Ridge-furrow film mulch with nitrogen fertilization improves grain yield of dryland maize by promoting root growth, plant nitrogen uptake and remobilization

Soil mulch has been widely applied to enhance crop yields in (semi-)arid and semi-humid regions on the globe. However, how different mulch practices influence root growth, plant nitrogen (N) uptake, remobilization and allocation remains unclear, especially under different N fertilization rates. A two-season (June–October in 2021 and 2022) field experiment was performed on dryland summer maize in a semi-humid but drought-prone region of northwest China. There were six mulch practices: flat cultivation without mulch (Flat), flat cultivation with straw mulch (Flat-Straw), flat cultivation with black film mulch (Flat-Film), flat cultivation with transparent film mulch (Flat-Trans), ridge-furrow cultivation with black film mulch on the ridge (Ridge-Film), ridge-furrow cultivation with transparent film mulch on the ridge (Ridge-Trans), and two N fertilization rates: 0 kg N ha−1 (N0) and 180 kg N ha−1 (N1). The results showed that film mulch significantly (p Flat-Straw. The Ridge-Film with N fertilization significantly (p