Harvest by a Jew in a heter mechirah field for agricultural experimentation
Question
I am a scientist at an agricultural research institute which performed heter mechirah. I would like to harvest samples of wheat planted during the shemitah year in the field sold through heter mechirah. Is it permissible for a Jew to harvest in this way, since it is not the regular method of harvest and in addition I do not intend to eat the wheat kernels?
Answer
In principle, ketzirah, grain harvest, is one of the four biblical actions (in addition to zeri’a (sowing seeds), zemira (pruning fruit trees or vines), and betzira (harvesting fruit)) that are forbidden to Jews even if heter mechirah was performed. It is permissible only for non-Jews.
Rambam (Shevi'it 4:1) writes: "The statement "Do not reap the aftergrowth of your harvest" means that one should not reap it in the same manner as one does every year. If one reaps it in the ordinary manner, he is liable to receive malkot (lashes). Examples of ‘regular’ reaping/harvesting include harvesting the entire field, piling up the grain, and threshing it with cattle or harvesting a crop for the sake of subsequently tilling the land... Instead, he should reap the land little by little, thresh the resulting (small amount of) grain, and partake of it."
By writing "he harvested the entire field," Rambam implies that the prohibition concerns harvesting in the usual manner, where large amounts are harvested, enough to "set up a grain heap" or to thresh with cattle. However, harvesting small amounts for immediate use and not for large-scale piling of grain for storage or threshing is not a biblical prohibition, but rather a rabbinic prohibition.
Small-scale grain harvest usually is forbidden rabbinically in a field that was sown during shemitah, but is permissible to be done by a Jew if the field was sold by heter mechirah.
Rabbi Shlomo Zalman Auerbach permits Jews to harvest on land sold to a non-Jew
Rabbi Yechiel Michel Tucazinsky in Sefer Hashemitah (II 9:2, pp. 102–104) writes that grain and grape harvest following heter mechirah is permissible by a Jew if performed with a shinuy, a different way than usual, since this attests that the produce is ownerless. He cites Rabbi Shlomo Zalman Auerbach's innovation in Ma'adanei Eretz (§2 in particular and §3–4): even though grain and grape harvest are biblical prohibitions, after heter mechirah only sowing and vineyard pruning are forbidden to Jews. However, grains and grapes (or any other fruit) are permitted to be harvested in the same way as in non-shemitah years since these acts are linked to ownership of the produce and the soil is sold to a non-Jew and thus is not holy. This is distinguished from sowing and pruning, which are independent of ownership but are forbidden acts in and of themselves, since it is forbidden for Jews to sow even in fields belonging to non-Jews in Eretz Yisrael. Thus it is permissible for a Jew to harvest the wheat of a non-Jew.
It should be noted that this general ruling is opposed to that of Rabbi Kook (Mishpat Kohen 67), who forbids Jews from participating in any grain or grape harvest under heter mechirah.
In conclusion: Taken together, it is permissible during shemitah to harvest small quantities of wheat grown on land that was properly sold to a non-Jew.