The outer bund of the Vaippinkadu Vadakku paddy polder in Pallippad breached following a rise in water level on Monday.
The entire harvest-ready crops in the 117-acre polder have been submerged resulting in losses to farmers.
Officials said that efforts were on to plug the breach and dewater the field. The field was to go under combine harvesters two days ago, but the harvest got delayed due to heavy downpours.
Meanwhile, the rain continued to lash parts of the district on Monday. Floodwaters entered several houses and low-lying areas remained waterlogged after heavy downpours hit Cherthala taluk.