Soil Chemistry - Science topic

Tween 80 is an ester formed from the reaction of polyethoxylated sorbitan and oleic acid. Though the reaction product is neutral, a small amount of sulfuric acid is sometimes used to catalyze esterification reactions such as the one that forms Tween 80. Is it possible that Tween 80 contains a small amount of residual sulfuric acid from the reaction that produces it? This would account for the decreasing pH as you increase the concentration of Tween 80.

A number of variables can affect how polycoated urea reacts in soils with differing textural properties under various agroclimatic conditions. Here are some broad ideas to keep in mind:

1. Agro-climatic Conditions: Agro-climatic conditions encompass factors like temperature, rainfall, humidity, and seasonal variations. These conditions can affect the rate of urea release from polycoated coatings and subsequent availability to plants. Higher temperatures can accelerate the release of urea, while excessive rainfall or humidity can increase the chances of urea leaching or denitrification.

2. Soil Texture: Texturally divergent soils, such as sandy, loamy, or clayey soils, have different physical and chemical properties that can influence the behavior of polycoated urea. For instance, sandy soils have low water and nutrient retention capacity, which may affect the release and availability of urea to plants. Clayey soils, on the other hand, have higher water and nutrient holding capacity, which can affect urea release differently.

3. Soil pH and Microbial Activity: Soil pH affects the conversion of urea to ammonium and subsequently to nitrate through microbial processes. Different soil pH levels can impact the efficiency of the polycoated urea and its response in terms of nutrient availability. Microbial activity in the soil also plays a role in urea hydrolysis and nutrient release.

4. Coating Properties: The specific characteristics of the polycoated urea, such as coating thickness, solubility, and release pattern, will influence its response in different soils. Coatings with thicker layers or slower-release patterns might provide a more controlled release of urea, reducing nutrient losses and optimizing plant uptake.

5. Crop Type and Nutrient Demand: The type of crop being cultivated and its nutrient requirements can influence the response of polycoated urea. Some crops may have higher nitrogen demands during specific growth stages, and the controlled release provided by polycoated urea can align better with their nutrient requirements.

It is significant to note that depending on the particular soil and climate circumstances, polycoated urea performance can change. To establish the best use and performance of polycoated urea in various locations, specialized research, field tests, and professional guidance taking into account the unique agro-climatic and soil features of the region are required.

Dear Sudip Ghimire

Soil structure can be influenced by several factors, including:

Soil is not a group of mineral elements accumulated on top of each other, but rather it is a vital medium that contains in addition to the mineral elements a variety of plant and animal organisms that play a major role in soil formation and development. They play an important role in the biochemical reactions that take place in the soil and that result in the transformation of Organic matter into humus and the preparation of nitrogenous materials necessary to feed plants. These reactions are activated when the natural conditions (heat, ventilation, humidity) are suitable for the activity of these organisms.

Dear Layth Saleem Salman Al-Shihmani ,

You asked an interesting question on the relationship between soil physical appearance and soil fertility. Allow me to proceed as follows:

For a soil to be said to be fertile, it must have a sustainable supply of the right quality and quantities of soil ameliorates which translate to nutrients. There are a number of physical parameters that might indicate fertility status of a soil cohort. However, these factors are not a guarantee that the soil is fertile.

Generally, black -dark colored soils are a positive indicator of the soil fertility status of the soil. They are good absorbers of heat which activates microbial activity hence soil biomass recirculation. This is a common case in 2:1 and 2:2 clay minerals which are generally good nutrient suppliers.

On the other hand,light-bright colored soils such as 1:1 Montmorillonites are generally poor nutrient holders due to poor heat absorption capacity, greater reflection thus poor nutrient churning capacity.

We shall all agree that this can be established by the naked eye.That,large grained soils are generally considered as poor nutrient suppliers as compared to middle grained soil such as Ferrasols,assuming all other factors remain constant. Average soil is directly proportional to water holding capacity, soil Rhizosphere aeration which in turn affects Biota Respiration.

Large grained soils such as sandy soils are loosely attached, prone to erosion. They are also poor water reservoirs due to increased percolation.

