Representative soil sample

Sampling of the Soil. Representative soil samples were taken from conventional and no-tillage plots before planting and afterward at intervals of 1 month since April, 1985. The soil samples were placed in quart jars, frozen immediately by using dry ice, and stored at -18 °C. 

Table 2 gives the composition of a representative soil sample from each landing site. The composition of the soils from the various locations can also be compared with the results of the chemical analyses of the lunar surface made by the unmanned space probes, Surveyor V, VI, and VII (Table 1), and the data from the x-ray fluorescence experiment (Table 4). The latter experiment made use of the fluorescence x-rays emitted from the lunar surface due to excitation by the solar x-rays which were measured on the Command Service Module of Apollo 15 during its orbit around the Moon. In this way values for the Al/Si and Mg/Si ratios were obtained for large areas of the lunar surface.27 ...

This operation can induce extrinsic variability in agrochemical concentrations and fluxes in soils due to variability in application itself (random if broadcast nonrandom if banded) and the tillage operation. Weed scientists have examined such variability, in particular as related to herbicide efficacy ( 15 - 21 ). Such extrinsic variability in pesticide concentrations can also pose serious problems in obtaining representative soil samples for pesticide concentration determinations. 

The average soil sample is always taken from an area characterized by uniform cultivation (the same plant, fertilization, etc.). Smaller localities with considerably different soil characteristics are eliminated from sampling. The average area for taking one representative soil sample should be in the range 1 to 10 ha. Exceptions to this rule are areas contaminated during accidents. Surface and subsurface [5] sampling can be considered. 

Fraenzie, O., 1994. Representative soil sampling. In Markert, B. (Ed.), Environmental Sampling for Trace Analysis. VCH Publishers, Weinheim, pp. 305-320. 

Applying this soil remediation technology requires special expertise this chapter describes the technology and its applications, indicating the materials and decontamination methods that can be used and how the system should be initiated and controlled. It also specifies the samples that need to be taken in order to monitor the decontamination process. Before remediation can commence, however, it is first necessary to clarify where contamination is present in the area of soil concerned and in what form. It is furthermore necessary to perform electrokinetic laboratory tests with one or preferably more representative soil samples. Finally, it is explained how the data are analyzed and used for carrying out the design of the remediation system. 

Hvorslev (1949) classified soil samples as nonrepresentative, representative, or undisturbed. This classification is made by comparing the state of the sampled soil to that as exists in situ. A nonrepresentative sample is one in which soils from different strata have been mixed, or some of the soil constituents of the sampled soil are missing. Samples that contain scrapings from the well of the borehole or samples with some of the fine particles washed out during sampling fall in this category. A representative soil sample is one in which there is no change in soil constituents but whose structure, water content, or void ratio has been altered. An xmdisturbed sample, ideally, is one that represents the in situ condition. 

Soil particles differ widely in chemical composition, which introduces a degree of heterogeneity into the spatial distribution of minor components. Chemically reactive species become concentrated within smaller sized particles or associated with secondary surface coatings and must be considered with respect to the collection and preparation of truly representative soil samples. 

Soil testing (often called somewhat inappropriately analysis ) is a process of taking a representative soil sample from a field and testing it for available nutrients. From this test, expected yield, and prices, a recommen-dation is made of how much fertilizer should be applied to maximize the profit for the farmer. Although not an exact science, the process has proved its worth in the past 50 years. Soil testing becomes more important after fertilizers are used for some years since large differences in fertility between fields in an area will develop, and P and K levels increase in the soil. It is therefore veiy cost-effective to establish more accurately the necessary rates and monitor the soils for other potential problems. 

The XRD results of the 18 bulk samples suggest that the soil layers have similar mineral compositions, consisting mainly of clay minerals and quartz. The notable difference among the soil layers is the variations in relative proportion of these minerals, as suggested by their relative intensities in the XRD patterns. Figure 2 shows the XRD patterns of bulk sample and its clay separate of the representative soil sample from layer 14. It ean be seen from Figure 2 that clay minerals with 14—15, 10, and 7 A (001) spacings are present in the patterns. 

Most of the available methods to determine the in-situ density of material depend on the removal of a representative soil sample from the site and then determining the mass and volume it occupied before being removed. Mass determination is common to all methods and straightforward. The variation lies in the several procedures used for measuring the volume. Both ASTM and BS recommend the following methods, normally restricted to soil within 2 m of the surface and above groundwater level only ... 

Selection of Representative Soil Samples The representative sampling sites were chosen among all farms (around 4600) enrolled in Wine-Vine Register of the Modena district. Information about the total extension of the farms, their relative area in each municipality, and all... 

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