Soils property

Many factors affect the mechanisms and kinetics of sorption and transport processes. For instance, differences in the chemical stmcture and properties, ie, ionizahility, solubiUty in water, vapor pressure, and polarity, between pesticides affect their behavior in the environment through effects on sorption and transport processes. Differences in soil properties, ie, pH and percentage of organic carbon and clay contents, and soil conditions, ie, moisture content and landscape position climatic conditions, ie, temperature, precipitation, and radiation and cultural practices, ie, crop and tillage, can all modify the behavior of the pesticide in soils. Persistence of a pesticide in soil is a consequence of a complex interaction of processes. Because the persistence of a pesticide can govern its availabiUty and efficacy for pest control, as weU as its potential for adverse environmental impacts, knowledge of the basic processes is necessary if the benefits of the pesticide ate to be maximized. 

Migration 244. Accumulation 245. Structural Geology 246. Traps 251. Basic Engineering Rock Properties 254, Basic Etigineering Soil Properties 266. 

Soil is distinguished by the complex nature of its composition and of its interaction with other environmental factors. No two soils are exactly alike, and extremes of structure, composition and corrosive activity are found in different soils. Climatic factors of rainfall, temperature, air movement and sunlight can cause marked alterations in soil properties which relate directly to the rates at which corrosion will take place on metals buried in these soils. 

The modern procedure to minimise corrosion losses on underground structures is to use protective coatings between the metal and soil and to apply cathodic protection to the metal structure (see Chapter 11). In this situation, soils influence the operation in a somewhat different manner than is the case with unprotected bare metal. A soil with moderately high salts content (low resistivity) is desirable for the location of the anodes. If the impressed potential is from a sacrificial metal, the effective potential and current available will depend upon soil properties such as pH, soluble salts and moisture present. When rectifiers are used as the source of the cathodic potential, soils of low electrical resistance are desirable for the location of the anode beds. A protective coating free from holidays and of uniformly high insulation value causes the electrical conducting properties of the soil to become of less significance in relation to corrosion rates (Section 15.8). 

Combination electrical methods Tomashov and Mikhailovsky describe a method developed in the Soviet Union. This test is essentially a combination of resistivity measurement and polarisation rates on iron electrodes in soil in situ. The usefulness and value of this procedure has not as yet been determined by practical application by corrosion engineers. The development of this combination test does, however, represent an attempt to integrate some of the complex factors controlling corrosion rates in soil. Much more research on these factors and methods of measurement should in the future enable the corrosion engineer to evaluate soil properties with respect to application of corrosion-alleviating operations. 

Table 8. Effect of supergd on soil properties and plants growth [10, 131]... 

Plutonium, deposited on soil, moves downwards with a rate which depends on precipitation and soil properties. In dry, sandy areas, the downward rate may be 1 mm/year, while in rainy areas it may be 10 times higher (3). The rate is considerably reduced in clay soil. 

Relaxed foundation requirements may allow for poorer soil properties, hence allowing a broader site selection. 

DeBano, L.F. Rice, R.M. Conrad, C.E. Soil heating in chaparral fires Effects on soil properties, plant nutrients, erosion, and runoff. Berkeley, Calif. Pac. Southwest For. and Range Exp. Stn., Forest Service, USDA 1979, Res. Pap. PSW-145. 21 p. 

Jenny (1941) attempted to quantitatively relate the factors of soil formation to soil properties such as N, C, or clay content, depth of leaching... 

Andisols Andie soil properties (A1 humates, low pH, darkly colored A) Volcanic parent materials... 

The combined influences of runoff generation mechanisms, runoff flowpaths, and soil properties together control runoff chemistry. In spite of the wide range of interactions that characterize terrestrial environments, a few broad generalities can be offered, as the chemical composition of streamflow typically contains... 

Tan, T. K. (1957). Discussion on Soil properties and their measurement. Proc. 4th Int. Soil Mech. and Found. Engng. 3, 87-89. 

In regions where erosion is transport limited, weathering rates are controlled by the supply of reactive fluids to unstable minerals. This is controlled by soil properties, regional base level, and ultimately, sea level. 

Repercussions of Soil Properties and Irrigation Water Quality on Crop Growth Under... 

Soils properties are very sensitive to the type of exchangeable ions. Calcium imparts favorable physical properties to the soil, while adsorbed sodium causes clay dispersion and swelling. It is generally recognized that an exchangeable sodium percentage of 10 is sufficient to cause soil dispersion, reduction of soil permeability and impaired growth of some crop plants. On the other hand, excess salt concentration prevents the dispersive effect of adsorbed sodium. 

To enable comparison to this experimental approach, archaeological human bones of various ages and soil properties (Table 9.1) from the Anthropological Collection in Munich were analyzed. All German skeletal series come from humic soil with, neutral to slightly basic pH. The samples from Tinkey, Syria, coastal Pern and Egypt have been buried in dry, sandy soils. Soil samples from most of the excavation sites were available and bone sample... 

Lambe, T. W. Michaels, A. S. (1954). Altering soil properties with chemicals. Chemical Engineering News, 32, 488-92. 

Number and locations of test sites and required soil properties Cropped vs bare-soil surface Small vs large plot Application type... 

Soil properties A Soil texture (sand, silt, clay), organic matter/carbon content, and pH Stones, roots, and hardpans must be largely absent to allow representative sampling of soil profile Soil properties should appear uniform over test site Soil texture data should be available at time of site selection. Soil properties must match study purpose. This can be realistic use conditions, realistic worst-case or worst-case in terms of agrochemical mobility and persistence Must ensure that the majority of samples can be taken from the deepest sampling horizon. Information about sub-soils can be obtained from soil maps, test coring and on-site interviews... 

---