Evaluating hydrogel application on soil water availability and crop productivity in semiarid tropical red soil

Abstract

The insufficient root zone soil moisture is the most important limitation for crop productivity on light texture soils of semiarid and arid regions. Application of super absorbent polymers in to the soil could be one of effective means to increase water use efficiency in crops. Laboratory and field investigations were carried out to evaluate the water retention and release characteristics of hydrogels and to evaluate its effect on crop productivity during kharif and rabi seasons in semiarid red soils. Overall, the amount of water absorbed by one gram of polymer ranged between 332 and 465 g (in distilled water) and about 91-96% of absorbed water was released within 15 bar tension i.e., permanent wilting point. Hydrogel was not found effective for groundnut and pigeonpea crop during kharif season but showed positive effect on tomato when it was tested @ 25-100 kg/ha. The agronomic efficiency of polymers application for tomato was highest when polymers were applied @ 50 kg/ha and it was 58 kg tomato fruit per kg of polymer application. In case of tomato grown during rabi season, it was observed that at least one irrigation in every three weeks can be postponed by applying polymers. This helped in recording the water productivity to the extent of 279 kg/ha mm and saved 210 ha mm irrigation water in entire crop growth period.