Effect of Tillage and Irrigation Interactions on Soil Water Dynamics, Root Growth and Water Use Efficiency of Wheat in the Indo-Gangetic Plain

Abstract

Field experiment was undertaken during the rabi seasons of 2015-16 and 2016-17 to study the effect of tillage and irrigation interaction on soil water dynamics, root growth, yield and water use efficiency (WUE) of wheat in a maize-wheat rotation in a sandy loam soil. The treatments comprised of three levels of tillage as main plot [Conventional tillage (CT), Deep tillage at the interval of two years (DT) and No tillage with maize residue @ 5 t ha-1 (NT)] and three levels of irrigation as sub-plot [I1: 1 irrigation (CRI), I2: 3 Irrigations (CRI, Tillering, Flowering) and I3: 5 Irrigations (CRI, Tillering, Jointing, Flowering, Milk)] were evaluated in a split plot design. Results showed that no tillage with residue (NT) treatment maintained higher soil moisture content in the surface layer (0-15 cm) than that of conventional tillage (CT) and deep tillage (DT) but in lower layers (45-120 cm), soil moisture content under DT was higher than that of NT and CT. Profile moisture storage at 0-120 cm soil depth was the highest under DT followed by NT and CT, respectively. In both the years, seasonal evapo-transpiration under DT was higher than that of CT, followed by NT. The root length density (RLD) under DT was significantly higher than that of NT and CT by 12.5 and 40.7 per cent, respectively at 0-15 cm soil depth. The RLD increased significantly with increasing irrigation level at 0-15 cm soil depth. Grain yield of wheat during high rainfall year (2016-17) was higher than that of low rainfall year (2015-16) by 39.2 per cent due to higher water availability, lower maximum air temperature and more bright sunshine hours received during that period. In both the years, there was no significant difference among tillage treatments with respect to grain yield of wheat but it increased significantly with irrigation. However, during the year 2015-16, there was no significant difference in the grain yield due to I2 and I3 whereas during the year 2016-17, there was no significant difference in the grain yield between I1 and I2 irrigation levels. There was no significant difference among tillage treatments with respect to WUE of wheat in year 2015-16 but during 2016-17, WUE of wheat under DT was significantly higher than NT. During the year 2015-16, WUE of wheat decreased with the increase in irrigation levels but during the year 2016-17, there was no significant difference among the irrigation treatments with respect to WUE of wheat.