scholarly journals Considering Soil Potassium Pools with Dissimilar Plant Availability

2020 ◽  
pp. 163-190
Author(s):  
Michael J. Bell ◽  
Michel D. Ransom ◽  
Michael L. Thompson ◽  
Philippe Hinsinger ◽  
Angela M. Florence ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Reaction Products ◽  
Waste Products ◽  
Secondary Minerals ◽  
Exchangeable K ◽  
Testing Procedures ◽  
Soil Potassium ◽  
Pool Model ◽  
Fertilizer Reaction Products ◽  
Primary Minerals

AbstractSoil potassium (K) has traditionally been portrayed as residing in four functional pools: solution K, exchangeable K, interlayer (sometimes referred to as “fixed” or “nonexchangeable”) K, and structural K in primary minerals. However, this four-pool model and associated terminology have created confusion in understanding the dynamics of K supply to plants and the fate of K returned to the soil in fertilizers, residues, or waste products. This chapter presents an alternative framework to depict soil K pools. The framework distinguishes between micas and feldspars as K-bearing primary minerals, based on the presence of K in interlayer positions or three-dimensional framework structures, respectively; identifies a pool of K in neoformed secondary minerals that can include fertilizer reaction products; and replaces the “exchangeable” K pool with a pool defined as “surface-adsorbed” K, identifying where the K is located and the mechanism by which it is held rather than identification based on particular soil testing procedures. In this chapter, we discuss these K pools and their behavior in relation to plant K acquisition and soil K dynamics.

Micronutrients

1999 ◽  
Author(s):  
Robert F. Keefer
Keyword(s):  
Plant Growth ◽  
Plant Tissue ◽  
Internal Drainage ◽  
Secondary Minerals ◽  
Soil Particles ◽  
Ring Compounds ◽  
Poorly Drained Soils ◽  
Iron Manganese ◽  
Primary Minerals ◽  
Growth And Reproduction

Micronutrients needed by plants are Cu, Fe, Mn, Zn, B, Mo, Cl, Ni, Co, V, Si, and Na. The required amounts of each of these elements is very small but still essential for desirable plant growth and reproduction. These elements must be applied to soils cautiously for the range between deficient and toxic is very small. It is unwise to use a fertilizer containing all of these micronutrients. Any one of them may already be high enough in soils to cause toxicity from that particular element. If a micronutrient is suspected of being deficient, it would be wise to get soil tests and plant tissue tests to corroborate your suspicions. If a micronutrient is deficient, one should apply only the amount recommended but no more. Sometimes a toxicity of an element is more difficult to correct than a deficiency. Copper, iron, manganese, cobalt, and zinc can be present in soils as (a) several types of precipitates, (b) adsorbed onto the surface of soil particles, (c) present in primary minerals (rocks) and secondary minerals (clays), and (d) present as complex ring compounds. These forms may or may not be available to plants. Precipitates of Cu, Fe, Mn, or Zn often form in soils at high pH (after liming Fig. 14.1). This may occur in soils near buildings from the lime used in the mortar. Soil acids dissolve the lime into Ca++ or Mg++ that migrate into the soil raising the pH and cause these micronutrients to precipitate. Often an Fe deficiency is evident, particularly on acid-loving plants, such as azaleas, rhododendrons, or hollies. If this is extensive, the soil near the buildings may need to be replaced. With limited areas, the soil can be acidified by adding elemental S near the plants affected. The elements Cu, Fe, Mn, and Zn can exist as soluble forms or precipitates, depending on the pH of the soil. The soluble forms as cations are present when soils have poor internal drainage (poorly drained soils), whereas the oxides of these elements are present where the soil is well aerated.

