Soils reducing

Small tire chips have also been utilized as a soil amendment to improve athletic playing fields (see Recreational surfaces). A patented process marketed under the trade name Rebound (fai Tire) combines cmmb mbber from scrap tires with composted organic material to reduce soil compaction, resulting in better athletic playing surfaces (52). Installations have been made in Florida, California, Colorado, Hawaii, Maryland, Michigan, Missouri, Nevada, Virginia, and Wisconsin. 

Colloidal Stabilization. Surfactant adsorption reduces soil—substrate interactions and faciUtates soil removal. For a better understanding of these interactions, a consideration of coUoidal forces is required. 

APPLYING BIOSOLIDS REDUCES SOIL EROSION (Case Study 3)... 

To reduce soil acidity and keep cropland productive, farmers amend the soil by liming, which is the application of limestone. Limestone is calcium carbonate, and the carbonate anion is the conjugate base of hydrogen carbonate. Liming therefore increases the concentration of hydroxide in the soil, thereby increasing the pH C03 ((3 q) + H2 0(/) HC03 (<3 g) + OH (<3 q)... 

Although in many. soils with tow P availability, significant desorption of sparingly soluble Pi forms requires at least millimolar concentration levels of specific carboxylates (e.g., citrate, oxalate) in the soil solution, much lower concentrations (0.1 mM) were necessary to reduce. soil adsorption of Pi, which was applied simultaneously with carboxylates (100). Thus, competition of carboxylates with Pi for P sorption sites in the soil matrix may be a mechanism that can. 

G. J. D. Kirk and M. A. Saleque, Solubilization of phosphate by rice plants growing in reduced. soil—prediction of the amount solubilized and the resultant increase in uptake. E. J. Soil Sci. 46 247 (1995). 

It reduces runoff velocities and do reduces soil erosion... 

The density of soil may control the presence, absence, or density of roots found in a particular soil layer. The density of plant roots in a soil layer determines how much water plants can remove from the layer and its rate of removal. Soil compaction, in addition to inhibiting root growth, reduces soil-water-holding capacity. A model that does not consider the effect of soil density on water balance may produce significant errors in water balance estimates. 

Control pressure relationships to reduce soil gas entry. 

The saturated soils that occur during wetland, or lowland, rice cultivation give rise to a set of physical, chemical, and biological properties that are quite different from upland soils. Rice is the only major row crop produced under flooded-soil conditions and the absence of air-filled pores along with reduced soil-atmosphere interactions result in an almost entirely different set of processes than those occurring in upland cropping systems. 

Indian mustard (Brassica juncea Czern L.), tall fescue (Festuca arundinacae), birds foot trefoil (Lotus corniculatus), and kenaf (Hibiscus cannibinus) have been used to reduce soil Se levels near Los Banos, California. Total Se concentrations in soil depths from 0 to 60 cm were lower in all cropped plots than in the bare plots after four years (Banuelos, 2000). The efficiency of Se lost from the soil after four years for each of the four crop rotations was in the range of 17-60% (Banuelos, 2000). The cropped plots with only tall fescue had 25% lower soil Se concentrations after four... 

Fig. 3. High concentrations of dimethyl sulfide (a) and depleted concentrations of methyl butane (b) correlate with reducing soils over the kimberlite (depicted as the grey zone).

Buffering strips Reduce soil erosion Lacas et al. (2009)... 

Biological exposure pathway of sulfur movement in soils of forest ecosystems is related to microbial transformation of sulfolipids. Back conversion of sulfate-S into organic matter immobilizes the anion and potentially reduces soil cation leaching. Processes of sulfur mineralization and incorporation proceed rapidly in response to several factors, including temperature, moisture, and exogenous sulfate availability in soils and water. 

TandUch, R. Vrana, B. Balaz, S. 2003, Monitoring of Polychlorinated Biphenyls in Slovakian Freshwater Sediments Use of Semipermeable Membrane Devices. In The Utilization of Bioremediation to Reduce Soil Contamination Problems and Solutions Sasek, V., Glaser, J., Baveye, P. Eds. Kluwer Academic Publishers Dordrecht, The Netherlands 221-226. 

When a reduced soil is re-oxidized, Fe " " changes into Fe(OH)3. The original Fe oxides are thus distributed differently, generally with a higher specific surface and activity. In high-activity clay soils, this may increase the stability of the structure established just before flooding. In low-activity clay soils the effects of alternate reduction and oxidation are less clearly beneficial, partly because of leaching of nutrients. 

Table 4.3 Some possible mineral phases in reduced soils and their equilibrium constants...

There is evidence that mixed Fe(II)-Fe(III) hydroxides are formed. These can be produced easily in vitro by partial oxidation of pure Fe(II) hydroxy salts and they have some of the observed properties of the solid phase Fe(II) found in reduced soils, including the grayish-green colours characteristic of reducing conditions in soils. This material is green rust and has the general formula Fe(II)6Fe(III)2(OH)i8 with Al + partly substituted for Fe + and Cl, S04 and C03 substituted for OH . 

Note that although the pe-pH-[Fe ] relationships shown in Figure 4.7 are consistent with control by the Fe(OH)3-Fe3(OH)g system, in fact various other reduced Fe solid phases are possible and as discussed above it is difficult to establish unequivocally which phase controls Fe solubility in reduced soils. 

Figure 4.17 Profiles of (a) Fe(II), (b) Fe(III) and (c) pH in columns of reduced soil exposed to O2 at one end for different times. Points are experimentally measured lines are predicted using the model described in the text with independently estimated parameter values (Kirk and Solivas, 1994). Reproduced by permission of Blackwell Publishing...

Figures 6.15 and 6.16 give the profiles of Fe(II) and Fe(III) concentration and pH measured by Begg et al. (1994) and Kirk and Bajita (1995). Blocks of reduced soils were placed in contact with planar layers of rice roots, with the roots separated from the soil by fine nylon mesh which they could not penetrate.

Figure 6.15 Profiles of ferrous and ferric iron and pH in blocks of two reduced soils in contact with planar layers of rice roots for indicated times in Iloilo soil. Iloilo soil is a highly weathered sandy loam, org C = 1.2%, aerobic pH = 3.4, reducible Fe = 80 mmol kg (Begg et al., 1994). Reproduced by permission of Blackwell Publishing...

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