Integrated nutrient management in taro in relation to nutrient dynamics and fractionation of major nutrients in an Alfisol of Eastern India

Abstract

Taro (Colocasia esculenta L.) is an important tropical tuber crop widely grown in many locations of northeastern India particularly due to the popular use of both its leaves and cormels as a traditional food. Moreover, the nutritive significance of the crop with respect to many valuable phytochemicals too helped in the widespread cultivation of this crop in these areas. The integrated nutrient management strategy for the crop is standardised and efforts were made to determine the different organic and inorganic fractions of the major nutrients under different combinations of nutrients on the yieldand proximate composition of the cormels. Hence, field experiments were conducted for two kharif seasons during 2018-2020 with 14 treatments replicated thrice in RBD in an Alfisol of eastern India. The soil of the experimental site is Typic Haplaqualf, which is slightly acidic, non-saline, very low in organic carbon (0.20%), and medium in available P and K. The effect of the treatments revealed that the inorganic fractions and available N, P and K contents were highest under integrated application of FYM along with half the recommended dose of N:P:K @ 40:15:40 kg ha-1 followed by application of chemical fertilizer alone as N:P:K @ 80:30:80 kg ha-1. Available N in the soil was contributed mostly by NO3-N and transformation of total N into inorganic fractions. The available P fractions occurred as reductant soluble P (42.39 mg kg-1) > Fe-P (38.10 mg kg-1) > Ca-P (30.23 mg kg-1) > Al-P (23.71 mg kg-1) > Bray’s-1-P (17.86 mg kg-1) > water soluble P (2.94 mg kg-1). All the inorganic P fractions contributed significantly to the available P pool and the correlation coefficient (r2) wasfound in the order of water soluble P (0.97**) > Fe-P (0.96**) > RS-P (0.95**) > Al-P (0.94**) > Ca-P (0.90**). Occurrence of different K fractions was in the order of NH4OAc-K (210.05 kg ha-1) > exchangeable-K (186.56 kg ha-1) > non-exchangeable K (111.54 kg ha-1) > water soluble-K (23.49 kg ha-1). However, exchangeable K and total K contributed significantly towards the available K content of the soil. Ammoniacal N showed highly positive and significant relationship with corm yield and biochemical constituents. Iron bound P and Al-P fractions contributed mostly towards the P nutrition of taro as these two fractions showed highly positive and significant correlation with yield and proximate composition. Of all the K fractions, non-exchangeable K recorded higher ‘r’ values for corm yield and biochemical constituents of taro. Integrated application of FYM and half the recommended dose of NPK not only enhanced the yield and quality of cormels and sustained the soil quality, but also influenced the NPK transformations for plant uptake in Alfisols.Keywords : Integrated nutrient management, Organic manures, Inorganic fertilizers, Taro, NPK fractions