Coupled effects of rainfall-induced soil moisture and nitrogen placement depth on maize productivity and resource utilization in the Loess Plateau

Context and objectives

While deep nitrogen fertilization represents a well-established agronomic practice for enhancing yield stability by synchronizing nutrient availability with crop demand, the interactive effects of precipitation patterns and fertilization depth on crop performance and resource use efficiency remain poorly quantified, particularly in precipitation-sensitive dryland agroecosystems. Therefore, understanding how rainfall-driven soil moisture dynamics interact with the spatial distribution of soil nutrients to influence crop yield and resource use efficiency is critically important for improving the sustainability and productivity of dryland agricultural systems.

Methods

A field experiment was conducted from 2019 to 2022 to evaluate the effects of various nitrogen fertilizer placement depths [5 cm (D5), 15 cm (D15), 25 cm (D25), 35 cm (D35)] and different yearly rainfall patterns on the yield, crop water productivity and nitrogen use efficiency (i.e., WP and NUE), and net economic benefits (NEB) in dryland maize.

Results

Compared to long-term precipitation trends, crops received significantly higher amounts of precipitation during 2019 and 2020 growing seasons, but experienced a markedly drier growing season in 2022. Our results indicated that total seasonal precipitation and fertilizer placement depth had significant (P < 0.05) effects on grain yield, WP, NUE and NEB. In the wetter seasons (i.e., 2019 and 2020), the highest grain yield, WP, NUE and NEB were observed under D25, exceeding D5 by 13.83 %, 11.89 %, 38.37 % and 13.71 %, respectively. In the drier season (i.e., 2022), the best performances in grain yield, WP, NUE and NEB were achieved under D35, which were 26.12 %, 16.58 %, 51.58 % and 25.53 % higher than those under D5, respectively.

Conclusions

Our findings reveal a clear relationship between optimal fertilization depth and rainfall conditions. Specifically, a nitrogen application depth of 35 cm during drier growing seasons significantly improves maize yield, resource use efficiency, and economic returns. In contrast, a 25 cm placement is more effective in wetter years, optimizing productivity while minimizing the risk of nutrient leaching. This precipitation-responsive fertilization strategy represents a promising climate-adaptive practice, with the potential to improve both productivity and economic sustainability in semiarid maize cropping systems.