Tillage management for efficient water and nitrogen use in wheat following rice

Abstract

Puddling coarse-textured soils in rice culture induces high bulk density in subsurface layers which impedes root growth of the subsequent crop(s) and causes nutrient and water stresses. These stresses can be alleviated by enhancing root development and/or regulating nutrient and water supplies. We evaluated the interactive effects of tillage, irrigation and N-rates on root growth, leaf area development, water use and yield of wheat following rice on a sandy loam soil. A 3-year study included combinations of three tillage systems without residues (no-till (NT), direct seeding; conventional till (CT), disrupting the soil to a depth of 10 cm; and deep-till (DT), subsoiling with a single tine chisel to a depth of 35–40 cm in 40-cm row width followed by CT); three irrigation regimes (75 mm irrigation at 125 mm net evaporation (I 1), at 83 mm net evaporation (I 2) and at 62 mm net evaporation (I 3) from class A pan); and four N-rates (0, 50, 100 and 150 kg ha −1). A fourth year experiment was conducted to validate regression models based on information from the first 3 years. Tillage and irrigation combinations were kept in the main plots and N-rates in the subplots in a split-plot design. Compared with NT, both CT and DT increased the depth and density of rooting, leaf area index (LAI), duration of green leaf area (LAD) and grain yield. Tillage increased the evapotranspiration (ET) and transpiration (T) component of ET. Yield responses to applied N were influenced by tillage and irrigation regimes. Computed yields from regression models, relating yield with water supply and N rates in NT and CT, agreed well with the independent data. For a given yield level, higher inputs of water and N were required in NT than in CT. Energy-use efficiency was also greater in CT than in NT.