(Mishnah): If a sharecropper (working in Chakirus) received a field for less than 7 years, he should not plant in it flax and the sharecropper has no claim on the branches.

If he received it for 7 years, in the first year he may plant flax and he has a claim on the branches.

(Gemara) - question: It is understandable that if he took it to plant wheat, he should not plant flax; but to plant flax, why not plant wheat? (In only one year of planting), flax ruins the earth for 3 years and you say that this is permitted?!

R. Menachem, brother of R. Gurion explained before R. Ila - It is better to plant flax after flax than to plant barley after barley (and certainly wheat after wheat. Here, he had planted flax the previous year so the most minimal damage after that would be to plant flax again.)