Phosphorus Availability in the Rhizosphere Soil of Rice Hybrids as Influenced by Crop Manage- ment Options

摘要

Two field experiments were designed in the wetlands of Tamil Nadu Agricultural University, Coimbatore with two rice hybrids as CORH2 (125d) and ADTRH1 (115d) during wet season (Aug-Jan, 2001) and dry season (Mar-June, 2002) respectively, to study theeffect of modified crop management options on the availability of phosphorus in the rhizosphere soil. The treatments included planting of younger seedlings during the wet season and direct seeding during the dry season, water saving irrigation, weed management aided by in situ weed incorporation using conoweeder, green manuring along with chemical fertilizers verses conventional planting (transplanting), conventional irrigation, manual hand weeding and inorganic fertilization. The experiment was laid out in strip plot design with each treatment replicated four times. Phosphorus (P) in general is immobile in soil and is prone to fixation. Differential crop establishment, conoweeding and green manuring practices have improved the availability of phosphorus due to the increased root activity of the plants favouring the solubility and mobility of phosphorus. Limited irrigation did not bring out noteworthy impact on the availability of phosphorus.