Comparison of Soil Properties in Different Fertilizer Input Systems in Lowland Rice at the Third Year in Transition

Abstract

Synthetic inorganic fertilizers (SIF) have the potential to impose detrimental environmental effects and are frequently utilized in Sri Lankan conventional rice farming. To maximize rice yield while maintaining soil health, soil nutrient management is vital. In this study, the soil properties of rice fields maintained using conventional (as recommended by the Department of Agriculture (DOA), 2013), reduced (50% DOA + 50% organic), and organic Input Management Systems (IMSs) were studied. The Rajarata University of Sri Lanka's Faculty of Agriculture established this experiment during the Maha season of 2020–2021 utilizing a Randomized Complete Block Design. At the initial, 50% flowering, and harvesting stages, soil samples were obtained from three distinct IMSs with three replicates at surface (0 - 15 cm) and subsurface (15 - 30 cm) soil depths. The data were analyzed using linear mixed effect models followed by Tukey's mean comparison. Three IMSs and three different stages of rice growth exhibited substantially varying soil pH, EC, available P, and exchangeable K values in this third transition year (p<0.05). Despite being highly varying across IMSs, soil CEC was not significantly different (p>0.05) among the stages of rice growth. Three IMSs' soil available N did not change significantly (p>0.05) yet differed across growth stages (p<0.05). In comparison to those obtained with conventional IMS, rice grain yield with organic IMS produced levels that were noticeably similar. The highest grain yield was produced with reduced IMS (p<0.05). This illustrates the possibility of boosting yields and sustaining soil fertility by substituting organic manure for 50% of SIF.