Testing Procedures on Materials to Formulate the Ink for 3D Printing

2020 ◽  
Vol 2674 (2) ◽  
pp. 21-32 ◽  
Author(s):  
Malo Charrier ◽  
Claudiane Ouellet-Plamondon
Keyword(s):  
3D Printing ◽  
Yield Stress ◽  
Three Dimensional ◽  
Testing Procedure ◽  
Full Potential ◽  
Cement Pastes ◽  
Slump Test ◽  
Testing Procedures ◽  
Transportation Sector ◽  
Printing Ink

Three-dimensional (3D) printing has been used in various fields to tackle applications difficult for conventional manufacturing. To realize the full potential of this technology in the transportation sector, it is imperative to identify suitable tests and mixtures for printing “inks” made of mortar. In this study, several conventional and non-conventional tests on mortars and cement pastes were conducted. This work highlights the correlation between the results of slump test and the deformation test that indicates the comportment of the mixture under a stack of printed layers. Moreover, a strong connection between yield stress and mini-slump is observed, demonstrating a simplification of the testing procedure, and a link between the mortar and the cement paste is developed. In the printing ink design phase, this association enables the prediction of flowability. The yield stress and the final radius of the mini-slump tests were very well correlated for the admixture tested. The use of the mini-slump test simplifies the testing procedure and allows for quicker formulations of admixtures in the printing ink.

TMI (Too much information)! Effects of given information on organic chemistry students’ approaches to solving mechanism tasks

2019 ◽  
Vol 20 (1) ◽  
pp. 213-228 ◽  
Author(s):  
Victoria DeCocq ◽  
Gautam Bhattacharyya
Keyword(s):  
Organic Chemistry ◽  
Three Dimensional ◽  
Instructional Materials ◽  
External Representation ◽  
Reaction Products ◽  
Representational System ◽  
Chemistry Students ◽  
Research Participants ◽  
Line Angle ◽  
Problem Solving Strategy

We report our qualitative study of twenty-four students enrolled in the second-semester of a second-year undergraduate (sophomore-level) organic chemistry course, Organic Two. We asked the research participants to propose the product and electron-pushing mechanism of elementary mechanistic steps in the absence and presence of the corresponding overall transformation. We also asked the students about their preferences of representational systems when working on tasks common to Organic Two to ascertain the extent to which an external representation, rather than a task, might evoke a problem-solving strategy. In addition to familiarity to instructional materials, the main reason for which the students preferred line-angle formulas for nearly all of the task types is that the representational system allowed them most readily extract relevant, or otherwise useful, information without distracting them. However, line-angle formulas did not seem to cue students to the three-dimensional attributes of molecules; only dash-and-wedge structures and Newman and chair conformers did so. For the electron-pushing tasks, the research participants’ reasoning processes included at least some chemical characteristics of the species involved in the transformation when they were not given the product of reaction. When provided with the overall transformation, however, the students changed their focus to getting to the product. Consequently, they replaced correct answers with incorrect ones when given the reaction products. These results raise the possibility that traditional mechanism tasks may mask students’ mechanistic reasoning ability.

Development of three-dimensional hot pool model in a system analysis code for pool-type FBR

2013 ◽  
Vol 256 ◽  
pp. 264-273 ◽  
Author(s):  
Danting Sui ◽  
Daogang Lu ◽  
Lixia Ren ◽  
Yizhe Liu
Keyword(s):  
System Analysis ◽  
Three Dimensional ◽  
Pool Model ◽  
Pool Type

Distribution of reaction products (theory). VII. D+ + H2 → DH + H+ using an ab initio potential-energy surface

1969 ◽  
Vol 47 (21) ◽  
pp. 4097-4099 ◽  
Author(s):  
I. G. Csizmadia ◽  
J. C. Polanyi ◽  
A. C. Roach ◽  
W. H. Wong
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Energy Surface ◽  
Three Dimensional ◽  
Classical Trajectory ◽  
Reaction Products ◽  
Trajectory Calculation

A three-dimensional classical trajectory calculation has been made of the dynamics of the reaction D+ + H2 → DH + H+. In contrast to earlier trajectory studies the potential-energy surface was obtained ab initio, consequently the results have predictive interest.