Related to point number 1 is vegetative cover. Material cover is directly proportional to soil nutrient fertility status. Such soils might have deeper top layer, zone A and B.A good covered soil shall harbor more soil microbes which accelerates decomposition.Humus,a product of decompostion,makes such soils appear much darker.

Whereas soil physical factors might an indicator of soil fertility status, farmers and researchers should be encouraged to do a completed soil laboratory tests. Some of the physical factors mentioned above could be as a results of other underlying causes such as parent material, soil pollution, environmental degradation etc. Instead of dealing with symptoms which might result to wrong diagnosis/prescription, I recommend soil laboratory analysis.

I think bray-II preferable for acidic soil to test p from acidic soil.

Such a material can be used for the treatment of Acid Rock/Mine Drainage in mine site remediation. See https://www.imwa.info/piramid/files/PIRAMIDGuidelinesv10.pdf for instance.

Hi Tamjid, according to my understading, these limits of detection and quantification should be determined for every method, as every method will have different conditions (the column, the analytes to analyze, flow, mobile phase, injection volume, etc). These limits are determined through the validation of the analytical method. After method validation. you can continue and quantify your samples in a reliable way. As an example of method development and validation, you can see this publication. I hope this helps

Oxidation and microbial proliferation leads to SOM loss. So as long as it is safe from oxidation and microbes there will be no loss of SOM. But still if tillage is done in soil and exposure of surface soil to sunlight is happen then it will take very less time for SOM to loss.

Both are negative logarithm of hydrogen ion. Apparently soil pH is measured with 1:2 ratio soil : distilled water. And soil water pH is directly measured by pocket pH meter in wetted soils. So both are more or less same.

Thomas Fungenzi Tough question but i dont think that the carbonates can be found in the acidic soils as it is found or in fact present in the alkaline soils

Extraction of trace elements soluble in aqua regia was used as a decomposition method in accordance with ISO 11466: 1995 E.

1 g sample was weighted accurately in a reaction vessel; 0.5 ml of tri-distilled water was added to obtain a slurry, followed by 9 ml of HCl (12 mol l-1) and 3 ml nitric acid (15.8 mol l-1) .Then 10 ml of 0.5 mol l-1 was added to the absorption vessel which was connected to the reflux condensor. Both apparatus were placed on the top of the reaction vessel. The samples were allowed to stand for 16 h at room temperature in order to reduce the produced during the subsequent heating cycle. They were heated under reflux until boiling for 2 h and allowed to cool slowly at room temperature. The contents and the following rinses of the absorption vessel were passed through the condenser into the reaction vessel. The content of the reaction vessel was transferred quantitatively to a 50 ml graduated flask and filled up to the mark with nitric acid (0.5 mol l-1). After the undissolved material has settled, the supernatant solution was subjected to analysis by ICP-AES.

A blank sample containing the acids used for digestion was prepared in the same way.

In general wet digestions excluding hydrofluoric acid do not attack the silicate matrix. Hence, the separation of the silicate matrix as an insoluble residue from the soluble elements lead to both lowering the dissolved solid concentration in solution and the detection limits for analytes, respectively.In addition, the procedure is carried out in closed system and losses of volatile elements can be eliminated.

With kind regards, N Daskalova

Calcium oxalate

Please find the attachments.

Regards.

This is a good question.

R studio!

Of course, the EPA website (U.S. Environmental Protection Agency

) will help you find what you are looking for.

https://www.epa.gov/

I think phosphatic fertilizers are very slow in nature and hardly achieve 20% PUE in Indian condition. Facts, under acidic soil availability may be higher. Their losses or adsorb on soil particles are very common. This may be applicable for highly water soluble fertilizer using in drip or sprinkler irrigation. Do work and Good Luck for this.

I'd recommend the answer of Sal Mangiafico

@ Gautam, as your soil pH value is low, at that pH soil bacteria may change the sulphur to sulphuric acid, resulted further lowering of soil pH.

Excellent, do you find any distinct variation in soil test values as per stand of different forest species , let us look at the root density vis-a- vis root education dictating such variation in soil test values , including K...

