Another way to collect a stool sample is to loosely place plastic wrap across the rim of the toilet, under the seat. Then place the stool sample in a clean, sealable container before taking to the laboratory. Plastic wrap can also be used to line the diaper of an infant or toddler who is not yet using the toilet. The stool should be collected into clean, dry plastic jars with screw-cap lids.
The potential variations in the properties of agricul-. tural soils are less well known. Diaz et al. (1994) have. reported that under a climate change scenario the soil. organic matter content and erosion rate would de-. crease with regard to current values in the Arrecifes. River basin.
Pesticides and pollution of the soil First, affect soil quality. Decrease biodiversity in the soil because they do not just kill the intended pest; they often kill many of the other small organisms present. Soil quality deteriorates and this has a knock-on effect upon the retention of water. Soil fertility is affected too. When pesticides kill off most of the active soil organisms, the complex interactions which result in good fertility break down. Plants depend on millions of bacteria and fungi to bring