Combine the given two facts to write a concluding fact. Note that there should be some parts of the first and second facts that are not mentioned in this conclusion fact. Your combined fact should be the result of a chain between the two facts. Chains form when two facts connect together to produce a concluding fact. An example of a chain is: "pesticides cause pollution" (fact1) + "pollution can harm animals" (fact2) → "pesticides can harm animals" (conclusion fact). Parts of the concluding fact overlap with the first and the second fact. To construct such a  concluding fact, a useful way is to borrow the subject from one fact and the ending conclusions from another fact.

Fact 1: the looseness of soil increases the amount of oxygen in that soil. 
Fact 2: Oxygen in the soil is vital for healthy roots.
Looseness of soil increases the odds of healthy roots.

Fact 1: dehydrating food is used for preserving food. 
Fact 2: Dehydration is the removal of water.
Removing water preserves food.

Fact 1: Weather refers to the conditions of the atmosphere from day to day. 
Fact 2: Variable weather conditions create atmosphere.

Weather refers to variable conditions day to day.