Soil Processes

It is commonly found that about twice as much P and S is released from the soil than predicted, but that the amount of N agrees well with the prediction. What process could account for this  

What does this tell you about the solubility of these ions Does this agree with their observed behaviour in soil  

In each case, calculate the weight of zinc held by 1 g of soil. Plot the graph of weight of Zn held per gram (j-axis) against the final concentration of Zn. 

Fit the data to the Fangmuir equation and plot the graph. Obtain values for and K. 

Derive the relationship between the concentration of Fe ions in solution and pH. 

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The effects that changes in vegetation have on soil carbon pools and nutrient availability are also difficult to evaluate. However, several models have been successful in predicting vegetation-soil nutrient relationships because they assume that such changes occur as a result of different rates of decomposition and nutrient release from leaf litter of different taxa 50, 60), Such predictions could be tested and the models refined or parameterized for new taxa by measuring soil nutrient availability and respiration in stands of different species on the same soil type. For example, fifty years ago the U.S. Civilian Conservation Corps (CCC) established such stands as species trial plots measurements in some indicate large differences in soil nutrient availability (48), Further measurements in these stands would now occur at the same time-scale at which we expect the feedback between species replacement and soil processes to occur. 

The release of ions through weathering is also considered an input to soils. Elements that were bound in mineral crystals are released into the soil solution. These ions can be involved in soil processes and the formation of new organic or inorganic materials, or leached from the soil into the groundwater. 

Simon, A., Larsen, M. C., and Hupp, C. R. (1990). The role of soil processes in determining mechanisms of slope failure and hillslope development in a humid-tropical forest, eastern Puerto Rico. Geomorphology 3, 263-286. 

When new pesticides are developed, their effects upon soil communities are tested. Typically these tests use functional parameters (e.g., generation of CO2 or nitrification) (Somerville and Greaves 1987). Many effects shown on soil communities are of short duration and are thought to lie within the range of normal fluctuations in soil processes. 

Plant survival and crop productivity are strictly dependent on the capability of plants to adapt to different environments. This adaptation is the result of the interaction among roots and biotic and abiotic components of soil. Processes at the basis of the root-soil interaction concern a very limited area surrounding the root tissue. In this particular environment, exchanges of energy, nutrients, and molecular signals take place, rendering the chemistry, biochemistry, and biology of this environment different from the bulk soil. 

Neutral interactions are found extensively in the rhizosphere of all crop plants. Saprophytic microorganisms are responsible for many vital soil processes, such as decomposition of organic residues in soil and associated soil nutrient mineralization/turnover processes. While these organisms do not appear to benefit or harm the plant directly (hence the tenn neutral), their presence is obviously vital for soil nutrient dynamics and their ab.sence would clearly influence plant health and productivity. 

Electroosmotic soil processing is an in situ separation/removal technique for extracting heavy metals and organic contaminants from soils.17 55 89 The fluid between the soil particles moves because a constant, low DC current is applied through electrodes inserted into the soil mass. The electroosmosis (EO) remedial method provides an advantage over conventional pumping techniques for in situ treatment of contaminated fine-grained soils and is more efficient in saturated conditions. 

Greenland, D.J. and M.H.B. Hayes. "The Chemistry of Soil Processes". John Wiley and Sons, New York (1981). 

We are interested in understanding which soil processes are involved in GHG production, and how they work, in several treatments or fertilizers. The production of CO2, N20, and CH4 when crops were grown under in vitro or greenhouse conditions was studied. These experiments were carried out using different types of soil (nitrogen depleted and/or alkaline-saline) and several crops were studied. 

The ammonium dynamics showed that the initial concentrations of N were reduced after the first 3 days, and after that, a release of the mineral occurred from day 3 up to day 14. Later still, the concentration of ammonium decreased by up to < 14 mg N kg 1 dry soil for all the treatments in both the Otumba and Texcoco soils, and the ammonium concentration decreased by up to < 2 mg N kg 1 dry soil for all treatments, except for the soil treated with sterilized sludge, < 31 mg N kg 1 dry soil. The contour of the ammonium dynamics was similar in both the Otumba and Texcoco soils. Many abiotic and biotic processes might affect the concentration of NH4+ in soil, such as NH4+ fixation in the soil matrix, volatilisation of NH3, and immobilization or oxidation of NH4+. Some soil processes were occurring at too low a level to be detectable, such as NH4+ fixation and the volatilisation of NH3. The nitrate dynamics were similar in both soils. The concentration of N03 was 120 mg N kg 1 dry soil in the control treatment in both soils. The ammonium concentration was similar in both soils, > 200 mg N kg 1 dry soil, treatments with sludge reached > 255 mg N kg 1 dry soil and > 300 mg N kg 1 dry soil in the Texcoco and Otumba soils respectively, and soils treated with sterilized sludge increased the concentration... 

