Whether or not you would consider this as scientific evidence, we only have to look at recent history to find an answer.
The Dust bowl of the 1930's came about because the land was continuously farmed, and the nutrients of the land were depleted to a point that it could no longer support vegetation.
All things need to have their nutrients renewed periodically This is true of the land as well as mankind. Since the Dust bowl farmers routinely allow a portion of their land to go fallow, usually on a field rotational basis. Many even grow crops that leave a residue to be worked back into the ground, such as soy beans and corn.
God in his infinite wisdom knew that anything material would, through the process of aging, deteriorate, and that occasional renewing by the input of new nutrients would be necessary. The renewing of nutrients slows the process of deterioration, whether it is in man or plants or animals or even the land. And that is the reason for God declaring the Sabbath year.
That is also the reason why fertilization is such a necessary component of growing plants whether in your flower garden or on a large farm.
That is incidentally the reason for his declaring a Sabbath day for man.
Exodus 20:8 KJV Remember the Sabbath day, to keep it holy.
God knew that unless man's awareness of him and his laws was renewed on a frequent basis it would eventually fade from his memory, as we see the World today.
When God put man into the garden of Eden he charged him with caring for it:
Genesis 2:15 And the LORD God took the man, and put him into the garden of Eden to dress it and to keep it.
This alone tells me that nature and the land needs our attention, but even further when God ejected man from the garden of Eden he told Adam that his punishment would be:
Genesis 3:17 through 19 And unto Adam he said, Because thou hast hearkened unto the voice of thy wife, and hast eaten of the tree, of which I commanded thee, saying, Thou shalt not eat of it: cursed is the ground for thy sake; in sorrow shalt thou eat of it all the days of thy life; Thorns also and thistles shall it bring forth to thee; and thou shalt eat the herb of the field; In the sweat of thy face shalt thou eat bread, till thou return unto the ground; for out of it wast thou taken: for dust thou art, and unto dust shalt thou return.
Genesis 3:23 Therefore the LORD God sent him forth from the garden of Eden, to till the ground from whence he was taken.
Since man is essentially dust and needs to replenish himself through eating why would the land be any different?