Video link for determination of Point of zero charge (PZC)

Dear Nguyen,

Among the variables analyzed, the compatibility with normal distribution of all variables analyzed can be evaluated using the Kolmogorov–Smirnov test.

Differences between groups can be established by Student’s t -test for normally distributed values and by Mann-Whitney U-test for nonparametric values.

Pearson's correlation coefficient can be searched to examine the relation between normally distributed variables.

Spearman’s correlation coefficient can be used for nonnormally distributed values. Statistical significance was defined as P <0.05 or <0.01 etc...

Best regards...

Dear Gautam,

In the case of this discussion, I am totally in agreement with the statements and thoughts of Shubham. He explained the issue as well. I am specifically a soil ecologist and zoologist and I am also concerned about issues related to physical and chemical properties of soil. Thank you for your precision. Good luck.

Best, Elaheh

yes its do it

Bulk density (BD) measurement needs to be done by core method for any comparison to other soils' BD. If the SOC is very high in soils under forest for a long time, BD may be really low.

The scenario of C:N in WB forest soils is difficult to explain as C always shows higher values than N. If this is a truly real situation, it is intriguing in Soil Science and needs to be probed with great care.

@Dipankar Bera

Yes, you are right. Only solution is to plot such q-q plot, residual vs best fitted and etc. Regression fit line for multiple variables is not possible but #Goutam Kumar Das sir you can use MLR model using R-Stat software to show plot in a single frame that helps to fit the regression line for each (One X as dependent variable and one Y as independent variable).

Convey my thanks for such a relevant article that nicely elaborated of the carbon draining from the terrestrial forest floors arrested in the mangroves ecosystems and that is seen at a glance, I will go through the paper later on and use as citation in my work

I totally agree with Fazel Mohammadi-Moghadam that we need more studies to be done around the world to repeat the idea and evidence. It is a very interesting discussion we are countering here. During my PhD study, I have done a long-term research investigating the effects of 20 years climate influence on soil fauna and vegetation. I think 12 years can also be considered as a long-term research and these discussed obtained results maybe show the effect of higher temperatures on increasing the decomposition rates. Although this is a perception and it really needs to be studied in detail.

Dilip Kumar Pal

Zahid Fazal

First thing, I would present this to the external lab. Perhaps they can look back at notes, strip charts or other outputs to check for mistake. Then if that fails, present the truth with the possible erroneous value and cross checked with other methods, and discuss briefly in findings. Like suggested, if the whole journal paper has no value with this issue included, then you will probably get some bad marks from editor or reviewers, possible suggestions to recover. When you say the value from lab is extremely unlikely or unnatural, it is likely the lab just made a mistake, it happens. It would be better for them to review the circumstance and your cross checking, and agree there was a mistake and then use your value based on their agreement, with a footnote perhaps briefly mentioning this attached to the value. Other issues can develop such as if your cross checking followed much later in time and samples were not preserved and/or stored properly. You may have to justify your work too.

That might be anomalous, I will repeat the analysis for the particular Sample.

Dear Šoster,

If the limestone is not hard and compacted (later case need thin sectioning), you can try to use boiling water and adding hydrogen pyroxide with a continuous stirrer for at least 72 hours (best for chalky and marly limestone). This method leads to getting better and clean tests usually. If they still coagulate, you can add, but be careful, very very little amount (one drop or two) of diluted sodium hydroxide (the later dissolved calcareous tests and etching siliceous tests).

Dear Toyin, use boiling water and hydrogen pyroxide for at least 72 hours with stirring give much better, clean residue chalky limestone, marly limestone, and shale.

Good Luck

Thank you Hermes Pérez-Hernández

I think the suggested paper is interesting but it focuses on hydrology.

biochar

How does biochar transform acidic soil into acidic

→What does alkaline or acidic really mean? Free hydrogen ions H+, more acidic means more H+. Hydrogen ions are positively charged and biochar pores are negatively charged. So the H+ ions will be bound by the biochar which decreases the free H+ ions in the soil. Less H+ means more alkaline.

The ash in biochar makes the soil even more alkaline (be carful when using ash in soils that are already alkaline). Ash has potassium carbonate,I am not sure how much you like the chemical side of things... but it is the same idea, potassium carbonate ans silicate ions can react with H+ and form bonds with it.

