Water Availability Regulates Maize Reliance on Soil Versus Fertilizer Nitrogen in a Semiarid Environment

Authors

• Dwarika Bhattarai, South Dakota State UniversityFollow
• Janet Moriles Miller, South Dakota State UniversityFollow
• Sharon A. Clay, South Dakota State UniversityFollow
• David E. Clay, South Dakota State UniversityFollow

Document Type

Article

Publication Date

7-28-2026

Abstract

In semiarid environments, early-season water deficits create uncertainty in how much and when N fertilizer should be applied. To minimize indecision, a better understanding of the interrelationships among water availability, N rate, plant N sources, and yields is needed. This study investigated how soil water availability influenced maize (Zea mays L.) yields and utilization of soil- and fertilizer-derived N in semiarid environments in 2020 and 2021. The replicated trials were conducted at 12 sites and determined the impact of water availability and N rate on the sources of N within the grain, and precipitation and N use efficiencies (PUE and NUE, where NUE stands for nitrogen use efficiency and PUE stands for precipitation use efficiency). Based on grain δ¹³C and δ¹⁵N values, the relationship between water stress and fertilizer-derived N was determined. At the three sites where maize was not responsive to N application, yields were limited by water availability, with an average yield of 5.7 Mg ha⁻¹. At the nine sites where maize responded to N application, (1) the average economic optimum N rate and yield were 137 kg N ha⁻¹ and 11.5 Mg ha⁻¹, respectively; (2) yield was highly correlated to plant available water (PAW) at planting + cumulative precipitation at tasseling (CP_VT, r = 0.74, p <  0.05, where CP_VT stands for cumulative precipitation at tasseling stage); and (3) soil-derived N was positively correlated to PAW + CP_VT (r = 0.52, p <  0.01). The study also showed that increasing the N rate from 0 to 135 kg N ha⁻¹ increased PUE by 39.1%, while increasing the N rate from 45 to 135 kg N ha⁻¹ increased NUE by 13.4%.

Publication Title

Agronomy Journal

Volume

118

Issue

4

First Page

e70496

DOI of Published Version

10.1002/agj2.70496

Rights

Copyright © 2026 The Authors

Recommended Citation

Bhattarai, D., Moriles-Miller, J., Clay, S. A., & Clay, D. E. (2026). Water availability regulates maize reliance on soil versus fertilizer nitrogen in a semiarid environment. Agronomy Journal, 118, e70496. https://doi.org/10.1002/agj2.70496

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.