Answer:
Surface Horizon (A)
Nutrient depletion of soils is a widespread soil degradation phenomenon that occurs as a consequence of soil erosion<u> (it is the topsoil in which generally most soil nutrients are present that erodes fastest) </u>but also because of poor management practices, such as slash and burn and other subsistence agricultural.
Answer:
Today most people in developed countries have a scarcity of food sources.
Having one theory is setting a limit on your potential and the potential of the overall theory and subject you are working on. Having multiple theories gives you a broader idea and perspective of what is going on, and even though one may slightly contradict the other, it is okay because that is what theories are for.
To the point, scientists usually have more than one theory so that they can gain a broader perspective on the matter and maybe even increase the chance of being correct on the matter.
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Hag Fish and Lamprey
Vertebrates are the organism which posses a vertibral column(aka the spine or back bone structure), while the earliest had a head they lacked a spine and jaw, these jawless vertebrae lived 500-600 million years ago. they are the ancestors of bony fish which in time became amphibians and other groups of animals
1,000 years
In many parts of the world, trees can provide a climate history for hundreds of years, with some extending back 1,000 years or more.