Variations in Soil Properties, Rhizome Yield and Quality as Influenced by Different Nutrient Management Schedules in Rainfed Ginger

Abstract

While there are numerous reports on nutrient management in ginger (Zingiber officinale Roscoe), a comprehensive study dealing with the simultaneous influence of different nutrient management schedules on ginger yield, rhizome quality, nutrient uptake (oleoresin, essential oil, essential oil constituents) and soil properties (physico-chemical and biochemical) is found wanting. Hence, field experiments were conducted between 2007 and 2016 involving (1) organic nutrient management (ONM) consisting of exclusive use of biological fertilizers, viz. Bacillus megaterium, Azospirillum lipoferum, farmyard manure, vermicompost, neem cake and ash, (2) chemical nutrient management (CNM) consisting of only inorganic sources of nutrients, viz. nitrogen, phosphorus and potassium applied @ 75–50–50 kg ha-1 in the form of urea, rock phosphate and muriate of potash, respectively, and (3) integrated nutrient management (INM) encompassing both organic sources and biological fertilizers, viz. FYM and N applied at 50% of CNM and P, K applied at 100% of CNM, i.e. 37.5–50–50 kg ha-1. The results on soil properties revealed that soil pH was lowest in CNM (5.03), while soil organic carbon (SOC) level was markedly higher by 39.0% in ONM and by 32.8% in INM compared with CNM. Bray P level was greater in ONM by 119.0% compared with CNM and by 72.0% compared with INM. Exchangeable Ca and Mg were greater in ONM and INM, and among available micronutrients, available Cu and Fe levels were greatest in ONM and available Mn level was greatest in CNM. Among the soil biochemical parameters, microbial biomass C increased markedly by 81.0% in ONM and 48.0% in INM. This was responsible for enhanced b-glucosidase, acid phosphatase and dehydrogenase activities in ONM and INM, though urease activity was greatest in CNM. In case of rhizome yield, CNM registered significantly lower yield (mean 11.14 Mg ha-1) in comparison with ONM and INM (mean 18.64 and 18.50 Mg ha-1, respectively) across all the years. With regard to rhizome quality, the essential oil content in ONM and CNM was almost identical (1.0–1.7%), while it was slightly higher at 1.32–4.0% in INM. Results on rhizome oil components showed that pinene, d-camphene and b-phellandrene contents were higher in CNM, b-citral (neral) and citronellol in ONM and a-citral (geranial) in INM. The study, in general, indicated the distinct possibility of reducing or avoiding application of chemical fertilizers while simultaneously sustaining ginger rhizome yield and quality through ONM or INM.