The effect of wetting pre-treatment on the desorption moisture characteristic of vertisols

Soil Research ◽  
1989 ◽  
Vol 27 (1) ◽  
pp. 27 ◽  
Author(s):  
PJ Thorburn ◽  
EA Gardner ◽  
AF Geritz ◽  
KJ Coughlan
Keyword(s):  
Soil Depth ◽  
Clay Fraction ◽  
Field Studies ◽  
Small Water ◽  
Wide Range ◽  
Additional Water ◽  
Moisture Characteristic ◽  
Pre Treatment ◽  
Reduced Rate ◽  
Maximum Field

Four experiments were conducted by using individual aggregates and ground samples of different soils and a range of wetting pre-treatments to investigate the effect of wetting on the desorption moisture characteristic of Vertisols. Wetting rate was varied by manipulating the energy of the water used to wet up the soil. Fast wetting was found to increase moisture uptake in Vertisols over a wide range of matric potentials (to -38 MPa in one soil). At high matric potentials, additional water uptake ranged up to 0.26 g g-l. These results were attributed to the creation of planar voids within soils between small water-stable aggregates on fast wetting. These voids retained water at matric potentials as low as -90 kPa. At this potential, 40% of additional water taken up on fast wetting was still retained in one soil. At -1500 kPa, fast wet soils retained up to 1.2 times more moisture relative to slow wet soils. The effect of wetting at potentials of -1500 kPa and less appeared to be related to the smectite content of the soil clay fraction and the degree of order of clay quasi-crystals. The soil which showed the greatest effect of fast wetting at these potentials had a less well ordered clay micro-structure. These findings have relevance to field studies, as variations in maximum field soil moisture content, with depth, could be reproduced by tension wetting pre-treatments. This result indicates that reduced rate of subsoil wetting may be responsible for the decrease in maximum field water contents with increasing soil depth, which has been observed in Vertisols. Such profiles have previously been attributed to the effect of overburden and stress potentials alone.

scholarly journals Effects of Light, Temperature, and Soil Depth on the Germination and Emergence of Conyza canadensis (L.) Cronq.

Agronomy ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 533 ◽  
Author(s):  
Daniele Ottavini ◽  
Euro Pannacci ◽  
Andrea Onofri ◽  
Francesco Tei ◽  
Peter Kryger Jensen
Keyword(s):  
Invasive Species ◽  
Soil Depth ◽  
Global Climate ◽  
Conyza Canadensis ◽  
Base Temperature ◽  
Complete Darkness ◽  
Water Imbibition ◽  
Ceiling Temperature ◽  
Wide Range ◽  
Pre Treatment

Understanding the dynamics of invasive species under global climate change requires knowledge about the effects of environmental factors on germination and emergence. We considered Conyza canadensis (L.) Cronq., an invasive species that is quickly invading Southern European agricultural systems, and performed germination assays in growth chambers at eight constant temperatures with alternating light (2.5, 5, 10, 15, 20, 25, 30, and 40 °C, with 12 h/12 h—light/dark), three alternating temperatures in alternating light (12/18, 17/23, and 22/28 °C, with 12 h/12 h—light/dark) and three fixed temperatures (15, 20, and 25 °C) in complete darkness. Furthermore, emergence assays were performed in pots considering four depths (0, 2.5, 5, and 10 mm), three temperatures with alternating light (15, 20, and 25 °C) and un-treated or pre-treated seeds (water imbibition and light for two days). C. canadensis was able to germinate in a wide range of temperatures (from 5–10 °C to 30 °C). The highest germination capacity was observed at 15 °C (light/dark); no differences were observed at 17/23 and 22/28 °C with respect to 20 and 25 °C (light/dark), while germinations were significantly reduced at 12/18 °C. The lowest germination time was observed at 25 °C (light/dark) and it was significantly increased at 12/18 °C and in darkness. The highest emergence was from 0 mm depth; pre-treatment significantly increased the emergence from 2.5 mm and 5 mm depth, but not from 10 mm depth. Modeling germination rates as a function of temperature allowed us to determine Tb = 6.8 °C (base temperature) and Tc = 35.8 °C (ceiling temperature). In light of these results, the potential for C. canadensis to spread into new environments and possible new management methods are discussed.

