Theme 1-9-Effective and safe surface rain water management for reclamation and crop production in black alkali soil

Abstract

A field experiment was planned and designed for in-situ water harvesting of surface water in black alkali soil during the year 1994 with the objectives of surface water harvesting, recycling, reclamation and crop production. The experiment was carried out for three years (1994-96) under rainfed condition with only in-situ water retaining technique by adopting raised and sunken bed system. After considering all the inflow and outflow parameters, crop requirement and crop adoption, a design of raised and sunken bed in ratio of 1:1 with vertical difference of 40 cm was considered appropriate on the basis of technical inputs. The crop selected on the basis of local climate was cotton (on raised beds) and paddy (in sunken beds). Apart from water harvesting and its recycling the in-situ retaining of water was necessary for effective and rapid reclamation of such soils. The initial three years result indicated that although the design was appropriate to retain rain water in the field but however it has some practical difficulty like at-least two events of heavy storms in all the three years caused runoff from the field and one or two long dry spell causing reduction in crop yield. These two events forced to an alternate ex-situ arrangement of a small water harvesting tank for storing some runoff water during heavy events and also sufficient for one irrigation to the crop during stress. The runoff of the field was collected in storage tank and was recycled during either stress or at recession of monsoon. The supply of one or two irrigation to the crop led two to three fold increase in yield during latter periods (1997-1998) of experiments and it also helped in increasing crop duration of paddy (from 90 to 110 days) and cotton (from130 to 150 days). The storage of water in sunken bed also helped in reducing the soil ESP to a great extent and shifting of soil from sunken bed to raised bed facilitated mixing of gypsum to a grater depth (0 to 40 cm) in raised beds. It can be concluded from five years of experiment that surface water can be utilized effectively for reclamation as well as crop production during Kharif season if raised and sunken bed system supplemented with a small storage tank is adopted. The ratio of raised and sunken bed and size of tank may be adjusted for other locality looking to the runoff potential of soil and rainfall of the area.