Sampling - Field Sampling: Principles and Practices in Environmental Analysis - page 131

FIGURE 5.12 A pasture field with cows.
and so on are applied. In some cases, organic additions are applied, often in the form of
animal manures, and these add not only plant nutrients, but also organic matter,
microorganisms, and antibiotics given to farm animals. Table 5.2 gives estimates of the
amounts of some amendments commonly added to agricultural fields.
5.12.3. Geological Sampling
Rock frequently has horizons that are horizontal, much like those in soil. Because of
upthrusting of rock layers and intrusion of lava or a different rock layer into an already
existing rock, however, there may also be layers that are not horizontal, and their slopes
vary from 0° to 90°. An intrusion of one rock into another is shown in Figure 5.13. Thus,
it is possible to need to sample a layer that is vertical. In this case, a vertical sample may
extend for considerable depth and the same material is sampled through the length of the
sampler. It may be equally important in this case to sample adjacent rock vertically as
well; however, the horizons in the adjacent rock may be horizontal and thus require an
entirely different sampling procedure. A rock having horizontal layers is shown in Figure
5.14.
With steeply sloping layers, it is necessary to change sampling depth across the
sampled area. It will be essential to have some identifying characteristic that will show
the persons sampling that they are in the correct layer. A detailed record of the sampling
depth across such an area is essential.