to achieve optimum yield. While uniform and MZ nitrogen management strategies produced the highest grain yield, the best NUE was achieved via the RS strategy, followed by the MZ strategy. In this study, the MZRS strategy (combined MZ and RS) did not produce superior yield and NUE as compared to uniform and other strategies. However, there is a tremendous opportunity to fine-tune these two strategies, using other algorithms that are not explored in this study to improve the sustainability of maize production under irrigated conditions.