Loamy soil

Hassen A., Jedidi N., Cherif M., M Hiri A., Boudabous A., Van Cleemput O. Mineralization of nitrogen in a clayey loamy soil amended with organics wastes enriched with Zn, Cu, and Cd. Bioresour Technol 1998 64 39-45. 

Fig. 9.1. Sorption of selenate (SeO ) to a loamy soil, showing mass sorbed per gram of dry soil, as a function of concentration in solution. Symbols show results of batch experiments by Alemi et al. (1991 their Fig. 1) and lines are fits to the data using the reaction KA, reaction Freundlich, and Langmuir approaches.

We consider as a first example sorption of selenate (SeO ), as predicted by the reaction K(, reaction Freundlich, and Langmuir approaches (Sections 9.1-9.3). Alemi et al (1991) observed the partitioning of selenate in batch experiments between 10 g of a loamy soil and 20 ml of a pH 7.5 solution containing small amounts of Na2Se04 their results are shown in Figure 9.1. 

Lead may leach from loamy soils of clay target shooting sites, where soils contain about 50,000 mg Pb/kg (about 40% Pb as particulate Pb shot in the most contaminated areas) leachates at 100 mm depth contained up to 3.4 mg Pb/L vs. little or no lead in leachates collected from soil containing background concentrations of lead (Rooney and McLaren 1999). 

Sensitive terrestrial plants die when soil zinc levels exceed 100 mg/kg or when plant zinc content exceeds 178 mg/kg DW (Table 9.5). The phytotoxic zinc level for barley (Hordeum vulgare) is not known, but zinc content of barley leaf rarely exceeds 100 mg/kg DW (Chang et al. 1983). Uptake of zinc from soils by plants depends on soil type for example, uptake is lower in coarse loamy soils than in fine loamy soils (Chang et al. 1983). Zinc uptake by barley leaf is greater with increasing rate of sludge application, but the relation is not proportional (Table 9.5). 

Incubations of heptachlor with a mixed culture of soil microorganisms for 12 weeks showed conversion of heptachlor to chlordene, 1-exohydroxychlordene, heptachlor epoxide, and chlordene epoxide. A mixed culture of soil microorganisms, obtained from a sandy loamy soil, degraded heptachlor epoxide to the less toxic 1-exohydroxychlordene. Conversion was about 1% per week during the 12-week test period (Miles et al. 1971). 

Loamy soils treated with heptachlor at 25 pounds per 5-inch acre, over a 5-year period from 1958 through 1962, contained about 5% of the applied dosages in the fall of 1968, primarily in the form of heptachlor epoxide. In addition toy-chlordane and nonachlor, which were present in the original heptachlor formulation, two toxic metabolites (heptachlor epoxide and a-chlordane) and three unidentified compounds were detected, thus indicating the breakdown in soils of heptachlor and related compounds (Lichenstein et al. 1970). 

Good drainage is essential, but otherwise plums and their close relatives are not unduly fussy about soil. Japanese and American cultivars prefer sandy or loamy soil, while European cultivars do well in clay soil. 

Fig. 12.1 Transport of (A) azinphosmethyl, and of (B) tetradifon in the loessial loamy soil upper layer (0-30cm) under two irrigation regimes (dry and wet) and (C) tetradifon to a depth of 110 cm under irrigation and rainfall. (Yaron et al. 1974)...

Boron deficiency is particularly prevalent in light-textured soils in which water-soluble borates are gradually leached down the soil profile and become unavailable to plants. Heavier, more loamy soils tend to retain more boron because they contain an abundance of compounds, such as humic acids, that can complex boron. Certain crop types have higher boron requirements and benefit most from supplementation. These include soybeans, cotton, peanuts, oil palm, apples, and almonds. 

Droogers, P, Fermont, A. and Bouma, J. 1996. Effects of ecological soil management on the workability and trafficability of a loamy soil in the Netherlands. Geoderma 73 131-145. 

Khomutova, T. E., L. T. Shirshova, S. Tinz, W. Rolland, and J. Richter. 2000. Mobilization of DOC from sandy loamy soils under different land use (Lower Saxony, Germany). Plant and Soil 219 13-19. 

Rhizodeposits from loamy soil diluted by addition ... 

Figure 14.9. Principal component analysis of Py-FI mass spectra of rhizodeposits from a loamy soil and the same loamy soil diluted with 50% of quartz. The soils were grown with maize for 20 days and leached with distilled water. Py-FIMS was done with a 5-pi liquid rhizodeposit that was evaporated in the quartz sample tube (Leinweber et al., 2008a).

As an example of differences in soil residue persistence between the organophosphates and chlorinated hydrocarbon pesticides, parathion and malathion residues were present at the 0.1 p.p.m. level within 8 days of application whereas aldrin [according to Lichtenstein (23)] when applied at the same concentration, persisted 5 months longer as did aldrin and dieldrin at 40% of the applied dosage. Decker et al. (12) report that aldrin and dieldrin residues in soils never exceeded 13.2% of the total applied when tested one year after the last application. Other workers (24) have reported that on a loamy soil, under existing weather conditions, aldrin and dieldrin residues were present at a level of approximately 20% of the total applied insecticidal dosage over a 5-year period. 

Meanwhile, based on another study reported by A. B. Moustafa et al [2], sandy, silty, loamy, clayey, and sandy-loamy soils were impregnated with three types of binding materials, namely, urea formaldehyde, phenol formaldehyde, and sodium silicate. Ammonium chloride, hexamethylene tetramine, and sodium fluorosilicate were used as catalysts for the previously mentioned substances, respectively. Some physico-mechanical tests were carried out with the stabilized soils and different parameters affecting the strength, absorption and durability of stabilized soils were studied [3]. 

Figure 9-11. Valve-like properties of the upper layer of a loamy soil under dry versus wet conditions (a) a dry crust and (b) wh ile being wet by rain. Water is lost gradually across the dry crust but readily enters the wet soil. Water movement is also influenced by gravity, the x elevant component of the water potential (pwgh) decreasing by 0.01 MPa per meter depth in the soil. For a depth of 5 mm, the gravitational contribution decreases 4 by 0.00005 MPa compared to thesoil surface, which increases the influx rate by 25% for the wet condition compared to considering only AP, as is done here (the influence of the 0.00005 MPa gravitational component is negligible for the diy condition).

---