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.
The crops that we grow for food need specific conditions to thrive, including the right temperature and enough water. A changing climate could have both positive and negative effects on crops. For example, the northern parts of the United States have generally cool temperatures, so warmer weather could help certain crops grow. In southern areas where temperatures are already hot, even more heat could hurt crop growth. Global climate change will also affect agriculture and food supply in many other ways.