Water stress and appropriate N management achieves profitable yields and less N loss on sandy soils

Abstract

Attention is growing on the use of excessive nitrogen (N) and water in agricultural systems in Northwestern China because of lower water and N use efficiency. The soil NO₃⁻ dynamics and yield for cotton (Gossypium hirsutum L.) under the combined effects of drought and N additions, however, remain unclear. We investigated the effects of drought stress (367, 618, and 917 mm yr⁻¹) and N application levels (0, 150, 225, and 300 kg N ha⁻¹) on soil nitrate nitrogen (NO₃⁻) and yield in two years. Compared with optimum irrigation (917 mm), drought stress (618 and 367 mm yr⁻¹) significantly increased residual NO₃⁻ and decreased N loss. The 300 and 225 kg N ha⁻¹ treatment significantly increased NO₃⁻ content in most soil layers up to 200 cm depth, but N loss was also at a maximum with 300 kg N ha⁻¹. Applying 225 kg N ha⁻¹ with moderate drought stress (618 mm yr⁻¹) resulted in the highest cotton yields (2952 kg ha⁻¹⁾ and plant N uptake (148.7 kg ha⁻¹). Compared with the treatment of 150 kg N ha⁻¹ application with moderate drought stress (618 mm yr⁻¹), N agronomic use efficiency under the combination treatment of 225 kg N ha⁻¹ with moderate drought stress (618 mm yr⁻¹) had some decrease, but the difference was not significant. These results showed that reducing the N application rate to 225 kg N ha⁻¹ with moderate drought stress could be an optimum management practice for achieving high-yield, high-N use efficiency and could reduce soil N losses.

Keywords:

• Cotton
• irrigation
• nitrogen loss
• nitrogen use efficiency
• yield

Acknowledgments

We thank Linze Inland River Basin Research Station, Chinese Academy of Sciences, for providing the experiment site. We are grateful to the editor and two reviewers for their valuable comments, which substantially improved the manuscript. We thank LetPub (www.letpub.com) for its linguistic assistance during the preparation of this manuscript.

Additional information

Funding

This work was financially supported by the Scientific research startup funds for openly-recruited doctors [GAU-KYQD-2018-07], the National Natural Sciences Foundation of China [31960245] and the Discipline construction fund project of Gansu Agricultural University [GAU-XKJS-2018-104, GAU-XKJS-2018-108].