scholarly journals Prediction of leaching and groundwater contamination by pesticides

2006 ◽  
Vol 78 (5) ◽  
pp. 1081-1090 ◽  
Author(s):  
Werner Kördel ◽  
Michael Klein
Keyword(s):  
Maximum Concentration ◽  
Management Practices ◽  
Preferential Flow ◽  
Soil Depth ◽  
Sandy Soils ◽  
Field Studies ◽  
Macropore Flow ◽  
Eu Directive ◽  
Present Information ◽  
Silty Soils

Herein, we describe how pesticide leaching is assessed in Europe in order to fulfill EU Directive 91/414. The assessment schemes were developed to protect groundwater from unacceptable effects caused by pesticide use. They presently focus on chromatographic flow processes, which are dominant in sandy soils. Nevertheless, important regions in Europe are characterized by structured soils where transport through macropores is most relevant.Comparison of parallel field studies with isoproturon performed in sandy and silty soils showed that maximum concentration in the structured soil at a soil depth of 1 m may exceed respective concentrations in sandy soils by a factor of 60. Similar results were obtained by lysimeter studies using silty soil cores with maximum concentration of 40 μg/l at the soil bottom. These results demonstrate that preferential flow is more the rule than the exception in well-structured fine-textured soils, and pesticide losses via macropore flow may exceed losses via matrix transport considerably. All present information available for macropore flow suggest the need for greater regional assessments. Other recommendations include analysis of the influence of different soil management practices on the formation of macropores.

BIODIVERSITI DAN PEMULIHARAAN TERUMBU KARANG DI TIGA BUAH PULAU, MELAKA (Biodiversity and Conservation of Coral Reefs in Three Islands in Malacca)

2021 ◽  
Vol 22 (1) ◽  
pp. 180-197
Author(s):  
SYAIMAK ISMAIL ◽  
MOHAMAD SAUPI BIN ISMAIL ◽  
MUHAMMAD SAIFUL ISLAM ISMAIL ◽  
AEMY AZIZ
Keyword(s):  
Coral Reefs ◽  
Biodiversity Conservation ◽  
Soft Coral ◽  
Good Condition ◽  
Scuba Diving ◽  
Field Studies ◽  
The State ◽  
Hard Coral ◽  
Wide Range ◽  
State Museum

In the state of Melaka, there are eighteen islands recorded by the Melaka State Museum Corporation (PERZIM). Part of this island serves as a tourist island, and developed islands are also uninhabited islands. However, three islands are recorded to have amazing coral reefs that are still in good condition. The Penang Batu Maung Fisheries Research Institute (AkuaTAR) has conducted a study on the biodiversity of coral reefs around the waters of Pulau Dodol, Pulau Serimbun, and Pulau Undan. AkuaTAR researchers are using scuba diving methods, and at the same time, they did conservation on coral reefs that have been identified in the waters of the Straits of Melaka. The objective of this study is to record the types of community forms such as living corals and identify the species of coral reefs found in three islands in the state of Melaka in Pulau Undan, Pulau Dodol, and Pulau Serimbun. The study also implemented method observation by conducting field studies on the islands involved by doing scuba diving. Results and discussion of the search, these three islands are located in very clean, uninhabited waters. They have a wide range of coral biodiversity using soft coral reefs and hard coral reefs. The study also found that the three islands in the state have the largest coral reefs in the waters of the Straits of Melaka. Keywords: Biodiversity; Conservation; Coral; Three island; Melaka

scholarly journals Wintertime aerosol chemical composition, volatility, and spatial variability in the greater London area

2016 ◽  
Vol 16 (2) ◽  
pp. 1139-1160 ◽  
Author(s):  
L. Xu ◽  
L. R. Williams ◽  
D. E. Young ◽  
J. D. Allan ◽  
H. Coe ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Solid Fuel ◽  
Field Studies ◽  
Rural Site ◽  
Urban Site ◽  
High Temporal Resolution ◽  
Volatile Organics ◽  
Aerosol Mass ◽  
Rural And Urban ◽  
Wide Range

