Alkali soil

Generally, the most common cations in the soil solution are potassium, sodium, magnesium and calcium. Alkali soils are high in sodium and potassium, while calcareous soils contain predominantly magnesium and calcium. Salts of all four of these elements tend to accelerate metallic corrosion by the mechanisms mentioned. The alkaline earth elements, calcium and magnesium, however, tend to form insoluble oxides and carbonates in nonacid conditions. These insoluble precipitates may result in a protective layer on the metal surface and reduced corrosive activity. 

Zinc is the 24th most abundant element in the earth s crust. The Zn concentration in the lithosphere is 50-70 mg/kg (Vinogradoc, 1959 Adriano, 2001). Basic igneous rocks contain higher Zn (70-130 mg/kg) than metamorphic and sedimentary rocks (80 mg/kg). Carbonate and limestones contain low Zn (16-20 mg/kg) (Aubert and Pinta, 1977). The total Zn concentration in the soils of the world ranges from 10 to 300 mg/kg (Swaine, 1955), with average concentrations from 50 to 100 mg/kg (Aubert and Pinta, 1977). Arid and semi-arid soils vary from trace levels (subdesert soils) to 900 mg/kg (saline alkali soils) (Aubert and Pinta, 1977). The average Zn concentration in the arid and semi-arid soils of the U.S. (62.9 mg/kg) is... 

Vertisols formed from amphibolite in the Central African Republic contain 300-1000 mg/kg Cr, 11-200 mg/kg Cu, trace amounts to 6 mg/kg Mo and 60-300 mg/kg Ni (Aubert and Pinta, 1977). In chernozem soils of the flood plains of the Amur region, the average Cr is 400 mg/kg. High Co concentrations (100-300 mg/kg) have been found in soils. Manganese concentrations in lithomorphic vertisols are in the range of 3000-5000 mg/kg. Soils on clayey sediments, solonetses and saline alkali soils contain 50-75, 40-100 and 10-50 mg/kg Ni, respectively. 

In chernozems formed on serpentinite diluvium, Co content is in the range of 10-30 mg/kg, while in chestnut and chestnut vertic soils, Co concentrations vary from 3-15 and 15-45 mg/kg, respectively. Soils on basalt, andesite and gabbro contain 15-68 mg/kg total Cu. Total Mn in chernozems is in the range of 520-850 mg/kg. Chestnut soils have 42-106 mg/kg Zn content. Total Zn in saline alkali soils is in the range of 40-60 mg/kg Zn. Bioavailable Zn (ammonium acetate-extractable Zn) in chernozems, chestnut soils and saline alkali soils of the steppe zones varies from trace amounts to 3.8 mg/kg (1-8.3% of total Zn). In chernozems of Northern Bulgaria, total B is in the range of 25-53 mg/kg. Boron increases in saline soils and saline alkali soils. 

Soils in Uzbekistan have an average Co of 17 mg/kg. Total Cu in humic soils is in the range of 18-22 mg/kg, and total Zn is 83 mg/kg. In subdesert soils formed on loessial clayey loams and saline alkali soils, total Mo is 2.6-4.5 mg/kg, and Mo in some soils is as high as 8 mg/kg. Total Zn in subdesert soils varies from 60-112 mg/kg. Sodium acetate-extractable Zn in these subdesert soils is 2.1-3.2 mg/kg, accounting for 2.3-5.1% of total Zn. In saline alkali soils formed on loess and marine clays, total B content is 160 mg/kg. The exchangeable Mn in arid and semi-arid soils is 7-50 mg/kg, accounting for 0.7-7.8% of total Mn. Saline soils in the Ustyurt region contain 42-80 mg/kg of Pb. 

Total Mo in soils of Russia varies from 1-20 mg/kg. In the Stavropol region, total Zn is in the range of 14.4-71 mg/kg. In the Rostov regions, total Zn is 680 mg/kg. Manganese content varies from 600-1000 mg/kg. Saline soils have low concentrations of total Co. In saline soils, total Cu varies from 60-64 mg/kg and in the very saline alkali soils, Cu is 164 mg/kg. 

