Individual and combined effect of p and k on yield and nutrient uptake of hybrid rice under IPNS in an alluvial soils of Assam

Abstract

A field experiment was conducted based on soil test crop response correlation in an Alluvial soils of Assam during Kharif season of 2016 - 17 following Ramamoorthy’s Inductive-cum-targeted yield model to elucidate the relationship between soil tests and response of hybrid rice ( cv US -382) to applied fertilizers under integrated plant nutrition system (IPNS). For producing one quintal of rice grain, hybrid rice required on an average 2.00, 0.31 and 2.35 kg N, P and K, respectively. The results also indicated that integrated application of chemical fertilizers and vermicompost increased the grain and straw yield, and NPK uptake in rice as well as enhanced organic-C and available N, P and K in soil. Omission of nutrients caused yield loss between 8.3 % (- P) and 9.7 % (- K) and it has also decreased their uptake. Conversely, plots receiving P and K fertilizers alone could significantly increase grain yield by 9.3 % and 5.2 %, respectively over control. The P and K uptake were increased by 35.8 % and 30.3 % respectively, over control due to individual addition of P and K with respective apparent recovery of 7.3 % and - 21 %. Uptake of all the nutrients was significantly correlated with yield (r= 0.840**, 0.373** and 0.284** for N, P and K, respectively), suggesting interdependence of nutrient uptake that influenced yield. Buildup of organic-C and available NPK was more pronounced in chemical fertilizer treated plots.