The flat reclaimed areas consist of fertile organic soil, ideal for growing crops such as onions, leafy greens, celery and carrots.
Organic matter improves the physical condition of soil, and residues from its decomposition play an important role in holding plant nutrients and water.
Submerged decayed trees contribute highly to the valuable fibrous nature of the soil, but without human assistance and ingenuity, the area would have little fertility.
In the 1920s the main crops reflected eastern and western European tastes - yellow onions, potatoes, carrots, head lettuce, radish, etc.
With the opening of Highway 400 in the 1950s, farmers quickly gained access to the Ontario Food Terminal in Toronto, vastly expanding their market.
[5] The southernmost polder sits on the lowest lying, flat area, consisting of 7,200 acres (29 km2), of the 816,120-acre (3,303 km2) Lake Simcoe Watershed region.
[citation needed] Before its development, the entire area was a large wetland extending almost continuously along the western arm of the Holland River.
Horses were ferried by flat-bottomed scows across flooded areas, wearing large boards on their hooves so as not to sink into the soggy ground.
[6] In October 1954, Hurricane Hazel overwhelmed the polder's drainage system with unprecedented heavy rains, resulting in the dykes being breached at the north canal.
[citation needed] Professor William Day led the project to reclaim the large southernmost Holland Marsh polder, which was completed in 1930.