Making the world better, one answer at a time. Rich soil is made up of sand, silt, clay and organic matter (compost) in various stages of decomposition. Humus is the stable remains of decayed organic matter, carbon remains of unknown sorts that attach themselves to clay to improve soil structure. Humus has the ability to increase the soil's water retention, buffer PH , and helps the plant use nutrients although humus is not fertilizer but humic acids and humins.
Diseases carried by rats include, but are not limited too, the following: Bubonic plague â Rats are the primary source of plague infection in human populations. This horrific disease is spread to humans from rats by fleas. It's present in rodents throughout the western United States, and in many other parts of the world (see map).
This was not so. The plague was caused by disease-carrying fleas carried on the bodies of rats. A pair of rats in the perfect environment could breed many off-spring. The filth found in the streets of London provided the perfect environment for rats.