Abstract
The proper promotion of a deep root system is important for maize cultivation to improve water use efficiency in the arid and semi-arid Loess Plateau. Here, a field experiment was conducted to assess the effect of combined controlled release urea and normal urea on root growth and water extraction of maize in dryland fields. Maize in the combined controlled release urea and normal urea treatment had greater root systems compared to those in the normal urea treatment and no N application treatment. Compared to the urea treatment, combined controlled release urea and normal urea advanced the root length density and root weight density in the 0–10 cm soil layer at R1 stage by 30.99% and 45.03% in 2016 and by 20.54% and 19.13% in 2017. The root length density also increased at the dent stage (R5) by 52.05% and 47.75% in 2016 and 2017, and root weight density increased by 19.58% in 2016. Combined controlled release urea and normal urea promoted production of fine roots and root distribution, as well as decreased soil water storage (SWS) in the deep soil layer at the R5 stage. The grain yield was positively correlated with root length density and root weight density in the topsoil layer at the silking stage (R1) and in the whole soil profile at the R5 stage, suggesting that better root system management is helpful for increasing crop grain yield. Therefore, this work demonstrates that combined use of controlled release urea and normal urea to higher crop yields might attribute to increasing water extraction by optimizing in-season maize root morphology and distribution in the rainfed farmland of the Loess Plateau.
Highlights
Maize grain production must increase by 1.3% per year until 2025 to meet the demands of the increasing global human population, as it is expected to increase by two to three billion by 2050 [1].The application of nitrogen (N) fertilizer is one of the main methods to improve crop production [2].the excessive use of N fertilizer has no positive effect on yield [2] and causes a large amount of undesirable nitrate residual pollution, air pollution with emissions of N2 O and NH3, food security issues, and threats to land health [3,4,5]
Studies have shown that reducing the time of organic N is in soil solution before crop absorption can reduce the risk of N loss and increase N use efficiency (NUE) which is defined as the ratio of grain yield and the amount of N applied [6]
The root length density (RLD) in the three treatments declined with increasing soil depth and the root system was mainly distributed in the 0–40-cm soil layer (Figure 3)
Summary
Maize grain production must increase by 1.3% per year until 2025 to meet the demands of the increasing global human population, as it is expected to increase by two to three billion by 2050 [1].The application of nitrogen (N) fertilizer is one of the main methods to improve crop production [2].the excessive use of N fertilizer has no positive effect on yield [2] and causes a large amount of undesirable nitrate residual pollution, air pollution with emissions of N2 O and NH3 , food security issues, and threats to land health [3,4,5]. Maize grain production must increase by 1.3% per year until 2025 to meet the demands of the increasing global human population, as it is expected to increase by two to three billion by 2050 [1]. The application of nitrogen (N) fertilizer is one of the main methods to improve crop production [2]. Studies have shown that reducing the time of organic N is in soil solution before crop absorption can reduce the risk of N loss and increase N use efficiency (NUE) which is defined as the ratio of grain yield and the amount of N applied [6].
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