Effect of Neem Oil Coated and Common Urea with Different Nitrogen Levels on Rice Yield and Nitrogen Use Efficiency (NUE) in Kaski, Nepal

Abstract

Rice is the most important staple food crop and plays a vital role in ensuring national food security in Nepal. Rice yield is largely determined by nitrogen management strategy and improving the effectiveness of nitrogenous fertilizer for grain production has long been a challenge. A field experiment was conducted in the sandy loam soil of Lumle, Kaski, Nepal in 2019 and 2020 to assess the effect of neem oil-coated urea (NCU) and common urea (CU) with varying levels of nitrogen (N) on rice yield and nitrogen use efficiency (NUE). The experiment with 7 treatments comprising the combinations of two types of nitrogen source (CU and NCU), three N levels (50, 100, and 150 kg/ha) and one control treatment without N, were allocated in a randomized complete block design with three replications. Increased nitrogen rates up to 100 kg/ha supplied through NCU significantly improved grain yield, yield components, and nitrogen use efficiency of rice. Application of NCU reduced nitrogen fertilizer use by up to 33 % while producing maximum yield and significantly increased agronomic nitrogen use efficiency (ANUE) and nitrogen partial factor productivity (NPFP) compared with CU. This suggests that the use of NCU with an optimum rate can be a viable option for appropriate N management in rice production.