Effect of tillage and irrigation regimes on soil physical properties and performance of sunflower in rice fallow I. Soil physical properties and crop establishment

Studies were conducted on a sandy clay loam soil (Typic Haplustalf) to evaluate the influence of five different tillage practices and four irrigation regimes viz, 60 mm irrigation at IW/CPE = 0.6, 0.8, 1.0 and 1.2 and their interactive effect on soil physical properties and performance of sunflower (Helianthus annuus L.) under rice fallow condition. The soil physical properties measured were; change in clod tillage depth, mean weight diameter (MWD) of dry clods, dry bulk density, penetration resistance and soil moisture contents. Primary tillage with tractor-drawn MB plough or tractor-drawn disc plough caused 26 cm deep tillage and significantly reduced soil dry bulk density and penetration resistance up to 30 cm soil depth. Tillage with bullock-drawn desi plough resulted in shallow tillage (11 cm) and influenced these properties only up to upper 15 cm. Secondary tillage with rotavator, either power tiller or tractor-drawn, made finer tilth measuring low MWD of dry clods and recorded significantly higher seedling emergence (80.7%). Speed of emergence (SOE), emergence rate index (ERI) and relative emergence (RE) of sunflower seedlings were found higher, while the mean emergence period was lower when secondary tillage was carried out with rotavator. Irrigation regimes caused significant changes only in soil penetration resistance, which was reduced with intensity of irrigation. Most conducive soil physical environment for sunflower after puddled transplanted rice was achieved by one passage of tractor-drawn disc/MB plough + one passage of tractor-drawn rotavator. Two passages of bullock-drawn desi plough + power tiller drawn rotavator also made conducive soil physical properties only up to 11 cm soil depth.