The K/Mg ratio can be indicative of how available the potassium and magnesium are in the soil. If for example your ratio is less than 0.25, it typically indicates that the magnesium in the soil is over powering the potassium in the soil making it harder for the plants root system to uptake potassium. If the ratio is >0.35 it can indicate that the plant may have trouble accessing magnesium.

High potassium demand crops also require attention to K:Mg balance and as we increase potassium application we must pay attention to Mg balance. The ideal K:Mg ratio in meq is 0.2 to 0.35 for most crops and crops such as potato 0.3 to 0.4. Often times in trying to satisfy a crops K requirements yield loss is experienced with over application of K by inducing Mg deficiency. Percent saturation levels of K and Mg in the soil are key to understanding when Mg needs to be applied with K to avoid this K:Mg imbalance in a fertility program.

Hanuman Singh Jatav

Dear Jatav,

In the last decade or so, there have been remarkable advances in our knowledge of various topics in soil science. It is not possible to list all of them, so I will try to recall some based on what has been discussed in conferences, and what has been published in soil science journals. These include the fate and effects of antibiotics in soils, 4 per mile initiative, clay-organic matter interactions, soil change due to anthropogenic impact, biological soil health indicators, biochar effects on soil properties, soil variability at the aggregate and soil profile scales, use of non-invasive techniques for soil research, nano-fertilizers, temporal and spatial variability of soil properties, factors controlling nutrient availability in soils, the role of dust deposition on soil development, silicon dynamics in soils and ecosystems, pedometrics, pesticide transport in soil, indicators of soil development, the genesis of technosols, fate of heavy metals in soils, new methods of soil analysis, and many others.

Keep safe,

Victor Asio

1. Take 10 g of soil sample in 50 ml or 100 mL beaker (1:2.5 Soil water suspension ratio)

2. Add 20 or 25 mL of distilled water, stir well for about 5 minutes and keep for half an hour.

3. Again stir just before immersing the electrodes and take the pH reading by using pH meter.

NOTE: Prepare standard buffer solutions of 4.0, 7.0 and 9.2 in distilled water.

Clay particles tend to retain or fix phosphorus in soils. Consequently, fine-textured soils such as clay loam soils have a greater phosphorus-fixing capacity than sandy, coarse-textured soils. Clays of the 1:1-type (kaolinite) have a greater phosphorus-fixing capacity than the 2:1-type clays (montmorillonite, illite, vermiculite). Soils formed under high rainfall and high temperatures contain large amounts of kaolinitic clays, and therefore have a much greater fixing capacity for phosphorus than soils containing the 2:1-type clay. High temperatures and high rainfall also increase the amount of iron and aluminum oxides in the soil, which contributes greatly to the fixation of phosphorus added to these soils.

1) Take 0.5 or 1.0 g 0.2 mm sieved soil sample into a 500 ml capacity conical flak.2) Add 10 ml of 1 N potassium dichromate solution and 20 ml of concentrated sulphuric acid, gently mixed and keep the contents for 1/2 hour.3) After 30 min, add 200 ml distilled water, 10 ml phosphoric acid, about 0.2 g NaF and 8 to 10 drops of diphenylamine indicator.4) Titrate the contents against the standard ferrous sulfate or ferrous ammonium sulfate till it becomes bright green in colour.5) Run a blank titration by following all the above steps without soil.6) After noting down the burette readings of both blank and sample titrations, calculate the organic carbon present in the soil using the following formula

How Can I neonicotinoids usage Statistical data?

Walkley-Black chromic acid wet oxidation method (1934) is best method.

Hi Paul, he want to make colloidal silica, the main method is using cation exchange resin to remove sodium or potassium from sodium and potassium silicate.

Excellent answer given by Paul Reed Hepperly.

1) By adding organic matter humus can form phosphohumic complexes which is easily assimilated by plants, humate ion can replace phosphate ions and humus can form coating around the Fe and Al ions so that coating prevent P from fixation....