Abstract. The composition of PM1 (particulate matter with diameter less than 1 µm) in the greater London area was characterized during the Clean Air for London (ClearfLo) project in winter 2012. Two high-resolution time-of-flight aerosol mass spectrometers (HR-ToF-AMS) were deployed at a rural site (Detling, Kent) and an urban site (North Kensington, London). The simultaneous and high-temporal resolution measurements at the two sites provide a unique opportunity to investigate the spatial distribution of PM1. We find that the organic aerosol (OA) concentration is comparable between the rural and urban sites, but the contribution from different sources is distinctly different between the two sites. The concentration of solid fuel OA at the urban site is about twice as high as at the rural site, due to elevated domestic heating in the urban area. While the concentrations of oxygenated OA (OOA) are well-correlated between the two sites, the OOA concentration at the rural site is almost twice that of the urban site. At the rural site, more than 70 % of the carbon in OOA is estimated to be non-fossil, which suggests that OOA is likely related to aged biomass burning considering the small amount of biogenic SOA in winter. Thus, it is possible that the biomass burning OA contributes a larger fraction of ambient OA in wintertime than what previous field studies have suggested. A suite of instruments was deployed downstream of a thermal denuder (TD) to investigate the volatility of PM1 species at the rural Detling site. After heating at 250 °C in the TD, 40 % of the residual mass is OA, indicating the presence of non-volatile organics in the aerosol. Although the OA associated with refractory black carbon (rBC; measured by a soot-particle aerosol mass spectrometer) only accounts for < 10 % of the total OA (measured by a HR-ToF-AMS) at 250 °C, the two measurements are well-correlated, suggesting that the non-volatile organics have similar sources or have undergone similar chemical processing as rBC in the atmosphere. Although the atomic O : C ratio of OOA is substantially larger than that of solid fuel OA and hydrocarbon-like OA, these three factors have similar volatility, which is inferred from the change in mass concentration after heating at 120 °C. Finally, we discuss the relationship between the mass fraction remaining (MFR) of OA after heating in the TD and atomic O : C of OA and find that particles with a wide range of O : C could have similar MFR after heating. This analysis emphasizes the importance of understanding the distribution of volatility and O : C in bulk OA.

scholarly journals Efficacy of Synthetic Pesticides Against Thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae) on Okra Abelmoschus esculentus (L.) Moench

2021 ◽  
Vol 13 (9) ◽  
pp. 148
Author(s):  
Hira Mannan ◽  
Qurban Ali Nahiyoon ◽  
Jilian Li
Keyword(s):  
Insect Pests ◽  
Thrips Tabaci ◽  
Abelmoschus Esculentus ◽  
Vegetable Crops ◽  
Vegetable Crop ◽  
Agronomic Crops ◽  
Wide Range ◽  
Field Efficacy ◽  
Synthetic Pesticides ◽  
Pre Treatment

Okra (Abelmoschus esculentus L.) is an essential vegetable crop with good nutritional significance. Insect pests are the major threat for poor production of the okra crop. Thrips of vegetable crops are known to be serious pests on a wide range of fruit, vegetable, flower, and agronomic crops. The present field study was carried out to know the efficacy of different insecticides (acetamiprid 19% weightable water (ww), lambda 25% ww, colarphipare 32% ww, lambda 2.5% ww and abamectin 1.3% ww) against Thrips, Thrips tabaci (Lindeman) on okra crop during the year 2019, and observations against T. tabaci (Lindeman) were recorded after 24 hrs, 48 hrs, 72 hrs and 07 days of each spray in all the treatments. The pre-treatment count of thrips on okra was non-significant (P &gt; 0.05); while the evaluated efficacy of different insecticides against thrips was significant (P &lt; 0.01). It was noted that all the insecticides showed their highest efficacy after 7 days of spray and acetamiprid 19% weightable water (ww) was more efficient to combat the T. tabaci as compared to other pesticides that produced field efficacy of 73.92 and 74.91% against thrips after 7 days of 1st and 2nd spray respectively. Abamectin, 1.3% ww, was reasonably successful, yielding 53.81 and 56.66% field efficacy against T. tabaci (Lindeman) after 7 days of first and second spray. Also, moderately effective was colarphipare 32% ww, which developed field effectiveness of 56.41 and 61.49% against T. tabaci (Lindeman) after 7 days of first and second spray, respectively.

scholarly journals Emission of nitrous acid from soil and biological soil crusts represents an important source of HONO in the remote atmosphere in Cyprus

