Questions related to Soil Physics
It is known that soil texture does not change easily, but the effect of soil tillage, soil fragmentation and the passage of agricultural machinery over it, will it affect the soil texture over hundreds of years?
I have estimated some parameters of soil (physical and chemical both). I have also used three different depth of soil. Now I am looking to interpret those data and analysis them. What are the ways to analyze the significance and combine those data?
Do you consider that the availability of soil moisture to crops is solely a function of soil physical properties?
Lee's disc apparatus is designed to finsd thermal conductivity of bad conductors. But I am having a doubt that, since soil having the following properties:
1. consists of irregular shaped aggregates
2. Non uniform distribution of particles
3. Presence of voids
Can we use Lee's disc method find thermal conductivity of soil???
I am interested about how quickly SOM can deplete over time, and would like to start a discussion on the topic. Please pardon me if my question is broad.
In temperate systems, it is common to find annual decomposition coefficients around 1-3% (i.e., 1-3% of the SOM stock is lost after a year). However, I wonder how quickly can SOM mineralization occur.
While reading the literature on SOM changes after deforestation in the tropics, I found values suggesting that SOM stocks can decline by 10-50% in a few years (5-10 years) after a forest is cleared for cultivation.
Also, while looking at the AMG soil organic matter model, I noticed that the potential (maximum) SOM mineralization rate (k0) was set to 29%!
Have you ever asked yourself this question?
Related to this topic, I was thinking of a simple experiment that could shed some light on this question. Let's imagine pots with freshly collected soil or a plot of land, which is outside, and for which any plant development is precluded (removing seed, young seedlings manually). I would be curious to see how quickly SOM changes over time (considering that we would regularly monitor it or regularly SOM contents), given that no plant can inject organic matter. Of course, this soil would be exposed to environmental changes (such as regular water inputs from rain or manual watering, not to let it dry).
Any thoughts about this?
A lysimeter decreased in weight by 120 kg over a period when irrigation and rain was 30 mm. What was the evapotranspiration (in mm) if the area of the lysimeter was 1 m2 an the height 0.8 m ?
It is exciting to see that this year’s Nobel Prize for physics goes to complex system studies. Fingering flow (wetting front instability) in unsaturated soils is a typical complex-system problem. The complex system is partially characterized by emergence and adaptation. For highly non-linear unsaturated flow, the emergent pattern is the fingering, and the corresponding adaptation principle is the optimality, such as the minimization of global flow resistance. Based on these ideas, I have mathematically demonstrated that the relatively permeability is a function of both saturation and water flux, while the traditional theory considers the relative permeability as a function of saturation only. The work was supported by experimental results and documented in a recent book
One key issue in applying the complex-system framework to unsaturated flow is to find a physical principle to describe the adaptation. To do that, does anyone have a more general principle than the minimization of the global flow resistance?
Two major flow mechanisms for preferential flow in unsaturated zone are the existence of macro pores or structures and wetting front stability (fingering flow). Do you have any field evidence or theoretical arguments to tell which of the two mechanisms is more important?
Can total porosity be deduced from the water holding at saturation? That is when soil is at saturation does that mean all pore spaces are filled with water? If this is true can one assume that the total water at saturation is equal to total porosity?
Many literatures pointed out that soil sand content has a greater contribution to soil thermal conductivity. However, I couldn't find any models that can quantify soil thermal conductivity using the results of soil particle size distribution. In frozen soils, things seems more complicated considering the phase change of soil water. I want to find a model to express the soil thermal conductivity. I just want to find a soil thermal conductivity model that takes into account both the soil phase change process and the soil mechanical composition
In my research on soil algae I found that over a period of 3 months the soil pH dropped by 0.6-0.8 units and the algae grew very well. However I did a correlation between the abundance of algae and the respective soil pH and found a positive correlation between, i.e. the more algae there were, the higher the soil pH. I just don't understand why the overall soil pH is dropped from start of the test?
I have found controversy:
Soil water salinity can affect soil physical properties by causing fine particles to bind together into aggregates. This process is beneficial in terms of soil aeration, root penetration, and root growth. Increasing soil solution salinity has a positive effect on soil aggregation and stabilization.