2) There are P - solubilizing organisms a) Bacteria - Pseudomonas and Bacillus

b) Fungi - Aspergillus and Pencillium

3) VAM Fungi can increase the absorption of P from soil by extension of root system

4) Placement (Band placement) of fertilizers (Placing the fertilizer below the seed can reduce the fixation of P by reducing the contact between the soil and fertilizer)

5) Liming of acid soils also release fixed P from Fe and Al compounds

@ Kamyar, many minerals in soils are negatively charged and, as a consequence, can attract and retain cations such as calcium , magnesium, sodium, potassium and ammonium etc. Cation exchange is a reversible process, in which elements or nutrients that can held in the soil and lost through leaching can subsequently be released for crop uptake. Certain organic compounds also contribute to cation exchange capacity. Additionally CEC is influenced by soil pH. A certain portion of the total negative charge is permanent, while a variable portion is pH dependent. Values of cation exchange capacity are in the range of 1.0 to 100 cmol (+)/kg, least for sandy soil and high for clay soil. Similarly, higher CEC value reflects the dominance of 2:1 clay minerals, and lower value reflect the presence of 1:1 clay minerals.

I have also observed this. At elevated temperatures, some elements will dissolve into the solid solution of the crucible. Look into the ceramics literature on vitrification. I would not worry about the color change, nor would I be concerned about contamination unless you are ashing a sample for subsequent digestion and quantification of elements in the ash. If you're simply looking at soil carbon, the altered crucibles will continue to be fine. Disregard the etching and color change. Keep in mind though that some elements like potassium volatilize at high temperatures (> 500 C).

Ashok - H2O2 is used to remove organic matter from sediments - not carbonates. If you are trying to remove carbonates, but wish to leave any clay minerals unaffected, you should use a buffered sodium acetate/acetic acid solution (pH 5.3). If you aren't concerned about the clay minerals, dilute HCl would be fine. E-mail me if you would like the method.

Here is an article on the subject, unfortunately from pot experiments.

All your main focus crops are legumes: it means that they will not react to N fertilizers doses (except if soils are deprived in organic matter and by the way in symbiosis bacterias). Then the difficulty in testing low doses o P and K (and have significant effects) is due to the interference of P and K soil reserves and exchange capacities! Soil nature and soil analytical chemical status will indicate if there is any interest in testing low doses of P or K fertilizers for a "short" term response i.e. their effects could be "medium" or "long" term !

Organic matter of the soil is associated with the climatic factor and the microbiological sphere of the soil. And also contacted with chemical absorption of the soil.

Brassica juncea is the most suitable plant for phytoremediation of heavy metals.

First of all, It depends on the type of adsorbent material that you used.

In heavy metal removal processes, desorption/regeneration of adsorbents is one of the essential aspects as it controls the economy of water treatment technology.

For effective regeneration of adsorbents and metal recovery, acids (such as HCl, H₂SO₄, HNO₃, HCOOH and CH₃COOH), alkalis (such as NaOH, NaHCO₃, Na₂

CO₃, KOH and K₂CO₃), salts (such as NaCl, KCl, (NH₄)₂SO₄, CaCl₂2H₂O, NH₄NO₃, KNO₃ and C₆H₅Na₃O₇2H₂O), deionized water, chelating agents and buffer solutions (such as bicarbonate, phosphate and tris) were used in various studies.

I think phytoremediation is the most feasible method for removal of heavy metals from contaminated soil.

Make sure swat is accessing the correct SWAT2012.mdb database. This file should be in your ArcSWAT project folder. When you create an ArcSWAT project, before doing anything, go to "Edit SWAT Input" ---> "Database" and make sure your soil and landuse and other databases are all there and are correct.

Chemical Speciation and Potential Mobility of Heavy Metals ...

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3330713/

Excellent question and answers, according to our team study in Iran: lead in water pipes , traffic intensity , residential wastes , vehicles and urban industries !

Please kindly see the attached article!

