Zone 3 soil

Climatic zone 1 Soil N (range) 1 Total soil N 1 Amino acid N... 

Zone 1 soils consist of more than 85% clay and silt (particles smaller than 0.075 mm) and often have sufficient cohesion and low permeability to allow... 

Zone 2 soils consist of coarse silts and fine sands (dg5 > 0.075 mm and djo < 0.6 mm) and these exhibit an increased tendency for the movement of fine soil particles. They are considered to be problem soils with regard to geotextile filters. Table 8.5 shows that the AOS requirement for retention has a smaller range than for Zone 1 soils. 

Ammonium nitrate fertilizer incorporates nitrogen in both of the forms taken up by crops ammonia and nitrate ion. Fertilizers (qv) containing only ammoniacal nitrogen are often less effective, as many important crops tend to take up nitrogen mainly in the nitrate form and the ammonium ions must be transformed into nitrate by soil organisms before the nitrogen is readily available. This transformation is slow in cool, temperate zone soils. Thus, ammonium nitrate is a preferred source of fertilizer nitrogen in some countries. 

Unsaturated Soil Zone (Soil) Modeling 4.2.1 TDE Modeling... 

The book focuses on the biogeochemistry of trace elements in arid and semiarid zone soils and includes an introductory chapter on the nature and properties of arid zone soils. It presents an updated overview and a comprehensive coverage of the major aspects of trace elements and heavy metals that are of most concern in the world s arid and semi-arid soils. These include the content and distribution of trace elements in arid soils, their solution chemistry, their solid-phase chemistry, selective sequential dissolution techniques for trace elements in arid soils, the bioavailability of trace elements, and the pollution and remediation of contaminated arid soils. A comprehensive and focused case study on transfer fluxes of trace elements in Israeli arid and semi-arid soils is presented. The book concludes with a discussion of a quantitative global perspective on anthropogenic interferences in the natural trace elements distributions. The elements discussed in this book include Cd, Cu, Cr, Ni, Pb, Zn, Hg, As, Se, Co, B, Mo and others. This book is an excellent reference for students and professionals in the environmental, ecological, agricultural and geological sciences. 

Coarse-sized particles dominate the particle size distribution of arid soils. Some soils are also quite gravelly. The subsurface horizons commonly exhibit accumulation zones of carbonates, gypsum and more soluble salts. Many arid zone soils are shallow and gravelly, some are alkaline. Their structure is weak. From most soils, clay accumulation horizons (argillic horizons) are absent, or are only weakly developed, and so are minerals that indicate an advanced degree of weathering. 

It seems that clay translocation (argilluviation) from the upper into lower horizons takes place only to a limited extent in arid zone soils. B] horizons are only rarely identified. That limited argilluviation may indeed have taken place in some profiles is also indicated by the clay coatings (argillans) that were observed in subsurface horizons of some soils. Clay migration might possibly have been facilitated by the strong dispersion... 

TRACE ELEMENT DISTRIBUTION IN ARID ZONE SOILS... 

Dissolution of carbonate by NaOAc-HOAc solutions at varying pHs from arid-zone soils, as indicated by X-ray diffraction, are presented in Fig. 4.1. Arid soils from Israel contained varying contents of CaC03 (from 13.7-68.1%). X-ray diffraction showed that calcareous soils used in this study... 

Figure 4.1. Removal of carbonate from Israeli arid soils as indicated by the X-ray diffractograms after extraction of the carbonate fraction by NaOAc-HOAc solutions at various pHs for 16 hours. C calcite d = 3.04 A, and D dolomite, d = 2.89 A. Number 1, 2, 3, 4, 5, and 6 indicate non-treated soil (No. 1), treatments (No. 2-6) with NaOAc-HOAc solutions at pH 7.0, 6.0, 5.5, 5.0 and 4.0, respectively (after Han and Banin, 1995. Reprinted from Commun Soil Sci Plant Anal, 26, Han and Banin A., Selective sequential dissolution techniques for trace metals in arid-zone soils The carbonate dissolution step, p 563, Copyright (1995), with permission from Taylor Francis US)...

Figure 4.2. Dissolution of Ca from Israeli arid soils by NaOAc-HOAc solutions at various pHs after the extraction of the exchangeable fraction (after Han and Banin, 1995. Reprinted from Commun Soil Sci Plant Anal, 26, Han and Banin A., Selective sequential dissolution techniques for trace metals in arid-zone soils The carbonate dissolution step, p 568, Copyright (1995), with permission from Taylor Francis US)...

Various sequential dissolution protocols have been developed by different research groups in order to accommodate their types of soils, experimental conditions, and objectives. This makes it difficult to compare the results with different procedures. We compared two SSD procedures for humid zone and arid zone soils, developed by German and Israeli soil scientists, respectively, based on aggressiveness of extractants, their specificity and selectivity, completeness of phase-extraction by each extractant from defined phases and their effects on subsequent fractions. We also appraised the applicability as well as the limitations of each procedure under different conditions. 

