This is a type of farm that uses a rotation system for crops and fish ponds. Used in the central plains of Thailand, it is a classic example of regenerative farming. Two identical plots are used, each containing parallel ridges with water channels in between them. Higher ridges divide the two plots and surround them.
On the central ridge, a two-level pig and chicken house is built, with floors made of grating that allows excrement to drop from the bottom of the house into the plot that is being flooded for use as a fish pond. The chickens are on the top floor of this house. The pigs, which eat the chicken droppings, in turn pass their manure on to the fish pond.
The pig manure is not normally eaten directly by the fish, as its available energy and protein content are low. Instead, most of it sinks to the bottom, where it is used by phytoplankton and heterotrophic microorganisms, which are eaten by zooplankton. These, in turn, are eaten by the fish. In this process, various crucial nutrients are returned to the soil of the fish pond, which will finally be drained and used for crops next year. The lower channels will remain filled with water, which is excellent for irrigation and can still be used for some fish production. The second plot, of course, is flooded for use as a fish pond.
This integrated agriculture-aquaculture system is almost completely closed, with a very low operating cost to the owners and little harm to the land. While the yield of both crops and fish are low compared to standard monocultures and ponds fed with prepared feeding pellets, long-term ecological benefits and low operating costs offset this lower yield.