In cherozems of Serbia, soil boron is in the range of 25-40 mg/kg. The average B content is 30 mg/kg. Boron content increases with salts in arid soils. Saline salts and saline alkali soils contain 40-65 mg/kg total B. 

The total Zn concentration in 45 Israeli soils varies from 7.94-144.2 mg/kg with an average of 56.1 28.7 mg/kg. Terra-Rossa soils contain higher Zn than rendzina soils. Total Zn concentrations in Mediterranean red soils vary from 200-215 mg/kg, while brown isohumic soils on calcareous sandstone contain 48 mg/kg total Zn. However, soils on alluvians from aeolian deposits have 82-90 mg/kg, and saline alkali soils contain 100-200 mg/kg of total Zn. EDTA-extractable Zn varies from 1.9-13 mg/kg, representing 1.7-9.6% of the total Zn in Mediterranean red soils, reddish-brown isohumic soils and rendinas soils (Aubert and Pinta, 1977). 

Moreover, salts in arid soils increase concentrations of boron. In Israeli soils, total B content in saline alluvial soil is in the range of 150-170 mg/kg, four to six times higher than that in alluvial soils (25-40 mg/kg) (Aubert and Pinta, 1977). The soluble boron contents tend to increase with decreases in rainfall. Bioavailable Mo represents an average 2-20% of total Mo. The percentages of bioavailable Mo are higher in arid and semi-arid zones than in humid zones. Bioavailable Mo is 35.8% of the total Mo in soils of Israel and increases to 50-60% in saline alkali soils in India (Aubert and Pinta, 1977). Total Se concentrations in the western United States are higher... 

Kanwar J.S., Singh S,S. Boron in normal and saline-alkali soils of the irrigated areas of the Punjab. Soil Sci 1961 92 207-211. 

Singh, M.V., Abrol, I.P., Transformation and movement of zinc in an alkali soil and their influence on the yield and uptake of zinc by rice and wheat crops. Plant Soil. 1986 94 445 149. 

Richards, L.A. (ed.) Diagnosis and Improvement of Saline and Alkali Soils. United States Department of Agriculture, Washington, D.C. (1954)... 

Typically when a soil is submerged the concentrations of water- and acid-soluble P increase, reach a peak or plateau, and then decrease (Figures 4.11c and 4.13). For the soils shown in the figures, the peak P concentrations in solution were smallest for acid soils high in active Fe and greatest for a sandy soil low in Fe. The increases in acid-soluble P were greatest in an alkali soil low in active... 

Pasricha NS, Ponnamperuma FN. 1976. Ionic equilibria in flooded saline, alkali soils the K+ — (Ca + - -Mg +) exchange equilibria. Soil Science 122 315-320. 

Boron is the 38th most abundant element on Earth. It makes up about 0.001% of the Earths crust, or 10 parts per mdhon, which is about the same abundance as lead. It is not found as a free element in nature but rather in the mineral borax, which is a compound of hydrated sodium, hydrogen, and water. Borax is found in salty lakes, dry lake-beds, or alkali soils. Other naturally occurring compounds are either red crystalline or less dense, dark-brown or black powder. 

United States Salinity Laboratory (1954) Diagnosis and improvement of saline and alkali soils. 

In kaolin (clay) processing, sulfur dioxide reduces colored impurities, eg, iron compounds. In the bromine industry, sulfur dioxide is used as an antioxidant in spent brine to be reinjected underground. In agriculture, especially in California, sulfur dioxide is used to increase water penetration and the availability of soil nutrients by virtue of its ability to acidulate saline—alkali soils (327). It is also useful for cleaning ferric and manganese oxide deposits from tile drains (328). 

Bremner, J. M. (1950). Some observations on the oxidation of soil organic matter in the presence of alkali. /. Soil Sci. 1,198-204. 

Transfer of solute with and relative to the moving water and competitive adsorption of solutes are central to amelioration of saline and alkali soils, agricultural chemical location in soils and management of wastes in soils. This paper illustrates how space-like coordinates based on the distribution of the solid and the water help analyse these problems. We focus on the macroscopic or Darcy scale of discourse [6], which permits unambiguous measurement of the key elements of the flow equations, and we restrict ourselves to 1-dimensional flow, because that seems to limit analysable experiments. 

