One-time root-zone nitrogen application increased wheat yield and nitrogen utilization under distinct planting row spacings in the Yangtze River Delta Region of China

Global evaluation of key factors influencing nitrogen fertilization efficiency in wheat: a recent meta-analysis (2000-2022)

“…In this study, the highest wheat yield increase (81.68%) was observed at 150-300 kg ha -1 and a respective decline in yield (70.7%) with further addition of N fertilizer beyond this threshold amount as shown in ( Figures 2 , 3A ). Previous studies reported that with N levels up to 225 kg ha -1 a noticeable increase in wheat ( Song et al., 2023 ) and maize ( Jiang et al., 2019 ) productivity was observed regardless of N application methods; however, as N levels beyond this point, yields began to decline. The decrease in crop production with higher N fertilizer addition over the recommended amount may be attributed to exceed crop nutrient requirements, oversaturating plant nutrient absorption systems ( Dobermann, 2005 ; Wang et al., 2011 ) and profoundly affecting the photosynthesis rate and grain filling potential in cereal crops thereby affecting grain yield.…”

“…Banding of N under inadequate soil moisture may affect the nutrient movement in soil and N uptake potential, which ultimately contributes to lower grain yield. Also, surface broadcasting increases the risk of N loss through volatilization and runoff, and reduces available N for plant uptake ( Song et al., 2023 ). However, the observed higher yield response with N incorporation is attributed to increased availability of N within the root zone and reduced leaching and run-offs, which thereby enhances N-uptake and grain yield.…”

“…As a result, over-application is becoming a common practice, particularly in countries like China that have a high level of intensive production systems ( Zhang et al., 2015 ; Jiang et al., 2019 ). However, excessive N application does not always translate into a continuous improvement in crop productivity, rather it leads to several environmental and ecological problems ( Zhang et al., 2012 ; Zhang et al., 2019 ; Song et al., 2023 ) such as air pollution, soil acidification, and eutrophication of water bodies ( Chen et al., 2014 ; Ren et al., 2022 ) and undermine the sustainability of food and energy production. Nevertheless, the optimum use of N fertilizer has been recognized as an important factor to maintain crop yield, minimizing ammonia (NH 3 ) losses and greenhouse gas (GHG) emissions ( Dungan et al., 2021 ).…”

“…However, some studies criticized that split application is not effective in increasing yield but rather exacerbates N losses. This is mainly because urea applied by this method may result in quick hydrolysis and then be prone to loss from the soil-plant system due to its distance from the root zone ( Irfan et al., 2021 ; Song et al., 2023 ).…”