HaShem blessed Yitzchak in the land of the Plishtim. Yitzchak was very kind and gave one tenth of his proceeds to the poor. Hashem in turn rewarded him with over 100 times the normal produce!
Despite the year of drought and the fact that the soil was bad, everyone witnessed the incredible blessing Yitzchak received from HaShem. Actually, the Plishtim were quite jealous.