Answer:
Because they don't have fertilizer.
Explanation:
Well, if this was a long time ago, then farmers did not have fertilizer. So, there are bacteria on the roots of plants that convert nitrogen into a usable form. It's very important for growing, and when farmers harvest the crop, not much of the nitrogen is returned to the land, so it is not as fertile. Fertilizer is largely consisted of nitrogen, so that is why farmers use fertilizers today. But "a long time ago," farmers did not have fertilizer.
Answer:
One of water's important properties is that it is composed of polar molecules: the hydrogen and oxygen within water molecules (H2O) form polar covalent bonds.
Explanation:
<span>well i take this test before and the correct answer is :A They produce food by photosynthesis</span>
Some isotopes, however, decay slowly, and several of these are used as geologic clocks. Dating rocks by these radioactive timekeepers is simple in theory, but the laboratory procedures are complex. <span>All methods rely on the fact that certain elements (particularly uranium and potassium) contain a number of different isotopes whose half-life is exactly known and therefore the relative concentrations of these isotopes within a rock or mineral can measure the age.</span>