Sodium has the opposite effect of salinity on soils. The primary physical processes associated with high sodium concentrations are soil dispersion and clay platelet and aggregate swelling. The forces that bind clay particles together are disrupted when too many large sodium ions come between them. When this separation occurs, the clay particles expand, causing swelling and soil dispersion. Soil dispersion causes clay particles to plug soil pores, resulting in reduced soil permeability.
So, could you please anyone clarify about this issue with mechanism.
I have known some physical-based models and emperical models, i.e., the original Stefan model (mainly used in permafrost regions) and its modified modes. However, I consider there would be some better methods to quantify the dynamics of frost depth in seasonal frozen soil region.
Due to the characteristics of two-way melting of the soil during the thawing period in seasonal frozen soil regions, the prediction of the frost depth during the thawing period becomes more complicated and difficult. Are there any good methods to quantify the dynamics of frost depth during thawing period?
Do you know the methods to estimate soil evaporation reliably in cold and arid region (especially with shallow groundwater level) other than in-situ experiments during freezing-thawing period? Some researchers used the Penman-Monteith equation to estimate the evapotranspiration during freezing-thawing period. Since there were not any crops in the freezing-thawing period in farmland, things were then concentrated on figuring out how much soil evaporation released. Things would be more complex if there were some land covers (straw, snow, or residues et al) on the farmland. I don't know whether the ET0 calculated by Penman-Monteith equation can represent the soil evaporation scientificly. If not, are there any other recommanded methods ?
Do any temperature changes that occur on upper soil layers affect the rise of groundwater or sub-surface water through temperature gradient?
pH is the negative logarithm of hydrogen ion concentration which describes about concentration of hydrogen and hydroxyl ion present in the system..pH is an important chemical parameters which can directly or indirectly influence soil physical, chemical and biological properties resulting in interfering crop yield and productivity in question...
I am looking for studies that compared soil texture results obtained from field tests (ribbon test, jar test, throw-the-ball test, sausage test, etc.) with results obtained from laboratory.
Have you heard of such studies and, more generally, which field method would you recommend as the most accurate?
Thank you immensely,
I am in need of knowing the general threshold values (optimal ranges) for mangrove growth and rehabilitation, for the following water/sediment parameters?
- Bio-chemical Oxygen Demand (BOD)
- Chemical Oxygen Demand (COB)
- Total Suspended Solids (TSS)
- Organic Matter Content (OM)
- Electric Conductivity (EC)
- Cation Exchange Capacity
- Sediment Texture (Particle Size)
Also interested in what people use the data for and what software they use for fitting data.
In this case, I have a study where soil properties were characterized for 100+ pastures and we are trying to link diverse pasture management activities to changes in soil characteristics. During a recent review we were asked to use a multivariate approach (PCA or regression trees). As a plant ecologist I am very familiar with multivariate analyses for plant communities, where all values in a matrix (e.g. diversity or cover) are of similar units/scale. However, a multivariate approach for soil was never explored previously due to differences in the scale of soil characteristics (e.g. pH, electrical conductivity, to percent C, N, OM, texture, etc.). Could someone offer some advice on how the matrix of soil variables would be prepared for a multivariate test like PCA? Do you adjust the scale of variables with a transformation or run the test with original values?
Particle size distribution (PSD) aka soil texture is a major feature to understand soils.
Sand, silt and clay classes of mineral particles are so commonly used that they become part of the everyday landscape of agronomists, farmers and others.
Why such size limits have been placed between these categories?
Is there a reason?
In addition, different countries may have different PSD classes (eg., 50 µm or 63 µm between silts and sands).
On which scientific basis has this been made?
To follow up on that,
Don't you think that a more modern approach to soil texture characterisation would be more helpful by measuring soil PSd on a continuous scale? rather than splitting between sand, silt and clays.
Indeed, two soil with the same PSD (lets say 30% sand, 30% silt and 40% clay) could be very different.
Within sands, particles could all be towards th coarse side, or conversely towards the fine side.
Same reasoning for the other classes.
Without solid reasons (physical perhaps?) to set the boundaries between sands, silts and clays, that system seems a bit arbitrary and old-fashioned, isn't it?
Shouldn't it be more useful to represent the frequency distribution of particles on a continuous scale to give a more precise picture of the actual texture of a soil.
New techniques such as laser diffraction seem to be useful to this end, and could give a more representative image of the distribution of the size of soil's mineral particles.
Futhermore, current method to determine soil PSD using sieving and sedimentation is extremely long and prone to errors in measurements.
