Soil Test Based Fertilizer Calibrations in Pressmud Amended Rice-Wheat Sequence in Alluvial Soils of India

Abstract

A field experiment with a range of soil fertility and fertilizer regimes was conducted for two years on analluvial soil of Punjab state of India to develop fertilizer calibration relationshlps based on soil test for rice-wheat sequence amended with pressmud (PM), a sugarcane industry waste .. The nitrogen (N), phosphorus(P), and potassium (K) nutrient requirements and fractional contribution of the e nutrient from soil (CS),fertilizer (CF), and pressmud (C PM ) for meeting the nu trient needs of rice and wheat we re wo r ked outempirically by using appropriate sets of fertilizer , P, K and PM combinations. These parameters wereused to develop soil test and yield goal based fertilizer calibration linear relationshlps, which in turn wereused to develop q u ick-refe r ence guides for ascer t aining optimum fertilizer doses. Th ese fer t ilizerrecom m endations h ad high er site-specific character than the conve n tional soil test category based approachwhic h recomme n ded the same dose for a rang of soils. The calibration relationships allowed dynamicadjustment for changes in soil test st atus and organic amendme n t ra tes. The ready reckoners suggestedthat over a wide soil fertility range using the PM@ 5 t ha-1 before transplanting rice for attaining respectiveyield targets 7.0 t ha-1 and 5.0 t ha -1 of rice and wheat helped cut down fertilizer N, P, and K dose in rice by66-93%, 9-17%, and 30-40% and in wheat by 0-10%, 12-20 %, and 7-13% respectively. These savings not onlyhave the monetary significance but also imply concomitant environmental, food security, and sustainability benefits.