Because of the irregular rainfall distribution, mean precipitation values have little meaning in the (semi)-arid zone, if not also the range of variation is indicated. This variability refers to both temporal and spatial variability. Temporal variability affects not only the onset and duration of the rains in the year, but plays also a role in year-by-year differences. The variability is highest in the hyper-arid zone, where the mean precipitation value is composed of a few intensive rainstorms. When these fall on a heated barren surface - as is often the case in the arid zone - a part of it is immediately evaporated and lost for soil processes. High rainfall intensity results on the other hand in a rapid saturation of the surface layers and creates lateral runoff and erosion, in particular on sloping land. Many arid and semi-arid soils show therefore features of gully and sheet erosion. 

Soil solution is the aqueous phase of soil. It is in the pore space of soils and includes soil water and soluble constituents, such as dissolved inorganic ions and dissolved organic solutes. Soil solution accommodates and nourishes many surface and solution reactions and soil processes, such as soil formation and decomposition of organic matter. Soil solution provides the source and a channel for movement and transport of nutrients and trace elements and regulates their bioavailability in soils to plants. Trace element uptake by organisms and transport in natural systems typically occurs through the solution phase (Traina and Laperche, 1999). 

Follett RF, Stewart BA (eds) Soil processes and the carbon cycle. CRC Press, Boca Raton FL, USA, pp 207-223... 

Yilmaz El, Ensari NY (2005) Cadmium biosorption by Bacillus circulans strain EB1. World J Microbiol Biotechnol 21 777-779 Zouboulis AI, Loukidou MX, Matis KA (2004) Biosorption of toxic metals from aqueous solutions by bacteria strains isolated from metal-polluted soils. Process Biochem 39 909-916... 

Golchin A, Baldock JA, Oades JM (1998) A model linking organic matter decomposition, chemistry, and aggregate dynamics. In Lai R, Kimble JM, Follett RF, Stewart BA (eds). Soil processes and the carbon cycle. CRC Press, Boca Raton, pp 245-266... 

It is probable that capillary flow of water contributes to transport in the soil. For example, a rate of 7 cm/year would yield an equivalent water velocity of 8 x 10-6 m/h, which exceeds the water diffusion rate by a factor of four. For illustrative purposes we thus select a water transport velocity or coefficient U6 in the soil of 10 x 10 6 m/h, recognizing that this will vary with rainfall characteristics and soil type. These soil processes are in parallel with boundary layer diffusion in series, so the final equations are... 

Keywords Comparison Functional diversity Molecular tool Organic farming Soil processes... 

The enzymatic activity in soil is mainly of microbial origin, being derived from intracellular, cell-associated or free enzymes. Only enzymatic activity of ecto-enzymes and free enzymes is used for determination of the diversity of enzyme patterns in soil extracts. Enzymes are the direct mediators for biological catabolism of soil organic and mineral components. Thus, these catalysts provide a meaningful assessment of reaction rates for important soil processes. Enzyme activities can be measured as in situ substrate transformation rates or as potential rates if the focus is more qualitative. Enzyme activities are usually determined by a dye reaction followed by a spectrophotometric measurement. 

Porazinska DL, Bardgett RD, Blaauw MB, Hunt HW, Parson AN, Seastedt TR, Wall DH (2003) Relationships at the aboveground-belowground interface plants, soil biota, and soil processes. Ecol Monogr 73 377-395... 

PROFILE is a biogeochemical model developed specially to calculate the influence of acid depositions on soil as a part of an ecosystem. The sets of chemical and biogeochemical reactions implemented in this model are (1) soil solution equilibrium, (2) mineral weathering, (3) nitrification and (4) nutrient uptake. Other biogeochemical processes affect soil chemistry via boundary conditions. However, there are many important physical soil processes and site conditions such as convective transport of solutes through the soil profile, the almost total absence of radial water flux (down through the soil profile) in mountain soils, the absence of radial runoff from the profile in soils with permafrost, etc., which are not implemented in the model and have to be taken into account in other ways. 

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