On Mount Sinai, G-d communicates to Moses the laws of the Sabbatical year: every seventh year (known as ‘shmita’ - meaning ‘to release’), all work on the land should cease, and its produce becomes free for the taking for all. As soon as the Jewish people settled in the Holy Land, they began to count and observe seven-year cycles. The next shmita year will be in 5782 (2021/22).
The year-long break from working the land was a show of faith in Hashem and enabled focus on higher, more spiritual, pursuits of Torah study while shmita is followed. During shmita, the land is left to lie fallow and all agricultural activity (plowing, planting, pruning and harvesting) is forbidden. Watering, fertilizing, weeding, spraying, trimming and mowing may be performed as a preventive measure only, not to improve the growth of trees or other plants. Similarly for gardening, only actions for the immediate upkeep are permitted as opposed to those which enhance or improve the ground. Any fruits which grow of their own accord are deemed ‘hefker’ (ownerless) and may be picked by anyone. A variety of laws also apply to the sale, consumption and disposal of shmita produce.
The rabbis of the Talmud and later times interpreted the Shmita laws in various ways to ease the burden they created for farmers and the agricultural industry. The ‘heter mechira’ (sale permit), developed for the Shmita year of 1888/89, permitted Jewish farmers to sell their land to non-Jews so that they could continue to work the land as usual.
This temporary solution to the impoverishment of the Jewish settlement in those days was later adopted by the Chief Rabbinate of Israel as a permanent edict, but generates ongoing controversy in orthodoxy. Observance of the rules of shmita is voluntary so far as the civil government is concerned today. There is an interesting story about the 1950/1 shemita on an Israeli moshav which you can read at this link: www.tinyurl.com/shmita-story. Religious Authorities who prohibit farming during shmita in Israel generally permit hydroponics and farming in greenhouses where the plants are not connected to the soil, and so the produce is considered to be grown indoors. Crop rotation is recognised as fortifying the land against depletion of its minerals. An Israeli environmental blogger wrote: “Whenever we remind ourselves that this land, any land on earth, does not really belong to us, but is borrowed, we give it more reverence and respect.”