2018 ◽  
Vol 18 (2) ◽  
pp. 799-813 ◽  
Author(s):  
Hannah Meusel ◽  
Alexandra Tamm ◽  
Uwe Kuhn ◽  
Dianming Wu ◽  
Anna Lena Leifke ◽  
...  
Keyword(s):  
Nitrous Acid ◽  
Biological Soil Crust ◽  
Ground Surface ◽  
Field Studies ◽  
Bare Soil ◽  
Biological Soil Crusts ◽  
Soil Crusts ◽  
Wide Range ◽  
Mediterranean Island ◽  
Water Holding

Abstract. Soil and biological soil crusts can emit nitrous acid (HONO) and nitric oxide (NO). The terrestrial ground surface in arid and semiarid regions is anticipated to play an important role in the local atmospheric HONO budget, deemed to represent one of the unaccounted-for HONO sources frequently observed in field studies. In this study HONO and NO emissions from a representative variety of soil and biological soil crust samples from the Mediterranean island Cyprus were investigated under controlled laboratory conditions. A wide range of fluxes was observed, ranging from 0.6 to 264 ng m−2 s−1 HONO-N at optimal soil water content (20–30 % of water holding capacity, WHC). Maximum NO-N fluxes at this WHC were lower (0.8–121 ng m−2 s−1). The highest emissions of both reactive nitrogen species were found from bare soil, followed by light and dark cyanobacteria-dominated biological soil crusts (biocrusts), correlating well with the sample nutrient levels (nitrite and nitrate). Extrapolations of lab-based HONO emission studies agree well with the unaccounted-for HONO source derived previously for the extensive CYPHEX field campaign, i.e., emissions from soil and biocrusts may essentially close the Cyprus HONO budget.

Sicklepod (Cassia obtusifolia) and Coffee Senna (Cassia occidentalis): Geographic Distribution, Germination, and Emergence

Weed Science ◽  
1980 ◽  
Vol 28 (1) ◽  
pp. 68-71 ◽  
Author(s):  
D. H. Teem ◽  
C. S. Hoveland ◽  
G. A. Buchanan
Keyword(s):  
United States ◽  
Sulfuric Acid ◽  
Geographic Distribution ◽  
Soil Depth ◽  
The United States ◽  
Cassia Obtusifolia ◽  
Cassia Occidentalis ◽  
Southern States ◽  
Germination Characteristics ◽  
Wide Range

The distribution of sicklepod (Cassia obtusifoliaL.) and coffee senna (Cassia occidentalisL.) in the United States is similar and both species are increasing as problems within their range. Sicklepod is a problem in 11 southern states and increasing in 12 while coffee senna is a problem in 7 states and increasing in 8 states. Both species germinated over a wide range of temperature. Germination characteristics were similar in the range of 15 to 36 C. Germination of coffee senna was drastically reduced at 39 C byRhizopussp. Seedling growth was similar for both species and was maximum from 30 to 36 C. Both species have a hard seedcoat. Abrasion for 5, 10, or 15 s, puncturing with a needle, and sulfuric acid were all effective in initiating germination. Both species emerged from a soil depth of 12.5 cm; however, emergence of sicklepod was more rapid than coffee senna with 63% of the sicklepod seedlings emerging from 2.5 cm after only 3 days.

Remote Sensing of Surface Water Dynamics Between 2015 and 2020 in the Prairie Pothole Region 

2021 ◽  
Author(s):  
Stefan Schlaffer ◽  
Marco Chini ◽  
Wouter Dorigo
Keyword(s):  
Surface Water ◽  
Prairie Pothole Region ◽  
Water Area ◽  
Water Bodies ◽  
Water Dynamics ◽  
Drought Indices ◽  
Prairie Pothole ◽  
Small Water ◽  
Wide Range ◽  
Small Water Bodies