Dear A. Mannan Rouhani

A mere 11 elements constitute 99.9% of the atoms in the human body. These are typically divided into major and minor elements. The four major elements, H, O, C, and N, make up approximately 99% of the human body, and seven minor elements, Na, K, Ca, Mg, P, S, and Cl, make up another 0.9% of the body (Combs 2005). Approximately 18 additional elements — called trace elements — are considered essential in small amounts to maintain human life. However, human health experts do not universally agree on the exact number and identity of these trace elements. Out of the approximately 29 elements considered essential for human life, 18 are either essential or beneficial to plants and are obtained from soil, and most of the other elements can be taken up from the soil by plants (Brevik 2013a).

Negative Health Effects

Heavy Metals

Exposure to heavy metals through soil contact is a major human health concern. Arsenic is a metalloid, but it is commonly grouped with the heavy metals. The heavy metals of greatest concern for human health include: As, Pb, Cd, Cr, Cu, Hg, Ni, and Zn (Fergusson 1990). Heavy metals enter soils naturally through the weathering of rocks, but they have also been introduced into soils through human activity. Heavy metals are the by-products of mining ores, and they are present in mine spoils and in the immediate surroundings of metal processing plants. Heavy metals are released into soils from landfills that contain industrial and household wastes and from sewage sludge that comes from wastewater treatment plants. E-wastes, or wastes associated with electronic appliances, are an increasing source of Pb, Sb, Hg, Cd, and Ni in the soil (Robinson 2009). Urban soils are particularly susceptible to significant accumulations of heavy metals from automobile exhaust, coal burning, erosion of metal structures, and refuse incineration. In agricultural settings, the use of fertilizers, manures, and pesticides has also contributed to the accumulation of heavy metals in soils (Senesi et al. 1999). Arsenic has been used in pesticides, and the build-up of arsenic in orchard soils is problematic since it may persist for decades (Walsh et al. 1977). The heavy metals with the most toxicity in humans, including Cd, Pb, Hg, and As, are those with no biological function that disrupt enzymatic activities commonly affecting the brain and kidneys (Hu 2002).

Organic Chemicals

Organic chemicals have been deposited into the soil both naturally and anthropogenically, and many of the organic chemicals deposited into the air and water eventually end up in the soil. Soil contamination with organic chemicals is a serious problem in all nations (Aelion 2009). A large amount of these organic chemicals come from the agricultural application of herbicides, insecticides, and nematicides (Figure 2). Soil pollution with organic chemicals is not limited to farming areas. Soils in urban areas are also polluted with organic chemicals as a result of industrial activities, coal burning, motor vehicle emissions, waste incineration, and sewage and solid waste dumping (Leake et al. 2009). Both farming and urban areas have soil contamination that includes a complex mixture of organic chemicals, metals, and microorganisms caused by municipal and domestic septic system waste, farm animal waste, and other biowastes (Pettry et al. 1973). A more recent health concern includes pharmaceutical waste derived from antibiotics, hormones, and antiparasitic drugs used to treat humans and domestic animals (Albihn 2001).

The most common types of organic chemicals found in soil include polyhalogenated biphenyls, aromatic hydrocarbons, insecticides, herbicides, fossil fuels, and the by-products of fossil fuel combustion (Burgess 2013). These organic chemicals are highly diluted in the upper layers of the soil, and they form chemical mixtures used in reactions involving microorganisms. We have very little toxicological information about the health effects of these chemical mixtures (Carpenter et al. 2002). Studies of the health effects of low concentrations and mixtures of these chemicals in soil have been very limited (Feron et al. 2002). Due to the very long half-lives of many organic chemicals, they are referred to as "persistent organic pollutants." These persistent organic pollutants are organic chemicals that resist decomposition in the environment and bioaccumulate as they move up the food chain. An example of this is 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), which was shown to disrupt the hormonal systems of raptors (Vega et al. 2007).

