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36. Composting is the process of breaking down organic materials under controlled conditions. A student set up three compost bins, one of which is shown in Figure 20-6. Into each compost bin, he added an identical combination of wood shavings, shredded paper, nitrogen, and bacteria. He mixed the materials in each bin and adjusted the insulation around the bins to maintain daily target temperatures. He then monitored the temperature, moisture, and amount of decomposition of the compost in each bin over an eight-week period. Some of his data are shown in the graph.



At the end of eight weeks, the student found that the materials in compost bin A had undergone the most decomposition. The materials in compost bin B had decomposed the least. Use the graph in Figure 20–6 to explain these results.