Effect of integrated nitrogen management through organic and inorganic sources on the yield of rice ( Oryza sativa L.) and status of soil fertility at harvest Harish Shenoy* Department of Botany, University College, Mangalore, Mangalore University, Mangalore - 575001 (Karnataka), India. Siddaraju. M. N. Department of Botany, University College, Mangalore, Mangalore University, Mangalore - 575001 (Karnataka), India. *Corresponding author. Email: harish.shenoy1@gmail.com Article Info https://doi.org/10.31018/ jans.v12i4.2433 Received: November 4, 2020 Revised: December 11, 2020 Accepted: December 14, 2020 How to Cite Shenoy H. and Siddaraju. M. N. (2020). Effect of integrated nitrogen management through organic and inorganic sources on the yield of rice (Oryza sativa L.) and status of soil fertility at harvest . Journal of Applied and Natural Science, 12(4): 721 - 727. https://doi.org/10.31018/jans.v12i4.2433 This work is licensed under Attribution-Non Commercial 4.0 International (CC BY-NC 4.0). © : Author (s). Publishing rights @ ANSF. 721 - 727 Published online: December 15, 2020 ISSN : 0974-9411 (Print), 2231-5209 (Online) journals.ansfoundation.org Research Article INTRODUCTION Rice (Oryza sativa L ) is one of the important cereal crops of the world occupying 11% of the agricultural land and ranks second in terms of cultivated area (Tumrani et al., 2015). Globally rice is grown on an area of 162 million ha with a production of 461 million tons and productivity is 4.09 tons per ha (Anonymous, 2015). Rice is life for almost half of the global popula- tion and the majority of the Indian people. The living and livelihood of the majority of the Indian farming population also depend on growing rice. In India, the rice is grown in an area of 43.19 million ha with a pro- duction of 110.15 million tons. (Anonymous, 2017). Rice production in India has increased almost three- fold over the last five decades and contributes hand- somely to the nutritional security of the country. Though rice production continues to play a vital role in the national food and livelihood security of the Indian system, the productivity of rice is only 2.55 t/ha (milled rice) which is less compared to global productivity of 3.28 t/ha (Anonymous,2018). The growing population demands a reorientation of the research efforts in rice-based agricultural produc- tion systems to ensure higher productivity with less land, less water, and less labour, with environment - friendly technologies that are more resilient to climate change and minimize environmental footprints. In- creasing the productivity of rice remains the main challenge considering that 90% of the cultivated area of rice belong to small and marginal farmers. The most feasible way by which this could be achieved is by adopting a more integrated approach involving wa- ter, nutrients and other agronomic factors for maximiz- ing the rice grain yield (Gobi et al., 2016). Fertilizers have contributed substantially to nearly 50% of rice Abstract The present investigation was conducted with the objective of utilizing locally available organic resources for substituting chemi- cal fertilizer nitrogen partly and augmenting soil health. The experiment was carried out for the crop kharif rice (Oryza sativa L.) in coastal Karnataka with eleven treatments laid out in randomized block design with three replications. Vermicompost (VC), Poultry manure (PM) and Fish manure (FM) were used as organic nitrogen sources integrated with mineral nitrogen source of fertilizer urea at substitution ratios of 25, 50 and 100 percent. These treatments were compared with control and recommended dose of nitrogen. The results revealed that the substitution of 50 per cent of nitrogen through VC recorded significantly (P<0.05) higher plant height (92.27 cm), higher number of productive tillers (16.85 hill -1 ), higher grain yield (5434 kg ha -1 ) and straw yield ( 6817 kg ha -1 ) compared to control. The results of the soil sample analysis for soil fertility parameters indicated that the major nutrients were significantly (P<0.05) influenced by integrated nitrogen management. The available nitrogen (382.36 kg ha -1 ) and available potassium (143.7 kg ha -1 ) were significantly (P<0.05) higher in the treatment T4 where a recommended dose of nitrogen was substituted by 50 percent VC compared to control (294.05 kg ha -1 and 92.31 kg ha -1 respectively). However, the available soil phosphorus was significantly higher with treatment 50 per cent RDN substituted by PM (78.83 kg ha -1 ) as com- pared to control (43.93 kg ha -1 ). Thus, integrated resource management improved crop yield and post -harvest soil fertility. Keywords: Fish manure, Poultry manure, Rice, Soil Fertility, Vermicompost