Potassium in soils under different cropping systems:1. Behaviour of K remaining in soils from classical and rotation experiments at Rothamsted and Woburn and evaluation of methods of measuring soil potassium

1971 ◽  
Vol 76 (3) ◽  
pp. 539-552 ◽  
Author(s):  
A. E. Johnston ◽  
T. M. Addiscott
Keyword(s):  
Buffer Capacity ◽  
Activity Ratio ◽  
Cropping Systems ◽  
Crop Rotations ◽  
Exchangeable K ◽  
Soil Potassium ◽  
Ratio Equilibrium ◽  
Equilibrium Activity ◽  
Exchange Behaviour ◽  
Classical Experiment

SUMMARYMeasurements made on soils from the Ley–Arable rotation experiments and some of the Classical experiments at Rothamsted and Woburn are described. Values of exchangeable K, equilibrium activity ratio, equilibrium K potential, and buffer capacity are given for each plot. Potassium quantity/intensity relationships measured for each plot showed that no differences in K exchange behaviour have arisen as a result of manuring or of ley or arable treatments. The only fundamental variation was in the quantity of K in the soils. Continuous ley plots, whether given N fertilizer or containing clover, contained much more K than plots carrying crop rotations. In the Classical experiment soils, quantity of K depended largely on manuring.Potassium uptakes by ryegrass grown on the soils from the various plots are discussed. Potassium uptake was well-related to quantity of K, better so than to the other K parameters. The release of non-exchangeable K to the crop was non-linearly related to the fall in exchangeable K in the soils from the Rothamsted Ley-Arable experiments.Drying and re-wetting the cropped soils released K in amounts inversely proportional to the amount of K in the moist cropped soil. This release of K was unrelated to the original exchangeable K contents of the soils.

scholarly journals Dynamics of Different Fractions of soil Potassium in an Inceptisol under Subtropical Rice-Rice System

2020 ◽  
pp. 17-30
Author(s):  
Raghabananda Nayak ◽  
Kumbhakarna Rout
Keyword(s):  
Soil Depth ◽  
Block Design ◽  
Field Studies ◽  
Water Soluble ◽  
Potassium Content ◽  
Rabi Season ◽  
Exchangeable K ◽  
Kharif Season ◽  
Soil Potassium ◽  
Randomized Block Design

Field studies were carried out in 2014-15 rabi season and 2015 kharif season at central farm of OUAT, Odisha, India to evaluate different fractions of potassium at different soil depth at different stages of rice crop. The experiment was laid out in randomized block design with 12 treatments and 4 replications. The study revealed that water soluble K, exchangeable K and non exchangeable K content was highest in 100%NPK+FYM+Lime.Watersoluble K decreased from tillering to harvesting for all the treatments in both the seasons. Exchangeable K decreased in rabi season but increased in kharif season through the stages of growth. Non exchangeable K increased from tillering to harvesting in both seasons. Lime application has increased three forms of potassium over 100%NPK treatment. There was decrease in potassium content with depth. Potassium content in kharif season is less than rabi. The correlation between grain yield is highest with non exchangeable K in rabi and exchangeable K in kharif. The K uptake is best correlated with non exchangeable K in rabi and water soluble K in kharif season.

scholarly journals Study on the earth pressure of a foundation pit adjacent to a composite foundation with rigid-flexible and long-short piles

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0251985
Author(s):  
Yuancheng Guo ◽  
Shaochuang Gu ◽  
Junwei Jin ◽  
Mingyu Li
Keyword(s):  
Three Dimensional ◽  
Earth Pressure ◽  
Friction Angle ◽  
Element Model ◽  
Composite Foundation ◽  
Deep Soil ◽  
Foundation Pit ◽  
Testing Procedures ◽  
Retaining Structure ◽  
Lateral Earth Pressure

Model tests were performed to investigate the lateral earth pressure acting on the retaining structure adjacent to both natural ground (NG) and composite foundation (CFRLP), which were supported with rigid-flexible and long-short piles. Two testing procedures, namely, applying a load to the foundation and rotating the retaining structure along its toe, were considered. The results indicate that the additional lateral earth pressure acting on the retaining structure adjacent to the CFRLP is less than that of the NG in the depth of the reinforcement area strengthened by flexible piles. Compared with NG, the CFRLP yielded a smaller normalized height of application of the lateral earth pressure, suggesting that the CFRLP blocked the horizontal diffusion of the load and had a strong ability to transfer the surcharge load to the deep soil. When rotating the retaining structure, the lateral earth pressure acting on the upper part of the retaining structure experienced limited reduction once the displacement at the top of the retaining structure was greater than 8 mm, whereas the pressure acting on the lower part of the retaining structure continued to decrease with increasing displacement. In addition, a three-dimensional finite element model (FEM) was used to investigate the influence of the pile parameter and the wall-soil friction angle on the additional lateral earth pressure.

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