Related על חלה 2:1

[If] a ship comes from outside the Land and had in it produce: from the string to the inside, if it is skimming [the sea floor], it is liable (see Gitt. 7b:7), according to the calculation, and [if its from the string to] the outside, [it is considered] outside the Land, and [the produce] is not liable according to the calculation. Rabbi Eliezer says, any amount of dust from the Land of Israel is liable according to the calculation.