Zeolite as a component of INM in enhancing nutrient mineralization and enzyme activities in an Ultisol

Abstract

AbstractIn modern agricultural practices, there is a growing interest to optimize fertilizer usage to improve crop productivity and minimize environmental impact with special emphasis on soil carbon. In this study, the effect of slow-release fertilization characteristics of zeolites on soil carbon mineralization, enzyme activities and available NPK contents were investigated. A three month period incubation study at ambient temperature and constant soil moisture conditions was conducted in laterite soil with 27 treatments consisting of three commonly available organic manures (farm yard manure (FYM), vermi compost (VC), leaf manure (LM) and three different levels of near neutral zeolites, specifically the grade Zeolite 4A (@ 0, 1 and 2%, w/w) and fertilizer doses (@ 100% NPK, 75% NPK and 50% NPK corresponds to cassava crop with a recommended dose of 100:50:100 kg NPK per hectare). Addition of NPK fertilizers from 50% to 100% decreased the mean carbon mineralization activity and increasing levels of zeolites from 1% to 2% increased the carbon mineralization rates (3.39 as against 6.64 g CO2 per kg soil). Among the organic manures, leaf manure had higher carbon mineralization rate (5.70 g CO2 per kg soil). The NPK @ 50% and 2% zeolite treated soils under vermi compost showed maximum activity of soil dehydrogenases (up to 42.99 ?g TPF g-1 24 h-1). Fertilizer and zeolite at 75% NPK and 1% doses respectively, registered the maximum acid phosphatase activity (1.258 ?g pnp g-1h-1). NPK fertilizers additions from 50% to 100% increased the soil available nitrogen content (127.97 to 136.67 kg ha-1). Maximum content of mean available K was found with 50% NPK and 1% zeolite treatments.Keywords: Zeolites, Carbon mineralization, Soil dehydrogenases, Organic manures