The chinampa…is anchored by roots of the ahuehuete tree and by posts and vine walls. Mud from the canals is piled up on a bed of wattles and vines, and layers of water weeds which serve as compost form the upper section of the plot. This is covered with a layer of fresh mud, which provides a fertile medium for planting. The chinampa plots are usually surrounded by an intricate network of canals. These canals are stocked with carp and other fish, and a giant salamander called axolotl, which is considered a delicacy. The canals also provide organic fertilizer and mulch in the form of abundant green algae which is skimmed off the water and applied to the plots….Human wastes were collected, treated, and recycled as fertilizer without polluting its indispensable canals. Urine was collected separately, broken down, and two of its by-products were paint and sulphate of ammonia. This was all part of a rhythm or recycling that had become as natural as breathing.
Jan Carew, Fulcrums of Change, 151-153