Any thoughts on this?
I am looking for large datasets including information on soils (texture, depths, carbon , etc.) and their location (GPS coordinates or climates data).
Any large studies which would have left their data available for free in repositories?
My objective is to help people find time series on soil carbon on this thread (easily find this discussion with a google search). Thus it could a great reference and link list.
I am performing some tests with pressure plate apparatus on clayey to loamy soils. I need to compare results. However not able to find a reference paper with reported values of moisture content at 0.33 bar and 15 bar pressure.
Kindly help with some studies in which pressure plate apparatus is used and values are reported.
Thanking you in anticipation
My current job is to study soil aggregates and soil microorganisms. I want to extract DNA from individual aggregates and measure some soil physical and chemical properties, such as soil carbon and nitrogen. Our aggregates range in mass from 100 to 300 mg, but DNA extraction takes up a large part of its quality. I want to know what methods can be used to measure soil carbon and nitrogen with small-mass soil samples in individual aggregates.
Thank you in advance.
I have studied an area of rain forest which presents a strong gradient of variation in soil moisture and nutrient. The florestal inventory was conducted in 42 plots of 5-25 meters, distributed in seven lines going through three compartments, in order: 1) A floodable plain forest in a organic soil; 2) Intermediary assembly located in a soil with a steep slope; and 3) a dry forest located in the highest place, with poor white sand soil.
For now, i intend to evaluate the water table variation, but i´m not sure how deep and how many piezometers should be needed to perform multivariate analyses involving plant community and soil water content. Initially, would be interesting install 42 piezometers, 1 per plot, but this would be very difficult to perform. Besides, i am not sure if piezometers of 1,5 meters would be deep the enough to access predictive informations about the influence of soil water content in plant community composition.
Microalgae are a group of lower plants with the capacity of photosynthesis, widely distributed in marine, freshwater, soil and other environments. As we known, Microalgae are grazed by the other soil organisms which can affect nutrient cycling in terrestrial ecosystems significantly through modifying soil physical, chemical and biological properties, especially the soil macrofauna. But the knowledge of the influence of nitrogen deposition on the diversity of forest soil microalgae and Seasonal succession in a soil algal community associated with biogeochemical cycles is not well known.so how to measure the diversity of forest soil microalgae is important. Who can tell me? or who did it ever? Please send me a message, thank you!
The quantification of water-dispersible clay in soils is known to be method-dependent. In this sense, I would like to know the specific steps used by you or your laboratory.
The steps commonly used by me are detailed below:
Laboratory: Lab. of soils. Londrina, Brazil.
1) Mechanical dispersion? Yes.
1.1) Shaking intensity: 200 RPM for 1 to 16 hours.
1.2) Shaking direction: orbital horizontal
1.3) Soil:water ratio during shaking: 20 g to 100 ml.
2) Sedimentation performed in the shaking container? No.
2.1) Sieving before sedimentation? No
2.2) Soil:water ratio during sedimentation: 20 g to 1000 ml.
I conducted CBR tests on unbounded aggregates. As you can see the CBR test results in the attachment, the curves concave up and there is a relatively enormous shift between two test results. Considering that two curves are parallel, it, somehow, can be concluded that two samples has comparable properties, but the presence of the shift make the interpretation of the results difficult.
Based on New Zealand and British standard these curves should not be corrected, however some references in the literature recommended correction of these type of curves (I attached the PDF file).
Question A- If I correct the curves (as explained in the PDF file) or shift the sample-2 the results for two replicated samples are comparable. Under this conditions, do I need to correct the CBR test results?
Question B- If I correct the curve and the resultant curve does not meet 2.5 mm penetration how can I interpret the CBR test results?
Question C- If I should not correct the curves what would be the CBR test results in my case?
I lecture in Soil Physics, one of the issues I face is that we teach a very knowledge based curriculum, in which critical thinking and applied thinking and knowledge to problem solving is rare and difficult to assess. I have been trying to emphasis critical thinking skills by having student review journal papers with poor or misleading science. The difficulty i face is finding these papers in the field of soil physics. please if you know of any papers which present poor soil physics and understanding of scientific concepts could you please let me know.
