During Polk's term declining agricultural yields due to worn out soil were a matter of great concern. To address the concern, the Delaware General Assembly hired an expert from the Franklin Institute in Philadelphia, who provided a good deal of helpful advice on the use of fertilizers. As it happened, the construction of the Chesapeake and Delaware Canal was beginning, and some farmers in New Castle County realized the marl obtained from the dredging would enrich their soil. Using this soil, the first peach trees were planted near Delaware City.