&lt;p&gt;The North American Prairie Pothole Region (PPR) consists of millions of wetlands and holds great importance for biodiversity, water storage and flood management. The wetlands cover a wide range of sizes from a few square metres to several square kilometres. Prairie hydrology is greatly influenced by the threshold behaviour of potholes leading to spilling as well as merging of adjacent wetlands. The knowledge of seasonal and inter-annual surface water dynamics in the PPR is critical for understanding this behaviour of connected and isolated wetlands. Synthetic aperture radar (SAR) sensors, e.g. used by the Copernicus Sentinel-1 mission, have great potential to provide high-accuracy wetland extent maps even when cloud cover is present. We derived water extent during the ice-free months May to October from 2015 to 2020 by fusing dual-polarised Sentinel-1 backscatter data with topographical information. The approach was applied to a prairie catchment in North Dakota. Total water area, number of water bodies and median area per water body were computed from the time series of water extent maps. Surface water dynamics showed strong seasonal dynamics especially in the case of small water bodies (&lt;&amp;#160;1&amp;#160;ha) with a decrease in water area and number of small water bodies from spring throughout summer when evaporation rates in the PPR are typically high. Larger water bodies showed a more stable behaviour during most years. Inter-annual dynamics were strongly related to drought indices based on climate data, such as the Palmer Drought Severity Index. During the extremely wet period of late 2019 to 2020, the dynamics of both small and large water bodies changed markedly. While a larger number of small water bodies was encountered, which remained stable throughout the wet period, also the area of larger water bodies increased, partly due to merging of smaller adjacent water bodies. The results demonstrate the potential of Sentinel-1 data for long-term monitoring of prairie wetlands while limitations exist due to the rather low temporal resolution of 12 days over the PPR.&lt;/p&gt;

Nausea and vomiting

2019 ◽  
pp. 531-538
Keyword(s):  
Treatment Algorithm ◽  
Nausea And Vomiting ◽  
Evidence Based ◽  
Nursing Management ◽  
Pharmacological Management ◽  
Chemotherapy Drugs ◽  
Wide Range ◽  
Detailed Assessment ◽  
Anticipatory Nausea And Vomiting ◽  
Pre Treatment

Nausea and vomiting are common and distressing symptoms of cancer and its treatments. Treatment-related nausea and vomiting are covered in depth, including pre-treatment assessment, the emetogenic level of chemotherapy drugs, and pharmacological management of chemotherapy-induced nausea and vomiting. An evidence-based treatment algorithm is described, covering the wide range of possible anti-emetics. Non-pharmacological options are also described. There is also a section on anticipatory nausea and vomiting. Nausea and vomiting in advanced cancer are covered separately. The multifactorial nature of this is discussed, with a focus on different anti-emetic regimes, as well as nursing management, including detailed assessment and ongoing nutritional and psychological support.

scholarly journals Emission of nitrous acid from soil and biological soil crusts represents a dominant source of HONO in the remote atmosphere in Cyprus

2017 ◽  
Author(s):  
Hannah Meusel ◽  
Alexandra Tamm ◽  
Uwe Kuhn ◽  
Dianming Wu ◽  
Anna Lena Leifke ◽  
...  
Keyword(s):  
Nitrous Acid ◽  
Biological Soil Crust ◽  
Ground Surface ◽  
Field Studies ◽  
Bare Soil ◽  
Biological Soil Crusts ◽  
Soil Crusts ◽  
Wide Range ◽  
Mediterranean Island ◽  
Water Holding

Abstract. Soil and biological soil crusts can emit nitrous acid (HONO) and nitric oxide (NO). The terrestrial ground surface in arid and semi-arid regions is anticipated to play an important role in the local atmospheric HONO budget, deemed to represent one of the unaccounted HONO sources frequently observed in field studies. In this study HONO and NO emissions from a representative variety of soil and biological soil crust samples from the Mediterranean island Cyprus were investigated under controlled laboratory conditions. A wide range of fluxes was observed, ranging from 0.6 to 264 ng m−2 s−1 HONO-N at optimal soil water content (20–30 % of water holding capacity, WHC). Maximum NO-N at this WHC fluxes were lower (0.8–121 ng m−2 s−1). Highest emissions of both reactive nitrogen species were found from bare soil, followed by light and dark cyanobacteria-dominated biological soil crusts (biocrusts), correlating well with the sample nutrient levels (nitrite and nitrate). Extrapolations of lab-based HONO emission studies agree well with the unaccounted HONO source derived previously for the extensive CYPHEX field campaign, i.e., emissions from soil and biocrusts may essentially close the Cyprus HONO budget.

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