Good day RG family
I have been using the Keen-Rackzowski method for determining water holding capacity. I have been getting really good results with this method and it's correlating very well with other know soil indicators that improve water holding capacity of soils. The problem is with one set of soils that I am working with. These soils do not absorb water, instead the water stays on top of the soil sample and forms a bubble or runs to the sides instead of infiltrating. What can I do to overcome this problem in the lab? And what causes soil to repel water?
Thank you in advance for your responses.
with or without considering additional means such as irrigation:
could manipulating soil texture (addition/exchange of soil particles) improve physical soil conditions towards higher yields?
It's a basic question, but of applied interest, still not that straightforward to answer as it involves many disciplines and an integrative problem solving approach
lucky to hear your opinion and suggestions
The basic assumption of the function is that the soil was saturated and it's in drying process. This function should take in consideration texture properties and preferably SOM.
If you know a function like this, please add the relevant paper name.
Thanks a lot!!
Dear RG Members,
I'd to know is inferences about soil physical properties (water +granulometry) using RGB +NIR spectrometry is possible?
Thanks in advanced,
Is there an available protocol to perform physical fractionation of soil organomineral fractions using an ultrasonic cleaner instead of ultrasonic probe? If so, I would be very glad if you could share it with me.
I have latitude and longitude of hundreds of locations and I need to extract soil physical and chemical properties from SSURGO. I know there is manual way to extract those information visiting SSURGO website, but it is very inefficient and trouble some when needs for large site. Thus, it would be great if someone can point me the direction. Thank you.
I'm looking for an existing tool (maybe a matlab code or a spreadsheet) to have as an output theoretical models of P-wave velocity variation vs hydrate saturation, in order to compare these models (pore-filling, load-bearing, cementing, patchy) with some real data...
Thanks in advance :)
i want to assess the hydraulic conductivity ( saturated and unsaturated) in the field through diffrent horizon in the vertical and the horizontal direction. how can i proceed to compute an average mean of the hydraulic conductivity of my field ?.
I am currently working on effect of different tillage methods on soil physical properties, growth and yield of Corn in some selected Provence of China. However, l want integrate modelling or simulation into the work.
basically we intend to correlate lab measurements of soil stability (for details see below) with in situ measurements of soil stability. As in situ measurements we already have:
- soil moisture (FDR probe)
- depth of the skid trail (laser)
- shear strength (shear vane tester)
- penetration resistance (hand penetrometer)
- oxygen diffusion rate (ODR meter)
- saturated hydraulic conductivity, ks (hood-infiltrometer)
These methods are not all really simple and fast. So that's the point where I need your creative ideas.
My question to YOU: What other simple field measurements could possibly be correlated to soil stability and/or function?
It could also be something weird, or crazy, something I would not think of in first instance (e.g. sth related to electricity)
Thanks a lot for your feedback,
Background of the question:
Lab measurements, undertaken with samples from the field: pre-consolidation stress and cyclic compressibility, shear parameters, Atterberg limits, saturated hydraulic conductivity, air permeability, texture, water retention curve.
Explanation of the project:
My collegues an me want to assess the impact of heavy forestry machines (29t forwarder) on the stability and function of a loess soil (stagnosol). The trafficking experiments will be conducted on already existing skid trails in a spruce forrest. Different machine configurations (tyres, different kind of belts) will be compared with each other. For each machine configuration different trafficking frequencies and slope inclinations will be simulated.
Laboratory experiments are, as the name already says, very laborous and expensive. Therefore we want to try to correlate the results from the lab to results from the field measurements. WIth the resulting pedotransfer functions it might be possible to derive the parameters from the lab measurements just from simple field measurements, so that in future the laboratory measurements could be skipped. With these field measurements large areas of forest soils could be covered rather easily and hence could be used to create maps of loess soil stability. These maps could serve the rangers as a decision guidance for a soil conserving wood harvest.
Hi all, I've got 100 realizations for 100 years of a climate model data (daily values) which I intend to use for water risk assessment and want to draw some logical conclusions. Could anyone suggest which statistical tools are the most suited to analyse such huge data set?
I am currently undertaking a laboratory investigation on the relationships between soil physical/geotechnical properties and electrical resistivity as part of my PhD. Equipment that I use operates in the frequency range 10Hz to 1kHz. It provides me with a modulus of resistance readings at certain frequency and real and imaginary part of impedance. I would like to know how to, based on these results, determine whether my measurements have been affected by electrode polarization? The literature that I have come across so far does not provide a clear answer. Some papers suggest that below 3kHz there is no effect of electrode polarization whilst others say that 60-100Hz frequency has been chosen to avoid electrode polarization.