The cumulative sums of selected major and trace metals extracted by the two SSD procedures from representative arid-zone soils are shown in Fig. 4.6. As can be seen from the figure, the Rehovot procedure is stronger in attacking desired fractions, such as the carbonate bound, Mn oxide bound and organically bound fractions. Extraction of certain major elements, indicating selectivity, specificity and completeness of extraction of given soil components, was found to differ between the two procedures. Calcium and Mg were more completely extracted from the carbonate fraction in arid zone soils by the Rehovot procedure. Calcium and relevant trace elements bound in the carbonate fraction, which were not completely dissolved by the Bonn procedure at this step, were released at the following steps, such as the ERO, OM or RO fractions. 

On the basis of this comparison study, at present, it is still difficult to adopt a universal selective sequential dissolution procedure, which may be used everywhere and be suitable for all soils with diversified physical, chemical and mineralogical properties. The application of the SSD procedure must consider individual soil characteristics, such as soil type and properties. The two typical SSD procedures were developed to address soils formed in two climates. The Rehovot procedure was developed to be suitable for the calcareous soils in arid and semi-arid zone soils, whereas the Bonn procedure was created to primarily handle the acid and neutral soils in humid zones. In general, the Bonn procedure appears to be unsuited for calcareous soils in arid and semi-arid zones. The Rehovot procedure has limitations in handling acid and neutral soils, especially forest soils with higher content of organic matter. 

BINDING AND DISTRIBUTION OF TRACE ELEMENTS AMONG SOLID-PHASE COMPONENTS IN ARID ZONE SOILS... 

In Californian soils amended with sewage sludge for seven years, Ni is mostly present in the residual (64%), the organically bound (12%) and the carbonate fractions (18%) (Chang et al., 1984). Nickel in the carbonate fraction is found to increase with time in arid zone soils amended with sludge (Knudtsen and O Connor, 1987). In the sludge-amended calcareous soils of Southeast Spain, the residual and the carbonate bound Ni fractions are the major solid-phase (Moral et al., 2005). 

Figure 5.6. Relationship between Co and Mn contents extracted from solid-phase of six Israeli arid-zone soils with sequential dissolution procedures (after Han et al., 2002b. Reprinted from J Environ Sci Health, Part A, 137, Han F.X., Banin A., Kingery W.L., Li Z.P., Pathways and kinetics of transformation of cobalt among solid-phase components in arid-zone soils, p 184, Copyright (2002), with permission from Taylor Francis)...

Figure 6.1. The fractional loading isotherms of Cu in a contaminated Israeli loessial soil at an initial (one hour) period and after 48 weeks. The soil was treated with increasing levels of metal nitrates and was incubated under the field capacity regime. Horizonal solid line represents the native content of Cu in the nonamended soil (Figure 6.1 - Figure 6.4, after Han and Banin, 2001. Reprinted from Commun Soil Sci Plant Anal, 32, Han F.X and Banin A.,The fractional loading isotherm of heavy metals in an arid-zone soil, pp 2700-2703, Copyright (2001), with permission from Taylor Francis)...

Table 6.5. Reduced partition index (IR) of trace metals in arid-zone soils incubated under saturated paste regime (after Han and Banin, 1997. Reprinted from Water Air Soil Pollut, 95, Han F.X., Banin A., Long-term transformations and redistribution of potentially toxic heavy metals in arid-zone soils. I Incubation under saturated conditions, p 411, Copyright (1997), with permission from Springer Science and Business Media)...

The reduced partitioning index (mean IR values) of Cd, Cr, Cu, Ni and Zn in 45 Israeli arid-zone soils is presented in Fig. 6.7. The trends for mean IR values for five heavy metals in these soils were as follows Cr > Zn = Cu > Ni > Cd (Fig. 6.7) (IR is calculated from Banin et al., 1997a). This indicates that Cr is strongly bound to solid-phase components, possessing... 

Changes of Manganese Partitioning Among Solid-phase Components in Arid-zone Soils Pathways and Short- and Intermediate-term Kinetics... 

The transformation pathway(s) and kinetics of Mn in the solid-phase of two Israeli arid-zone soils incubated under saturated paste and field capacity conditions for a prolonged period of time is discussed below. 

Figure 6.21. Initial and annual distribution and transformations of Mn in the major solid-phase fractions in two Israeli soils. Soils were incubated at the saturated-paste regime (after Han and Banin, 1996. Reprinted from Soil Sci Soc Am J, 60, Han F.X., Banin A., Solid-phase manganese fractionation changes in saturated arid-zone soils Pathways and kinetics, p 1076, Copyright (1996), with permission from Soil Sci Soc Am)...

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