Bower, C. A., F. F. Reihmeier, and M. Fireman. 1952. Exchangeable cation analysis of saline and alkali soils. Soil Sci. 73 251-261. 

U.S. Salinity Laboratory Staff. 1954. Diagnosis and improvement of saline and alkali soils. USDA-Agricultural Handbook No. 60. U. S. Government Printing Office, Washington, DC. 

Gupta, R.K., Chhabra, R., and Arbol, I.P., Fluorine adsorption behavior in alkali soils Relative roles of pH and sodicity, Soil Sci., 133, 364, 1982. 

Sulfur has been recognized since the mid-1800 s as an essential element in plant nutrition, crop requirements being similar to P needs. Sulfur is also used as a soil amendment in the reclamation of saline and alkali soils. 

Organics in water have been investigated and provided some interesting data [63]. Except for nitrites [64], chemically unstable substances have not been studied. Wells associated with the disease are situated on alkali soil [65], but the finding was restricted to a single endemic area and has not been reproduced. 

Soluble salts—halite (NaCl) and gypsum (CaSC>4 2H2O), as well as sulfides (pyrite, FeS2) in soils reclaimed from seas or swamps. These minerals readily dissolve in percolating water or, in the case of the sulfides, are readily attacked by oxygen. Saline and sodic ( alkali ) soils are examples of this category. 

The traditional and recently proposed classification categories for salt-affected soils are given in Table 11.1. Saline (white alkali) soils are those in which plant growth is reduced by excess soluble salts. These soils can be converted to normal soils by leaching the excess salts from the plant root zone. The pH of saline soils... 

Sodic (black alkali) soils are a particularly difficult management problem. The water permeability of these soils to water is very slow. The pH of sodic soils is commonly greater than 9 or 9,5, and the clay and organic fractions are dispersed. Dispersed organic matter accumulates at the surface of poorly drained areas as water evaporates and imparts a black color to the surface, hence the name black alkali. Sodic soils are found in many parts of the western United States. In some locations they occur in small patches, slick spots, less than 0.5 ha in extent. Such patches occupy slight depressions, which become accentuated as surface soil particles disperse and are blown away by wind erosion. The percolation of insufficient water to satisfy plants and to control salinity is the main problem associated with sodic soils. In addition, their relatively low soluble-salt concentrations and high pH values can result in direct Na toxicities to the most sensitive plants. 

Tolgyesi GY (1976) Relationships between localization of alkali soils and the sodium excretion of cattle. Magy Alltatarv Lapja 6 297 - 299. 

Molybdenum is adsorbed as an anion in the clay fraction, and that reduces its availability in fine-textured soils. Singh and Singh (1966) observed a significant negative correlation between available Mo and the silt or clay content in alkali soils. Prasad and Pagel (1976) also found a... 

Agarwal, R. R., Yadav, J. S. P., and Gupta, R. N. (1982). Saline and Alkali Soils of India. New Delhi Indian Council of Agricultural Research. 

Little information is available on the distribution of Mo in the soil profile. In alkaline soils. Mo is more mobile, and if it is not leached from the profile it can accumulate in plants. Pasricha and Randhawa (1971) reported that the available Mo in the surface horizons of recently reclaimed sodic soils in Punjab varied from 0.012 to 0.449 pggr with an average value of 0.112 pgg as compared with subsurface samples in which the values of available Mo ranged from 0.065 to 0.720 pgg with a mean of 0.207 pgg Ahmad, Khathak, and Perveen (1991) reported that the available Mo in the Dir district of Pakistan varied from 0.10 to 1.39 pgg in the topsoil and from 0.12 to 1.31pgg in the subsoil. Misra and Misra (1972) observed high amounts of available Mo in surface soils and a tendency for it to decrease with depth in an alkali soil profile, but not so in the black and red soils, in Uttar Pradesh. The available Mo content decreased with depth in salt-affected soils in Haryana and... 

Other inhibitory substances may also gain entrance to the soil and affect the decay process. These include the accumulation of end products of biological action, excess salt concentration from fertilizers or from alkali soils, and pesticides or herbicides. None of these, except excess alkali in dry regions, are likely to be important in the decomposition process, since many species are involved with widely different tolerances for harmful substances. 

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