Some authors referenced the articles below to justify their choice:
Mitchell, J. K., and Arulanandan, K. (1968). "Electrical dispersion in relation to soil structure." J. Soil. Mech. and Found. Engrg. Div., ASCE, 94(2), 447-470.
Arulanandan, K., and Smith, S. (1973). "Electrical dispersion in relation to soil structure." J. Soil Mech. and Found. Div., ASCE, 99(12), 1113-1132.
Does anyone have an electronic copy of either or both of them that can be shared?
Would be grateful for a response.
Foliar nutrition is becoming popular in the last decade, various products are available in the market (even customized foliar nutrition products), which have been reported to increase yields as well heled in bio-fortification. If we apply micronutrients in the soil, it is most of the time overdose as well the uptake efficiency is very low, the question comes that can foliar micro-nutrition completely substitute for basal (or soil) application?
My understanding of porosity is that it gives you the percentage amount of pore spaces within a given volume of soil. I have worked with a range of soils that vary in their bulk density ranging from 0.89 g/cm3 to 1.69 g/cm3. Literature tells us that soils with high carbon should have low soil density because of the organic matter impact. Based on this my questions are as follows:
1) What is the ideal soil porosity? ( I have read some publications that say land managers should aim for 50%)
2) Is soil porosity of greater than 60% bad for the soil? (My understanding would be that the soil aggregation would be poor when there is very high porosity in a soil?, I stand corrected though)
3) Is there such a thing as too high organic matter in soil? i.e >15%
I hope that my questions are clear, any advice will be appreciated!
I mean soil aggregates are porous materials per se, thus have some cavities on the surface. Depends on the presence of water they may partly or fully saturate with water. I want to determine the volume of these cavities that are open for water to enter.
Thanks in advance.
I know that under the chemical weathering Ferrous (Fe 2+) solve in the water and the because of Oxygen oxidized to the Ferric (Fe 3+) form.
The formation of the crystalline hematite, or any other consequence of the redox reaction, may affect the permeability of the soil or change the mechanical characteristics of it?
I can find the primary minerals that have Fe2+ on their structure, what secondary mineral may result from the redox reaction?
Thank you for your time.
Ascribing doubting as respects making use of the CY Model in FLAC3D so as to mimic the behavior of clayey soil in the seismic analysis to being utilized the friction hardening in the aforesaid soil constitutive model based on the UBCSAND model subsequent to perusing the paper entitled “NON-ASSOCIATED PLASTICITY FOR SOILS, CONCRETE AND ROCK”. In short, are we allowed to exploit the friction hardening for clay? Additionally, is it rational to have the friction hardening and the cohesion hardening instantaneously?
Dear Sir, I would like to monitor soil moisture dynamic at a watershed scale at long time scales. The depth of soil moisture is five meters. Could you please introduce me which instrument is better? Thanks
Soil as earths living skin provides support to both natural and human systems. In good olden days , we use to define the role of soil in terms of sustaining the crop response over a period of time , without incurring any distinguishable depletion of nutrient stock of the soil , either quantity or intensity factor. Of late , we started looking the role of soil beyond soil fertility and plant nutrition , especially with the realisation of negative consequences of global warming . My present set of questions revolve in and around this central theme. These are as follows:
* Is it not true that increasing menace of land degradation ( Irrespective of causal factors) , has opened another role of soil as ecosystem service provider?
* What are the possible ecosystem service , we expect through soil physical , chemical and biological properties , either in isolation or in combination ?.
* What is the carrying capacity of soil , and how does it relate to ecosystem service ?
* How would you define soil health to differentiate with soil quality in terms of ecosystem service ?
* Do you feel , ecosystem service out of a soil narrates the soil health better than defined set of soil properties or they simply go hand-in-hand?
* Can we define ecosystem service of a given soil in spatial and temporal scales?
Your precious responses are always appreciated . My regards
One of the main factor that contribute to soil aggregation is calcium carbonate. How is that even whith high calcium carbonate in sodic soil, we still have poor physical quality ?