Airborne dust can impact human health, especially when the particles are less than 10 microns in size (Monteil 2008). The main direct health effect of inhaled dust is irritation of the respiratory passages and diseases, such as lung cancer. However, airborne dust can carry additional materials, such as pathogens, harmful gases, organic chemicals, heavy metals, insects, pollen, and radioactive materials, that can cause other health problems (Bartos et al. 2009). Humans can breathe airborne dust containing toxicants into the lungs, where the toxicants may enter the bloodstream. Cultivation for agricultural production and deflation (wind erosion) from unpaved road and work sites and denuded fields can introduce dusts into the atmosphere. Airborne dust from Africa is a significant health concern for North American soils. Clouds of dust from the Sahara and Sahel deserts follow the trade winds across the Atlantic Ocean, and African dust has been linked to elevated levels of Hg, Se, and Pb in North American soils (Garrison et al. 2003). The number of asthma cases in the United States more than doubled between 1980 and 2000, and asthma rates have also increased in the Caribbean (Brevik 2013a). Airborne dust from Africa has been tentatively linked to increased asthma in North America (Monteil 2008).

Soil Pathogens Although most organisms found in soil are not harmful to humans, soil does serve as a home for many pathogenic organisms. Bacteria are the most abundant type of organism in soil, and they are found in every soil on Earth. Most fungi are saprophytes that absorb nutrients by aiding in the decomposition of dead organisms, but approximately 300 soil fungi species out of the more than 100,000 total fungi species are known to cause disease in humans (Bultman et al. 2005) (Figure 3). For example, the soil fungus Exserohilium rostratum was responsible for the 2012 fungal meningitis outbreak in the United States (Brevik & Burgess 2013a). Protozoa are single-celled eukaryotic organisms. Most protozoa found in soil feed on bacteria and algae, but some cause human parasitic diseases such as diarrhea and amoebic dysentery (Brevik 2013a). Helminths are parasites that may inhabit the human intestines, lymph system, or other tissues. Diseases caused by helminths require a non-animal development site or reservoir for transmission, and the soil is a common development site. Billions of people are infected by helminths worldwide each year, with an estimated 130,000 deaths annually. Helminth infections generally occur through ingestion or skin penetration, and in most cases involve infection of the intestines (Bultman et al. 2005). The soil is not a natural reservoir for viruses, but viruses are known to survive in soil. Pathogenic viruses are usually introduced into soil through human septic or sewage waste. Viruses that cause conjunctivitis, gastroenteritis, hepatitis, polio, aseptic meningitis, or smallpox have all been found in soil (Hamilton et al. 2007; Bultman et al. 2005).

Temperature, rainfall got definite relationship with vegetation and soil organic matter and soil organic carbon. These are long established phenomenon.

Dear Dr Fungenzi

You may have seen my response to your first question. One of the attached papers (the first one) was based on a publicly available time series of samplings. We used 41 years and by now there should be data for another 10 years available. The samplings and storage of data takes place at the Swedish University of Agricultural Sciences, Uppsala, Sweden. In case you want a contact I will be happy to support you.

Best regards

Björn Berg

Dear Marlon

Andisol with a high content of humic compounds, the majority of the proportion of Al-amorphous will be complexed to Al-humic, so it makes sense that in Andisol with high organic content, Al-humic> Al-amorphous. Conversely, at andisol with low OM content, only a small portion of Al-amorphous complexed to Al-humic so that Alo> Alp content

Veli Uygur Yes Sir, I prepared ferrihydrite with different concentrations of P, and confirmed. but I didn't find a suitable reference for my work i.e. the digestion of P sorbed iron colloids, the way I did.

Mohammed JARULLAH Farhan

Hi Nitish,

A soil sample is extracted with an excess of 1 M ammonium acetate solution. The amounts of exchangeable sodium, potassium, calcium and magnesium in the extract are determined by flame photometry (Na and k) and by atomic absorption spectrophometry (ca and Mg). lanthanum or strotium is added as a releasing agent to prevent formation of refractory compounds which may interfere with determinations (e.g. phosphate),

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Recommend Manohar Sehgal answer

Never, never and never try to create an artificial salinity in a normal soil as it does not represent a typical salt affected soil. It is a wastage of time, energy and resources. Instead, you collect soil which is naturally saline or sodic or saline-sodic. You can get the information from soil test laboratories there about the locations in Bangladesh where such problem soils exist naturally. Good Luck.

Following

Mohammed JARULLAH Farhan .

Dear Xavier Dupla

Have a look at this published paper. hope be useful.

