Water, the most crucial resource for sustainable agricultural production in the dry land/rain fed areas, is not being used fully. Much of the rainfall runs off the ground. The runoff does not only causes loss of water but it also washes away precious top soil.
Thus the concept of Farm Pond came up.
Farm Pond is a dug out structure with definite shape and size having proper inlet and outlet structures for collecting the surface runoff flowing from the farm area. It is one of the most important rain water harvesting structures constructed at the lowest portion of the farm area. The stored water must be used for irrigation only. Inadvertently, some people use the farm ponds as ground water recharge structures which is not correct as per the definition. For recharging the ground water, the structures require high capacity and are generally located in the soils having high infiltration rates and are called percolation tanks. Percolation tank is meant for only recharge purpose and not for irrigation. Such structures conceptually differ in their hydrology and physical location. A farm pond must be located within a farm drawing the maximum runoff possible in a given rainfall event. A percolation pond can be dug out in any area where the land is not utilized for agriculture.
The ideal farm pond should be dug into the ground in a naturally low-lying area. Some of the soil that is removed can be used to construct an earthen berm around the pond, which should be planted with trees and grasses for stability. The shade and wind protection provided by the raised mound and vegetation will reduce evaporative losses.
Greater depth of the pond and less surface area will also reduce evaporative losses. However, digging deeper than 5 meters will increase the expense of the digging, and increase seepage loss due to increased water pressure on the ground.
Farm ponds can be designed for three strategies of irrigation in rainfed regions as given below:
• Meeting the crop water requirement of growing season
• Meeting water requirement of critical irrigation(CRI) during the critical stages of crop growth
• Meeting water requirement in cropping system approach( Irrigation during critical stages of kharif crop plus the water requirement of rabi vegetable).