Understanding the long-term implications of decreased soil quality will require new information based on advances and breakthroughs in soil science research. A challenge for soil science is the need for interdisciplinary research involving classical soil science subdisciplines—soil chemistry, soil physics, soil biology, soil mineralogy, and pedology.While basic research provides an understanding of fundamental soil processes, increasing trends in land transformations, environmental challenges, and policy issues require interdisciplinary approaches.
Is there any specific time for saturation of the pressure plate with given pressure (eg: 0.5 bar).
For laterally loaded piled raft, is there any relationship between soil reaction and the magnitude of axial force. Or, does axial force affect soil pressure measured along the pile length?
radiation use efficiency (expressed in terms of solar radiation, intercepted solar radiation, PAR, intercepted PAR) for potentially grown condition, as well under various biotic/abiotic stress is very important, which could be used for growth and yield assessment, inputs management options and climate change studies.
I found this interesting paper that reports the relative water content (RWC) in the leaves of 13 woody species (between 77 and 91% of water).
But what about the rest of the tree. Of course I am not expecting an absolute answer as this would vary with species, age, season, health etc. But is there any study that has measured water content in whole trees?
Dear fellow scientists,
In the field of wave propagation in elastic half-space, I am trying to model a problem in ABAQUS.
The problem details is:
A harmonic load is applied at the axis of symmetry of a 2D elastic half space and the response of surface nodes at different distances (going as far as 12 meters) are needed.
The problem I have encountered is that for frequencies lower than approximately 50 Hz, the response (e.g. particle velocity, or displacements) is also harmonic at different distances. But for frequencies higher than the mentioned value, the response is neither harmonic nor oscillating with the input frequency, and it more seems like an impulse response. The graphs can be seen in Figures 1 through 4. Figure 1 shows vertical velocity at the location of the input force of 20 Hz, and Figure 2 shows vertical velocity of a surface node 10m far from the source.
Figure 3 shows the same output for 160 Hz input force, and Figure 4 shows the problem.
Figure 5 shows the model geometry.
1. Density=18 kN/m3
2. Elastic modulus=180 MPa
3. Poisson’s ratio=0.25
4. Rayleigh damping parameters: alpha=1.7 beta=5.5e-4
Input force properties:
1. Magnitude=267 N
2. Frequency=20 ~ 160 Hz
3. Applied as either a point load on a node, or pressure load on element face, the results are roughly the same
1. Element dimension and time increment are selected according to published literature and ABAQUS manual, since the shear wave velocity for this material is around 200 m/s, and the highest input frequency is 160 Hz, the Rayleigh wavelength is 0.8 m, the maximum element size is chosen 0.25 m and maximum time increment 0.0005 sec.
NOTE: I have tried smaller mesh (e.g. 0.01 m), and smaller time increment (e.g. 1e-6 sec), but the problem still persisted.
2. Analysis type: Dynamic Explicit, linear bulk viscosity parameter: 0.06 (changed it to 0 but the problem persisted) and Quadratic bulk viscosity parameter: 1.2 (changed it to 0 but the problem persisted)
3. The result types are History output request at different nodes and with time increment equal to analysis time increment.
4. The analysis time is 1~2 sec, no different results.
I know that the FEM analysis cannot cover this range of frequency, but what can we do to make it work for high frequencies?
With increasing population in several countries in Asia and Africa,they have to double their crop yields in coming decades.However crop yields have been stagnating in different parts of the world . Several possible reasons could be limiting yield potential crops,in sufficient or imbalanced nutrition,limiting soil physical and biological conditions etc. Then how to improve the crop yield in future and meet the food and nutritional needs of growing population?
Dear Soil physicist and colleagues.
We are planning can use the 3D scanner to evaluate soil bulk density. If you have done this kind of measurements and can recommend or alter us about limitations.
Can recommend or make comments about the feasibility to use this kind of equipment in the field ?
I thanks in advance
The importance of soil testing in fertilizer recommendation is now beyond any doubt, especially with the intervention of geo-spatial tools-aided soil fertility variograms. These developments added another dimension of soil test interpretation.On the other hand, in conventional soil testing research or advisory laboratories, the soil samples are stored for different periods. In this regard, i request our learned colleagues to express their views on the following related issues:
* How long , a soil after sampling , can be stored without experiencing any change in physico-chemical properties?.
* How frequently , different soil properties undergo chnges /.
* Has any study been made to see the changes in soil properties in long term storage ?.