It depends on the toxic metal concentration of the soil and plant type, if the toxic metal content was below than tolerable level of certain plant, no need to control the availability of toxic metals.But, In the case of toxic metal surpassed tolerable level, you need to control the mobility in order to let the accumulation plants live in the substrata. no need to much worry about metal availability after the treatment, only the accumulation plant grow relatively well, plant rhizosphere will mobilize the metal

Currently, only 1.2% of the world agricultural land is under organic farming. However, because of increasing consumer preference for organic products, organic farming has been increasing steadily. India has 9th largest agricultural land area (1.5 M ha) used for organic farming by in excess of 800,000 producers. The largest land mass used for organic farming is in Australia (27 M ha), much of which is under extensive grassland.

There is plenty of literature available on organic farming soil quality, mostly comparison between soils from conventional farming versus organic farming. One example is Y. Ikemura and Manoj K. Shukla, Journal of Organic Systems – Vol.4 No.1, 2009.

Many studies have also shown, nitrate leaching losses have been lower from organic farming compared to conventional systems. Studies have also found, generally while crop/animal product yields have been lower in the organic systems, it has been offset by the higher product price fetched by the organic systems. Interestingly, it has been found organic systems also emit lower greenhouse gases (GHGs).

To date, organic farming studies have shown, highly improved physical, chemical and biological properties of soils which have resulted in better water holding capacity, soil fertility and lower environmental impacts.

A review on organic farming could help to highlight the above findings (K.S. Lee et al. / Journal of Environmental Management 162 (2015). I suggest you search for more open access papers.

Mr. Phogat,

Via MS.

I have had a significant amount of experience with prairie soils in the north central US (mostly mollisols). In my evaluation of cropland soils, grassland soils, and wetland soils, I have found the C:N ratios almost always at about 11:1 +/- 1 which is at the 10:1 value. This is assuming that the soils are in equilibrium with their management and environment. This can vary, usually when additional plant/animal biomass is added but due to the microbial equilibrium reestablishing shortly after the biomass is added, returns to near the equilibrium level.

An interesting sidelight of evaluating soil C:N ratios is their usefulness in evaluating environmental pollution or contamination. Contamination from hydrocarbons will widen the C:N ratio due to the excess C while fertilizer contamination will narrow the C:N ratio due to excess N. the rebound from each of these types of contamination take some time to rebound and evaluating C:N on a periodic basis can be used to evaluate effectiveness of remediation.

*The retention is the presence of ions on the surfaces of ion exchange complexes called the image available.

*The fixation is the capture of ions between the inner layers of clay minerals or other soil particles or enters into the chemical formula of the crystal structure called an image that is not available.

*Adsorption is the retention of ions on the surfaces of the ion exchange complexes in a readily available form.

*Absorption is the process of penetration of ions into the structural structure of clay minerals, especially montmorillonite.

A new soil extractant (H3A) with the ability to extract NH4, NO3, and P from soil developed and tested against 32 soils, which varied greatly in clay content, organic carbon (C), and soil pH. The extractant (H3A) eliminates the need for separate phosphorus (P) extractants for acid and calcareous soils and maintains the extract pH, on average, within one unit of the soil pH. The extractant is composed of organic root exudates, lithium citrate, and two synthetic chelators (DTPA, EDTA). The new soil extractant was tested against Mehlich 3, Olsen, and water for extractable P, and 1 M KCl and water‐extractable NH4 and NO2/NO3. The pH of the extractant after adding soil, shaking, and filtration measures for each soil sample.

1. Morgan Extraction Reagent which was introduced in 1941

2. Mehlich introduced an universal extractant, frequently referred to as the Double Acid extractant, for assaying acid sandy textured soils.

3. The ammonium bicarbonate‐DTPA extraction reagent for use on alkaline soils was introduced.

4. Wolf modified the Morgan extraction reagent by adding DTPA to it. In 1984, Mehlich described his Mehlich No. 3 extraction reagent for use on a wide range of acid soil types.

All above extraction reagents can be assayed using a multielement analyzer such as the inductively coupled plasma emission specterometer for both the major elements and micronutrients in the obtained extractant.

The soil extract can be prepared by mixing 5g of soil in 1L H2O mix well, filter and then