Split application of ureapolyacrylamide for enhancing nitrogen use efficiency in Rice–Maize system

Abstract An unreasonable application of nitrogen (N) fertiliser leads to increased agricultural greenhouse gas emissions and unbalancing the soil ecosystem. To solve this, synthesize a slow-release N fertilisers with urea (U) and polyacrylamide (PAM) through polymerisation under specific conditions is ureapolyacrylamide (UPAM). After polymerisation, UPAM can be designed into four grades with respective carbon (C) and N concentrations (UPAM-1: N-32 & C-35%; UPAM-2: N-27 & C-39%; UPAM-3: N-25 & C-41%; UPAM-4: N-23 & C-42%). In order to ascertain the impact of various grades UPAM on rice and maize growth, yield, nutrient uptake and nitrogen use efficiency (N-UE). A two-year field (2020-21 & 2021-22) experiment laid out in a randomized block design (RBD) with three replications and ten treatments consisting of the following T1-absolute control, T2-UPAM-1, T3-UPAM-2, T4-UPAM-3, T5-UPAM-4, T6-UPAM-1, T7-UPAM-2, T8-UPAM-3, T9-UPAM-4 and T10-neem coated urea (NCU), was conducted on an agricultural farm at the IAS, BHU, Varanasi, (middle Gangetic plains) India. The main of the study was to investigate the leverage of various grades of UPAM application on soil physico-chemical properties, yield, nutrient content, nutrient uptake, and economic analysis of rice and maize. Our research findings evidence for the positive impacts of UPAM on yield and, nutrient uptake and maximum values were observed in plots treated with UPAM-2 grade followed by UPAM-1 and NCU, with a significant impact on soil available N content at different phenological growth stages, and non-significant impact on soil properties of both crops. Comprehensive analysis showed that UPAM-2 is a sustainable N fertiliser that helps to enhance the N availability, and sustainability in crop production.